Nissim Silanikove

Abstract: The aim of this work was to study the effects of mastitis induced by intramammary lipopolysaccharide challenge on milk oxidative stability, as well as to understand the underlying biochemical processes that cause such changes. Lipopolysaccharide challenge was associated with nitric oxide burst from surrounding mammary epithelial cells and consequently provoked nitrosative stress that was induced by formation of NO2� from nitrite by lactoperoxidase. This response was associated with ~3 fold increased formation of hazardous compounds: nitrotyrosines, carbonyls and lipid peroxides. We sustained the involvement of xanthine oxidase as a major source of hydrogen peroxide. In consistent with previous findings, catalase has been shown to have a major role in modulating the nitrosative stress by oxidizing nitrite, to nitrate. The current hygienic quality criteria cannot detect mixing of low-quality milk, such as milk with high somatic cells and nitrite with high-quality milk. Thus, developing of improved quality control methodology may be found important for the production of high quality milk.

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Abstract: The effects of mammary gland bacterial infection and stage of lactation on leukocyte infiltration into the mammary gland were compared among cows, goats and sheep. Animals were at two stages of lactation: mid or late. In mid-lactation animals, bacterial-free glands and coagulase negative staphylococcus-infected glands were compared. In late lactation only uninfected glands were studied. Of mid-lactation bacteria-free animals, goats had the highest number of leukocytes and % polymorphonuclears, whereas sheep had the lowest and leukocytes number in cows were intermediate between sheep and goats. Based on %PMN, two cell clusters were found in sheep, which overlapped with the parallel cell clusters of cows and goats, but with a slightly higher number of leukocytes in each cell cluster. At late lactation, goats had higher values for %PMN and leukocyte numbers in comparison to cows, which had a similar cellular profile to sheep. The cellular immune response to CNS infection was similar for the three animal species, although the number of cells was different, while the basal cell level at mid-lactation and especially at the end of lactation was species specific.

Abstract: Background: A 3-yr study examined whether prepartum treatment with casein hydrolyzate in combination with antibiotic, as routinely used in Israel for dry cow therapy, improved bacterial cure and increased milk yield in subsequent lactations in comparison with treatment with antibiotic alone. The vast majority of bacterial isolates in samples collected prior to drying-off comprised coagulase-negative staphylococci, mostly as Staph. chromogenes. Results: Bacterial cure associated with the combined treatment was 73.8% in cows, significantly higher than the 51.7% cure recorded when cows were treated only with antibiotic. During the study, the annual milk yield of non-casein hydrolyzate treated and treated control cows increased at ~2% per year, which is consistent with the national annual increase attributed to genetic selection. In cows treated with casein hydrolyzate the increase was 9% (above the 2% expected) in the first lactation after the treatment, and 6.3% (above the 4% expected for 2 years) in the second lactation after treatment. These increases were significantly higher than those in the controls and those expected through genetic improvement. Conclusions: Treatment with casein hydrolyzate at dry-off was shown to be a viable mean to eliminate existing environmental bacterial infection, and to improve milk yield in the next lactation.

Abstract: A fluorometric-coupled reaction for the accurate and rapid determination malate, citrate, pyruvate and oxaloacetate is presented. The method was found useful for an accurate and rapid determination of these metabolites in low volumes of milk, yogurt, apple and lemon juice and wines without considerable pretreatment. In particular, this method was found valuable in characterizing the outcome of maloactic acid fermentation (MLF) in wine and outlined for the first time fundamental differences in MLF between red and white wines. Thus, this method has merit in analyzing these substances in heterogeneous, opaque and colorful foods.

Abstract: Milk clotting quality is highly affected by casein hydrolysis processes, which occur in the udder. Previously, we have shown that casein degradation products, Fractions C and E, impede milk clotting parameters. Fraction C is of particular interest since it is exclusively Streptococcus dysgalactiae-associated, both in bacteria-infected glands and upon ex-vivo inoculation of uninfected milk with the bacterium. Its effect on the clotting time and clot firmness, when added to control milk, is significant. The present study attempts to further investigate CN hydrolysis by specific bacteria, as expressed by the size distribution of proteos peptone sub-fractions, elucidate the structural properties of Strep. dysgalactiae FC and understand its role as an effector of milk clotting. MS, MS/MS and Edman degradation analyses suggested that this 14 kDa fraction comprises mainly the C-terminal fragment of �-CN. The nature of the enzyme which is responsible for its formation is yet obscure but it is definitely a bacterial enzyme since Fraction C preparations obtained from infected glands as well as from ex-vivo Streptococcus dysgalactiae inoculations were found identical. A model explaining a putative mechanism for impedance of milk clotting parameters upon formation of Fraction C is presented.

Abstract: Support of milk production in modern dairy cows demands large proportion of its own metabolic resources, such as glucose, which might be required under stressful situations. The aim of the experiment was to test the hypothesis that acute immune stress shifts oxidative metabolism to glycolysis. Two mammary quarters in 6 Holstein cows were infused with lipopolysaccharide (LPS), while the two counter quarters served as control to the treatment. An additional set of 6 cows were infused with saline and served as running control. LPS challenge induced dramatic transient increase of 75 folds in milk lactate and 11 folds in milk malate (markers of glycolysis) concentration of 75 at 24 h post treatment. No significant changes in lactate and malate concentration were recorded in control quarters and control animals, indicating that the effect of LPS was restricted to the treated gland. LPS challenge induced a dramatic transient decrease in milk yield, lactose and citrate (a marker of mitochondrial metabolism) secretion at 24 h post- treatment. The kinetics was inversely proportional to those of lactate and malate concentrations. Thus, our data suggest that LPS challenge induces acute conversion of the epithelial cells metabolism from principally mitochondrial-oxidative to principally cytosolic (glycolysis), which allowed the diversion of metabolic resources normally used to synthesize milk to support the immune system. In vitro bacterial growth test showed that concentrations of lactate and malate and lactose equivalent to those found in the in vivo experiment delayed and reduced the growth of pathogenic Escherichia coli strain, suggesting that they play a role in diminution of the bacterial multiplication in the mammary gland.

Abstract: Previously, we have hypothesized that the dissociation of the dam-offspring interrelationships (i.e., induction of mammary gland involution) is preceded by metabolic and immunological adaptive response. Indeed, in the present study we have shown that genetically high-producing cows producing low amount of milk before the expected period of involution show signs of auto-defense metabolic mechanism that was associated with an orderly involution process and effective antimicrobial immune response. On the other hand, in non-adapted cows that yielded copious amount of milk before expected involution this process was associated with acute response (neutrophilia and lymphopaenia) that resembled a wood-healing response and was much less effective in terms of antimicrobial clearing capacity.

Abstract: Effects of glandular bacterial infection and stage of lactation on milk quality were compared among cows, goats and sheep. These parameters affected milk quality in all three species: sheep were most affected by bacterial infection and goats by stage (particularly end) of lactation. The study highlighted the effectiveness of lactose level as a predictor of milk quality; in all three species, the correlation between lactose level and curd firmness (CF) was higher than those between casein as a percentage of total protein and CF, or between somatic cell count and CF. In all three species, lactose concentrations � 4% were associated with non-clotting milk. A model that describes the simultaneous and close association between reductions in lactose concentration and milk yield, on the one hand, and reductions in lactose concentration and milk quality on the other hand, is presented.

Abstract: Goat milk production is a dynamic and growing industry that is fundamental to the wellbeing of hundred of millions of people worldwide and is an important part of the economy in many countries. The aim of the present review is to provide an integrated and critical analysis of the major aspects in this field to highlight unexploited nutritional potential of goat milk and the need for improvements, particularly in food-safety. First, it should be kept in mind that goat milk like cow milk delivers many nutrients with relatively low energy content, and is relevant to the health of consumers throughout the life cycle. In addition, our review presents data suggesting that goat milk possesses many advantages over cow's milk, for use as a nutritional source for infants and children and as a medicinal food. Furthermore, we suggest that goats, by consuming large amounts of natural browsing plants all year around, is a potentially overlooked "treasure trove", with respect to health promoting components. Our survey suggests that total bacterial count that is currently used as the major quality measure to prevent pathogen-related food toxiciosis in Europe and the USA is not sufficiently effective. We propose the inclusion of somatic cells count as a routine criterion to qualify the hygienic status of goat milk, and discuss the physiological and biochemical basis for this. Finally, we present a novel mechanism controlling milk secretion, and demonstrate the use of this knowledge in making decisions for two major managemental tasks that farmers face: i) Milking frequency that dictates to large extent the milk yield and workload in the farm, and ii) Helping to deal with subclinical mastitis, which is the single major cause for economical losses in dairy farms worldwide.

Abstract: A fluorometric-coupled reaction for the accurate and rapid determination D and Llactate and lactose, galactose in foods is presented. The method was found useful for an accurate determination of these metabolites in heterogeneous, opaque and colorful foods without pretreatments. Example for the determination of lactose, galactose, D- and Llactate in milk, and yogurts and D- and L-lactate in milk, wine and beer is provided. Unexpectedly, we found that the composition of some commercial bio-yogurts produced in Israel is not consistent with the classical definition of yogurts. Thus, this method offers rapid and accurate methodology, which should be particularly valuable in food quality control.

Abstract: Galls are abnormal plant growth induced by various parasitic organisms, mainly insects. They serve as �incubators� for the developing insects in which they gain nutrition and protection from both abiotic factors and natural enemies. Galls are typically armed with high levels of defensive secondary metabolites. Conspicuousness by color, size and shape is a common gall trait. Many galls are colorful (red, yellow etc.) and therefore can be clearly distinguished from the surrounding host plant organs. Here we outlined a new hypothesis, suggesting that chemically protected galls which are also conspicuous are aposematic. We discuss predictions, alternative hypotheses and experimental tests of this hypothesis.

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Abstract: The enzyme catalase is well-known to catalyze the disintegration of hydrogen peroxide to water and oxygen; however, this study shows that its main function in bovine milk is oxidation of nitrite to nitrate. This process depends on hydrogen peroxide, of which the main source appears to be hydrogen peroxide formation that is coupled to the conversion of purines�xanthine in the present study�to uric acid by milk xanthine oxidase. However, additional secondary sources of hydrogen peroxide appear to be important during the relatively long storage of milk in the gland cistern. This paper demonstrates that the oxidation of nitrite to nitrate is necessary to prevent accumulation of free radicals and oxidative products during storage of milk in the gland and during the unavoidable delay between milking and pasteurization in dairy plants. Recommendations for minimizing the deterioration in milk quality during commercial storage are presented.

Abstract: The aim of the present study was to determine the effect of polyethylene glycol (PEG) supplementation on grazing behaviour of beef cattle and on utilization of the woody components of a Mediterranean shrubland. Two experiments were conducted on two different sites in Northern Israel, Ramat Hanadiv (RH) and Hatal. On each site, the study area was divided into two paddocks, in one cattle were supplemented with 50 g PEG day� 1 per cow, while the other served as a control, with no PEG supplementation. In RH site the cows had free access to Prolix and in Hatal to poultry litter, both serving as a nitrogen supplement during the experiment. In the RH site, the consumption of Pistacia lentiscus, a shrub whose leaves contain high concentration of tannins, was found higher (P = 0.001) in the PEG group diet than in the control group. In Hatal site PEG increased foraging time by 18%, daily foraging distance by 15% and reduced the use of supplementary feed (poultry litter) by 20%. However, PEG did not affect the average cow body weight or water consumption on either site. It is concluded that PEG influences grazing behaviour of beef cattle on shrubby rangeland and increases the use of woody species with high tannin concentrations.

Abstract: Background: The objective of this study was to determine if acute heat stress (HS) decreases milk secretion by activating the milk-borne negative feedback system, as an emergency physiological response to prevent a life-threatening situation. To induce HS, summer acclimatized dairy cows were exposed to full sun under mid-summer Mediterranean conditions, with and without conventional cooling procedures. Results: Exposure to HS induced a rapid and acute (within 24 h) reduction in milk yield in proportion to the heat load. This decrease was moderated by cooler night-time ambient temperature. The reduction in milk yield was associated with corresponding responses in plasminogen activator/plasminogen-plasmin activities, and with increased activity (concentration) of the (1-28) N-terminal fragment peptide that is released by plasmin from β-casein (β-CN (1-28)). These metabolites constitute the regulatory negative feedback system. Previously, it has been shown that β-CN (1-28) down-regulated milk secretion by blocking potassium channels on the apical aspects of the mammary epithelial cells. Conclusions: Here we demonstrate that the potassium channels in mammary tissue became more susceptible to β-CN (1-28) activity under HS. Thus, the present study highlighted two previously unreported features of this regulatory system: (i) that it modulates rapidly in response to stressor impact variations; and (ii) that the regulations of the mammary epithelial potassium channel sensitivity to the inhibitory effect of β-CN (1-28) is part of the regulatory system.

Abstract: The levels of immunoglobulin type G (IgG) and ganglioside type M1 (GM1) in the colostrum of cows and heifers were analyzed in order to examine their utility in predicting acquisition of intramammary infection (IMI) during the first weeks postpartum .In general, high levels of IgG and GM1 in cows were associated with lower new incidence of IMI, and linear discriminate analysis based on these two variables yielded 70% successful classification, i.e., into cows that did or did not acquire new IMI This analysis was less successful in heifers because a high proportion of them joined the herd when already infected with bacteria in their udders. It is suggested that application of a wider range of measures that reflect the immune status would enable most cows prone to new IMI to be identified. INTERPRETIVE SUMMARY We show that high levels of immunoglobulin type G and ganglioside type M1 were associated with lower new incidence of intramammary infection (IMI). Discriminate analysis based on these two variables yielded 70% successful classification into cows that did or did not acquire new IMI. This analysis was less successful in heifers because a high proportion of them joined the herd when already infected with bacteria in their udders. This study raises the hope that examining a broader selection of indicators of immunity would enable reliable identification of most of the cows in a given herd that are prone to mastitis in early lactation.

Abstract: There are two main sources of lipoprotein membranes in milk: the relatively well-defined milk fat globule membrane (MFGM) that covers the milk fat globules, and the much less attended lipoprotein source, in the form of vesicles floating in the milk serum. We challenge the common view that the milk serum lipoprotein membrane (MSLM) is secondly derived from the MFGM and present a different view suggesting that it represents Golgi-derived vesicles that are released intact to milk. The potential role of enzymes attached to the MSLM and MFGM is considered in detail for select ubiquitously expressed enzymes.

Abstract: Abstract: Refrigerated storage of good-quality milk from a single cow resulted in moderate deterioration of its quality, low level of bacterial growth (standard plate and psychrotroph counts), and low small losses of curd yield. When milk was collected from farm bulk milk tanks and from dairy silos, its quality deteriorated faster than that of single-cow milk, resulting in high bacteria counts and high loss of curd yield, most of which was already apparent for the farm bulk milk tank. Statistical analyses did not reveal any significant interaction between bacterial growth, milk composition, somatic cell count, and curd yield loss, indicating that other mechanisms such as enzymatic activity might be responsible. From the comparison between the high-quality milk from an uninfected cow's udder and the commingled milk on the farm and in the dairy silos, it appears that introduction of milk coming from infected udders might cause curd yield loss such as that noted in the present study. (Document Type: Article

Abstract: Milk from glands infected with Streptococcus dysgalactiae was almost identical in gross composition to milk from uninfected glands. However, yogurt and cheese made from commingled milk from the infected quarters exhibited inferior texture compared to yogurt and cheese made from uninfected ones. Proteose peptone was size-fractionated by gel filtration and the various fractions of milk from the infected glands were added to uninfected milk. This study demonstrated for the first time that addition of certain fractions to milk from uninfected glands resulted in altered milk coagulation properties. It is hypothesized that the infecting bacteria influence the immune system of the udder, which then impairs the qualities of the milk from infected quarters that is conventionally used for manufacturing of dairy products.

Abstract: Abstract: Equations for predicting milk and curd loss due to intramammary infection in sheep and goat herds were derived. The empirical equations were derived from previously published studies conducted by this team with Assaf sheep and crossbreeds of goats in Israel. From these equations, it appears that infection of 25, 50 and 75% of the udders in a given herd was associated with loss of 4.1-12.2.5% milk in sheep and 0.8-2.3% in goats; whereas curd loss was 5.2-15.5% in sheep and 3.3-9.8.9% in goats. Based on percent of udder infection and projected SCC, the following categories are suggested for classification of sheep and goat milk: i. High-quality milk <800,000 SCC/mL, associated with infection of similar to 25%; ii. Medium quality milk <1,500,000 SCC/mL, associated with infection rate between 25 and 50%; iii. Low-quality milk >1,500,000 SCC/mL, associated with infection rate above 50%; iv. Milk containing >3,500,000 SCC/mL should not be accepted for human consumption.

Abstract: Abstract: A cow that was incorrectly identified as pregnant was "dried-up" conventionally about 60 days before her expected date of parturition. It was noted that the cow was not pregnant at all, although her udder was fully induced into involution. Histological examination of the mammary gland revealed that the milk glands underwent stage II involution and the udder assumed the appearance of that of a virgin cow.

Abstract: Although there has been little study of the origin of intramammary infection (IMI) in goats, a common view is that most bacterial infection in goats occurs during milking. In the present study, the dynamics of occurrence of udder infection during and between lactations in three Anglo-Nubian goat farms in Israel was monitored. Coagulase-negative staphylococci were the predominant bacteria in the IMIs. We found that about 15% of the yearling does were already infected with bacteria when they joined the flock, whereas about 8% of the goats that dried-off returned with new IMIs. Moreover, virtually none of the goats acquired infection during lactation. Thus, our study showed that the aetiology of IMI in goats is very similar to that in dairy cows. A preventive treatment during the dry period should, therefore, be considered as an effective means of reducing the current rate of bacterial infections in goats.

Abstract: The aim of this study was to evaluate the distribution of xanthine oxidoreductase (XOR) and its two forms, xanthine oxidase (XO) and xanthine dehydrogenase (XD), in milk fractions. XOR associated with milk phospholipid membranes was found to be distributed among an intra-membranous pool in which it takes the form of a mixture of XO and XD, with a clear predominance of XD, and a free pool of XO, of which 33% is found in the outer surface of milk fat globule membrane, 20.5% in the outer surface of whey membrane particles, and the remaining 46.7% in apparent solution. The inner-membrane XOR may play a nonenzymatic role in fat secretion, whereas extra-membranous XO is freely available for a role in the innate gland immune system and may affect milk quality.

Abstract: The effectiveness of casein hydrolyzate as mean to improve the welfare of cows induced into involution was tested in high yielding cows induced into dry-off by abrupt cessation of milking. Treatment with casein hydrolysate prevented build up of udder pressure in cows induced into dry off and was clearly associated with signs (lying behavior and step numbers) that they were calmer and more comfortable than cows induced into dry off by the conventional means. We conclude that treatment with casein hydrolyzate is a viable treatment tool that can prevent the suffering associated with drying-off of high-yielding modern dairy cows.

Abstract: The aims of this study were to test the hypothesis that the substrates of xanthine oxidase (XO), xanthine and hypoxanthine, are consumed while the milk is stored in the gland between milkings, and to explore how XO activity responds to bacteria commonly associated with subclinical infections in the mammary gland. Freshly secreted milk was obtained following complete evacuation of the gland and induction of milk ejection with oxytocin. In bacteria-free fresh milk xanthine and hypoxanthine were converted to uric acid within 30 min (T1/2 approximately 10 min), which in turn provides electrons for formation of hydrogen peroxide and endows the alveolar lumen with passive protection against invading bacteria. On the other hand, the longer residence time of milk in the cistern compartment was not associated with oxidative stress as a result of XO idleness caused by exhaustion of its physiological fuels. The specific response of XO to bacteria species and the resulting bacteria-dependent nitrosative stress further demonstrates that it is part of the gland immune system.

Abstract: Over 60 indigenous enzymes have been identified so far in the milk of various mammalian species. The vast majority of research in this area has focused on their use as indicators of processing (mainly pasteurization), contribution to dairy product quality and investigating the factors that affect their level in milk. The aim of this article is to provide an overview of data accumulated during the last 5 years, mostly for bovine and human milk, which shows that milk indigenous enzymes play a key role in regulating lactogenesis, e.g., inducing active involution, and that they are essential components of antioxidation and the innate immune system of milk.

Abstract: There are contradicting data in the literature regarding condensed tannins content in carobs. In this study, urea (0.5 g/ml) under reflux conditions increased dramatically the yield of condensed tannins to 17% of dry matter, as compared to 3.5% in acidic methanol extraction. This shows that carob pods are rich source of nonextractable condensed tannins. The effect of PEG in diet rich in carob pods on voluntary feed intake, digestibility and growth in weaning kids was studied during 15 days of balance trials in 24 kids distributed into three dietary treatments. The corn grain and wheat bran components in the control diet (diet 1) were replaced by carob in treatments 2 and 3; treatment 3 was supplemented by 3.3% of PEG of molecular weight-4000. Food intake, diet utilization and growth rate of weaning kids fed a diet containing 52% carob pods were decreased considerably in comparison to kids fed the control commercial diet. Supplementing the kids fed the carob-based diet with PEG increased feed intake, crude protein digestibility and growth to the rate obtained with the control diet. The nutritional experiment highlights the following aspects relevant to all mammals consuming carob pods rich diets: (i) tannins increased the variability in feed intake between days, (ii) hypocholesterolemic effect of carob pods is related to lipid binding capacity of nonextractable condensed tannins in the digestive tract, (iii) supplementing high level of carob pods to animals with normal blood cholesterol level may induce hypocholesterolemia.

Abstract: The effects of separate infection with four major pathogens frequently associated with the occurrence of subclinical mastitis in cows (Staphylococcus aureus, S. chromogenes, Escherichia coli and Streptococcus dysgalactiae) on milk quality for cheese production were studied for quarters of the same animal. Infection increased somatic cell count (SCC), modified leucocyte distribution, decreased lactose concentration and increased proteolysis of casein. Regardless of bacteria type, the plasmin activity in milk from the infected glands increased 2 fold compared with uninfected quarters. These changes were associated with increased rennet clotting time and decreased curd firmness for milk from infected glands, indicating that milk quality for cheese production was negatively affected by infection. Although the general pattern of bacterial invasion was similar, each type of bacteria elicited the above-described responses in a specific manner. SCC, commonly used by the dairy industry as a measure of milk hygienic quality, provided the poorest prediction of milk quality for cheese production in comparison to indices of proteolysis of casein.

Abstract: The current ruminant protein systems aim at synchronizing the provision of rumen degradable organic matter (RDOM) and degradable crude protein (RDCP) but no specific information on their optimal ratio for dairy sheep is available. We studied the effect of the ratio of RDOM to RDCP on milk yield and composition, during a summer lactation, in 34 confined Assaf sheep managed under farm condition. Individual feed intake was assessed by using PEG (MW 4000) as external marker of fecal output, and indigestible INDF as internal marker of digestibility. Four total mixed rations contained two levels of RDCP (108 and 117 g/kg DM) and two levels of RDOM (510 and 570 g/kg DM). This resulted in one diet featuring high (5.3), one diet featuring medium (4.8) ratio, and two diets featuring low (4.5) ratio of RDOM to RDCP. Individual DM intake, digestibility, and the daily yields of milk components were not affected by RDOM, RDCP or RDOM/RDCP. High RDOM/RDCP tended (P < 0.10) to be associated with higher milk yield, and lower (P < 0.05) CP content. The casein/CP ratio and urea-N in milk were lowest when both dietary RDCP and RDOM were low, whereas lactose was highest (P < 0.05) when both RDOM and RDCP concentrations were high. Our data suggest that RDOM and RDCP interact on milk composition in a way that is not fully encompassed by the RDOM/RDCP ratio and that the use of this ratio to formulate diets for pre-determined milk composition is not warranted.

Abstract: Albumin is a well-characterized product of the liver. In the present study, objectives were to determine if the albumin gene is also expressed in various nonhepatic tissues in the bovine; whether mammary gland epithelial cells synthesize albumin; and how its synthesis is affected by bovine mastitis. Albumin expression was monitored using reverse transcription-polymerase chain reaction. Tissues examined were: liver, mammary gland, tongue, intestine, lymph gland, testicle, ovary, and uterus. All tissues except the ovary expressed the albumin gene, albeit less so than the liver. The highest level of expression (other than liver) was found in the lymph nodes but expression was also found in the mammary gland. Incubation of mammary gland explants with the labeled amino acid L-[(35)S] methionine resulted in formation of labeled immunoprecipitable albumin, newly synthesized in the explant. Immunoprecipitable albumin in the medium verified that newly synthesized albumin was also secreted into the medium. This shows that the gland itself is a source of milk albumin. Albumin mRNA expression was approximately 4 times higher in mammary gland tissue from 6 mastitic cows compared with expression in mammary tissue from 6 healthy glands. Further, secretion of albumin was increased 3.5-fold from explants of mastitic mammary glands compared with secretion from explants of healthy mammary glands. Addition of lipopolysaccharide increased the synthesis and secretion of albumin in mammary gland cells in a dose-dependent manner. Exposure to lipopolysaccharide accelerated albumin synthesis in a time-dependent manner up to 48 h. These results lead us to suggest that the secretion of albumin by the mammary gland is part of the innate nonspecific defense system.

Abstract: The aims of this study were to test whether xanthine oxidase, lactoperoxidase, and NO are components of the innate immune system of mammary secretion during active involution in dairy cows, and whether the innate immune system is activated by casein hydrolysates. Our laboratory has shown recently that infusion of CNH into mammary glands induced involution and was associated with earlier increases in the concentrations of components of the innate immune system. Intact casein is inactive and served as control. Half of the glands of 8 Holstein cows scheduled for dry off (approximately 60 days before parturition) were injected for 3 days with a single dose of casein hydrolyzates and the contralateral glands with a single dose of intact casein with the same concentration. Involution elicited marked increases in xanthine oxidase and lactoperoxidase activities, and accumulation of urate and nitrate. NO and H(2)O(2) were constantly produced in the mammary gland secretion. Nitrite formed either by autooxidation of NO or by conversion of nitrate to nitrite by xanthine oxidase was converted into the powerful nitric dioxide radical by lactoperoxidase and H(2)O(2) that is derived from the metabolism of xanthine oxidase. Nitric dioxide is most likely responsible for the formation of nitrosothiols on thiol-bearing groups, which allows an extended NO presence in mammary secretion. Nitrite is effectively converted to nitrate, which accumulated in the range of approximately 25 microM -1 mM from the start of the experiment to the complete involution of glands. The mammary secretion in all glands was bactericidal and bacteriostatic during established involution, and this appeared sooner and more acutely in glands treated with casein hydrolyzates, within 8 to 24 h. It is concluded that xanthine oxidase, lactoperoxidase, and NO are components of the mammary innate immune system that form bactericidal and bacteriostatic activities in mammary secretions. The innate immune system play a major role in preventing intramammary infection during milk stasis and its activation may increase its effectiveness.

Abstract: The present study focused on gaining a better insight into how subclinical mastitis at the gland level in dairy sheep and goats affects milk yield and compositional changes in relation to curd yield. Animals chosen for the study had one udder half infected with identified coagulase-negative staphyloccocci (CNS) species and the contra-lateral gland was free of bacteria. Udder halves were tested for udder bacterial condition, California mastitis test, somatic cell count (SCC), milk yield, milk composition (fat, protein, lactose, casein (CN), and whey protein), curd yield (dY) and in ilk clotting time (Tc). Data were statistically analyzed with a nested block design. Curd yield from the infected halves was lower than that from the uninfected ones for both sheep and goats, although CN concentrations were almost equal in the two glands. The data suggest that knowledge of the gross CN content in the milk is insufficient for predicting dY, probably because of modifications in the CN micelles or in the various casein micelle components that are more detrimental to curd formation than they are to the CN concentration itself. The primary enzymatic coagulation is based on the action of rennin on K-casein, which thereafter exposes hydrophobic sites on the casein micelle, thus making it available for the secondary aggregation reaction. The complications in the coagulation process are also supported by the longer Tc of the milk from the infected glands. However, the effect of rennet on the caseins and thereafter the coagulation process may be impeded by only partial hydrolysis Of K-casein and more pronounced hydrolysis of the other caseins by enzymes such as PL and cathepsin.

Abstract: Nutritionists are interested in functional assays of tannins that do not require time-consuming and expensive extraction, such as the (14)C-labeled poly(ethylene glycol) (PEG)-binding (PEG-b) assay. This paper reports the application of near-infrared (NIR) spectroscopy to determine the percentage of PEG binding, in place of the (14)C-labeled PEG-b assay of tannin, in Mediterranean woodland vegetation. Calibration was done with 53 samples from 14 species and was validated on 25 samples from 10 species. PEG-b ranged between 1.4 and 20.7% in the samples. The calibration obtained by using the modified partial least-squares (MPLS) method, with all wavelengths in the 1100-2500 nm range combined, and the validation were reasonably linear (R (2) = 0.96 and 0.91, respectively). The accuracies, estimated from the standard errors of cross-validation and prediction, were +/-1.6 and +/-1.7% PEG-b, respectively. The NIRS-aided procedure proposed here can serve as an accurate, inexpensive, time-saving, and environment-friendly functional assay of tannin in Mediterranean browse.

Abstract: The study was aimed at identifying the pathogens causing subclinical udder infections in representative Israeli dairy goat herds and determining their effect on milk quality. Five hundred goats in ten flocks of various breeds and crossbreeds were surveyed. Of the 500 goats, 13.4% were in their first lactation, 36.4% were in their second lactation and 50.2% were in their third or higher lactation. Percentages of udder halves with subclinical intramammary infection in the flocks ranged from 35 to 71%. The effect of the bacteriological infection on somatic cells count (SCC) was significant (P<0.001). Various species of coagulase-negative staphylococci (CNS), mainly Staphylococcus caprae and Staphylococcus epidermidis, were the main pathogens in infected udder halves. Lactation number did not significantly influence either infection rate of udder halves or SCC, although the percentage of udder halves with no bacteriological findings was higher at the first lactation than at the third lactation. Milk composition (fat, protein and lactose) varied among flocks, with lower mean total protein in uninfected halves than in infected ones and higher lactose in uninfected than infected halves.

Abstract: The mechanism of the effects of subclinical mastitis (SM) at the glandular level in dairy goats on milk yield and its composition as expressed in curd yield (Yc) was studied. Twenty-five Israeli goats of various crossbreeds were chosen; one udder half was naturally infected with identified coagulase-negative staphylococci, and the contralateral gland was free of bacteria. The milk yield of the infected halves was significantly lower than that of the uninfected ones. Somatic cell count and N-acetyl-beta-D-glucosaminidase activity were significantly higher in the infected halves. The lactose concentration in the infected glands was significantly lower than that in the uninfected ones, casein concentrations did not differ, and the whey protein and albumin concentrations were significantly higher in the infected glands. Plasmin activity was significantly higher in the infected glands, whereas plasminogen activity was undetectable. Concentrations of Ca2+ did not differ, whereas Ca2+ activity was significantly lower in the infected glands. The proteose peptone concentration was 1.5 times as great in the infected glands as in the uninfected ones. The Yc was significantly lower in the infected halves, and clotting time was significantly longer. The mechanisms of the effects of SM on milk yield and Yc in goats and sheep are discussed and compared.

Abstract: The present report focuses on how the differences in the plasmin (PL) system between sheep and goats are reflected in their response to subclinical intramammary infection (IMI), particularly in respect to casein (CN) degradation and milk yield (MY). Plasmin is the major proteolytic enzyme in milk, where it is found mostly in its inactive zymogen - plasminogen (PLG), which is activated by plasmin activator (PA). Both plasmin activator (PA) and PL activities in goats in late lactation and goats with subclinical IMI are negatively correlated with MY and the coagulating properties of milk, suggesting that this system is important in goats as well. The higher CN content along with higher PL activity in sheep compared with goats resulted in higher CN degradation products that include factors that down-regulate milk secretion, which explains the more acute response in MY. Sheep are more vulnerable than goats to sub-clinical infections in terms of MY.

Abstract: The mechanism of the effects of glandular-level subclinical mastitis in dairy sheep on milk yield and on its composition as expressed in curd yield was studied. Thirty-six Israeli-Assaf dairy sheep with one udder half infected with identified coagulase-negative staphylococci and the contralateral gland free of bacteria were chosen. The milk yield of the infected halves was significantly lower than that of the uninfected ones (0.36 vs. 0.76 kg/milking). The somatic cell count and N-acetyl-beta-D-glucosaminidase activity were significantly higher in the infected halves than in the uninfected ones. The plasminogen activator and plasmin (PL) activities were significantly higher in the infected glands than in the uninfected ones, whereas plasminogen (PLG) activity and the ratio PLG:PL were significantly lower in the infected glands. Concentrations of Ca2+ did not differ, whereas Ca2+ activity was significantly lower and proteose peptone concentration was 2.4 times as high in the infected glands than in the uninfected ones. Curd yield was significantly lower in the infected glands than in the uninfected ones.

Abstract: Forty-eight Boer x Spanish doelings (4 mo of age, 20.9 + 2.35 kg) were used to test effects of polyethylene glycol (PEG) supplementation of grazed sericea lespedeza and early post-weaning nutritive plane and growth rate on subsequent performance with a concentrate-based diet fed in confinement. Treatments were: Barn, with goats kept in individual pens for the 24-wk trial and fed a 70% concentrate diet (17% CP, 69% TDN) free-choice, C, and PS, with two groups of eight doelings per group for each treatment. In the first 6 wk (Phase 1), C and PS groups grazed 0.4-ha lespedeza paddocks (two paddocks and groups per treatment) and were group-supplemented with 88 g/d per animal of concentrate without (C) or with (PS) an additional 25 g/d per animal of PEG. Because of limited rainfall in Phase 1 and the resultant low availability of growing forage, in Phase 2 (6 wk) treatments were changed in a manner thought to increase differences in BW and ADG between C and PS that developed in Phase 1. In Phase 2, C groups resided in two 1-ha paddocks dominated by crabgrass, whereas PS groups grazed two previously ungrazed 1-ha lespedeza paddocks and were supplemented with 1.5% BW of the Barn diet. In Phase 3, the final 12 wk, all doelings consumed ad libitum the 70% concentrate diet in confinement. Phase 1 ADG ranked (P < 0.05) Barn > PS > C (154, 95, and 47 g/d, respectively; SE 10.7). ADG in Phase 2 (70, 55, and 57 g/d; SE 9.3), Phase 3 (77, 82, and 72 g/d; SE 8.5), and the whole trial (94, 78, and 62 g/d for Barn, PS, and C, respectively; SE 8.2) were similar among treatments (P > 0.05). In conclusion, PEG may have potential to improve ADG by goat kids grazing tannin-containing sericea lespedeza, although testing over a longer period of time is needed. Differences in ADG in the early portion of the grazing period did not affect ADG later when a concentrate-based diet was fed, relative to continuous consumption of the concentrate-based diet.

Abstract: Milk stasis triggers local stimuli, which make the tight junctions leak and trigger involution. The aim of the study was to test the hypothesis that casein hydrolyzates compromise tight junction integrity and dry-off milk secretion in dairy cows. Six repeated doses of casein hydrolyzates after each milking during 3 d caused drastic changes in mammary secretion and composition, which were associated with irreversible cessation of milk secretion. No such changes were recorded in the control glands that had been treated with nonhydrolyzed casein. Treatment with casein hydrolyzates disturbed tight junction integrity within 8 h (as indicated by changes in Na+ and K+ concentrations), reduced the concentrations of lactose precipitously, activated the plasmin activator-plasminogen-plasmin system, and induced the secretion of immunoglobulin type G and lactoferrin. At the end of the 3-d treatments, we stopped milking the experimental and control glands. Milk composition 19 d later was similar in the experimental and control glands and was consistent with the composition expected in fully involuted glands. We conclude that casein hydrolyzates are among the milk-borne factors that cause the disruption of tight junction integrity and induce involution in cows. The process induced by casein hydrolyzate was more rapid and synchronized than the involution induced at drying-off.

Abstract:

Abstract: Our objective was to provide a review of factors influencing heat stress in lactating dairy cows and how it affects milk production. In warmer parts of the world, during summer months in the United States, and in other temperate regions, reduced milk production resulting from heat stress counteracts tremendous genetic progress achieved in increasing milk production. Genetic progress in milk production is closely related to increased feed intake. High feed intake results in raised metabolic heat increment. High metabolic heat increment requires effective thermoregulatory mechanisms to maintain body temperature in a thermoneutral zone and in physiological homeostasis. Cows can succumb to hyperthermia if they fail to maintain thermoneutrality. Accurate measurement of when cows enter heat stress is complicated because the responses to heat stress affect not only the energy balance, but also water, sodium, potassium and chlorine metabolism. Water, sodium, potassium and chlorine are important constituents of sweat, and sweating is a major, if not the most important, thermoregulatory mechanism used to dissipate excess body heat. Due to high metabolic heat increment, and especially in the warmer months, high-producing dairy cows may enter heat stress much earlier than their lower-producing counterparts and than currently thought, or extra heat has been accommodated by physiological adaptations. Should this be the case, then strategies to reduce heat stress must be developed to enable cows to express their full genetic potential. The thermoneutral zone, heat production and heat gain, heat dissipation mechanisms, and how the lactating cow responds to heat stress are discussed.

Abstract: High concentrations of condensed tannins in browse impair brush clearing by goats. We studied the effect of polyethylene glycol (PEG, MW 4000), a polymer that binds condensed tannins, on the feeding behavior of Damascus goats (Capra hircas) on a range dominated by tannin-rich lentisk (Pistacia lentiscus L.). This was done with or without a nutritious alternative to browse (alfalfa hay) available at pasture. In phase 1, no hay was-provided to goats; in phase 2, hay was distributed daily in the field. In both phases, 6 goats had free access to PEG while at pasture, while 6 goats that grazed separately on another paddock did not. All goats received each night an allowance of concentrate (400 g day(-1) of 40% ground corn grain, 40% ground barley, 17% soybean meal and 3% of a mineral-vitamin premix, and contained as fed 16% crude protein (CP) and 2.66 Mcal kg(-1) of Metabolizable Energy). The 2 groups of goats alternated daily between paddocks. Goats supplemented with PEG spent more time browsing lentisk than goats in the control group (73 and 41%, respectively, P < 0.0001). Goats in the control group spent more time foraging on dry grasses than their PEG-fed counterparts (28 and 12%, respectively, P < 0.0001). Goats from the PEG group gained body weight at a higher rate than controls. The daily intake of PEG was 450 g, with an intake rate of 1.2 g sec(-1). Supplemental alfalfa hay substituted partly for dry grasses in goats' diets, but did not modify the percent of time goats in either treatment spent browsing lentisk. Our data suggest that PEG has the potential to increase intake of tannin-rich species, even where alternative fodder of better nutritional quality is present. However, self-feeding of PEG may not be the best way to provide PEG because goats may ingest more PEG than needed to annul the aversive effects of tannins on food intake.

Abstract: Abstract Replacement of NAD by thio-NAD and measurement at 405 rather than 340 nm can be used in the determination of lactose and galactose. These modifications allow microplate-readers rather than UV spectrophotometers to be used in the assays.

Abstract: Mammary involution is triggered by local stimuli, but the precise mechanism has not been defined. Milk stasis accumulate local signals, which makes the tight junctions (TJ) leaky. The aim of the study was to check the hypothesis that casein hydrolyzates (CNH) compromise TJ integrity and dry up milk secretion. A single dose of CNH transiently (12 to 24 h) compromised TJ integrity in the treatedudder. This was associated by a transient (12 to 96 h) decline in milk secretion. No such changes were recorded in the contralateral gland that served as a control. Four repeated doses of CNH after each milking caused drastic changes in mammary secretion and composition, which were associated with irreversible cessation of milk secretion within 96 h. No such changes were recorded in goats treated with de-phosphorylated casein (control). We conclude that CNH are the milk-borne factors that cause the disruption of TJ integrity and induction of involution, and that the serine-Ps in the CNHs are essential for the excretion of biological activity.

Abstract: Supplemental polyethylene glycol (PEG) increases intake of foods high in tannins, but it is not known if PEG affects preference when herbivores forage on a variety of foods that differ in concentrations of macronutrients and tannins, We investigated how macronutrients, tannins, and PEG affected preferences of goats (Caprus hircus) for current season's and older growth twigs from the shrub blackbrush (Coleogyne ramosissima Torr.), In blackbrush, current season's twigs are higher than older twigs in macronutrients, but goats prefer older twigs because high levels of tannins in current season's twigs decrease preference. We conducted a pen trial and a paddock trial. During the 7-day pen trial, goats were offered current season's twigs and older twigs throughout the day. Eight goats were supplemented with 20 g PEG mixed with 100 g ground alfalfa (Medicago sativa L.) pellets, and 8 goats were supplemented with 100 g ground alfalfa pellets. Goats supplemented with PEG ate more current season's twigs than goats that did not receive PEG (P = 0.04). During the 17-day paddock trial, 10 goats were supplemented with 50 g PEG mixed with ground alfalfa/barley (Hordeum vulgare L.), and 10 goats were supplemented with ground alfalfa/barley, Goats supplemented with PEG preferred current season's to older twigs, whereas PEG-unsupplemented goats preferred older to current season's twigs (P = 0.0001). Goats had equal preference for juniper (Juniperus osteosperma Torr.) trees (P = 0.243), Collectively, our findings show that supplemental PEG can change food preferences.

Abstract: We examined the effect of calving month (CM) on the production of milk and milk protein by Israeli Holstein dairy cows located in the main climatic zone of Israel during their third and fourth lactations, and found it to be significant. Cows that calved in December produced the highest milk and milk protein yields, and those that calved in June produced the lowest, 92.8% of the maximum. The combined effect of the environmental average temperature and day length accounted for 0.96 of the variability in average milk production during lactation and 0.93 of that in average protein production during lactation. Average milk production was reduced by 0.38 kg/degree C and average protein production was reduced by 0.01 kg/degree C. Elongation of daylight increased average milk production by 1.2 kg/h and average protein production by 0.02 kg/h of daylight. Analysis of the temperature pattern effect on milk and protein yield during lactation indicated that cows at the second month (the pike of their milk yield) are more vulnerable to the negative temperature effect than cows on the ninth month of lactation.

Abstract: Synthetic polymers such as water-soluble polyvinyl pyrrolidone (PVP), water-insoluble polyvinyl polypyrrolidone (PVPP), and water-soluble polyethylene glycol (PEG) contain sufficient oxygen molecules in a chain to form strong hydrogen bonds with the phenolic and hydroxyl groups in tannins. This review deals with the practical uses of tannin-binding agents, particularly PEG, in tannins assays and for determining the negative effects of tannins on feed intake and digestion in ruminants. A gravimetric method to assay tannins by precipitation with PVPP is specific for tannins and does not require standards. The extractability of tannins from plant tissues can be reduced by drying samples at temperatures above 50°C and is dependent on many other factors, such as content and types of plant proteins. Therefore, it is not feasible to recommend a single, optimal protocol for all plant samples. A method to assay tannins which is based on measuring the amount of binding of PEG to plant samples was shown to be simple and accurate. It can also overcome some of these extractability problems. The following biological effects of tannins were investigated in studies where tannin anti-nutritional effects were partially or completely neutralised by varying levels of PEG supplementation. (1) Effects on appetite: the negative effects of tannins on appetite can occur in the short-term (within 20�60 min) and the long-term (days and weeks). Astringency and adverse postingestive influences of tannins on the epithelium of the oral cavity and the foregut cause short-term effects on food intake. Long-term effects can be related to reduction in the concentration of ammonia and volatile fatty acids (VFA) in rumen fluids, which can in turn serve as metabolic cues for deficiency of nitrogen (ammonia), energy (VFA), or both. (2) Effects on digestion: increasing content of tannins in foliage can be associated with an increase in bound protein and with reduced degradation rate of the degradable matter in the rumen, but there is no corresponding increase of the non-degradable fraction. Consequently, organic matter, protein, and cell wall digestibility are inversely related to tannin concentrations. (3) Inducing digestive responses: if a significant amount of tannins reach the duodenum, they may markedly reduce the intestinal activity of pancreatic enzymes (trypsin and amylase) and amino acids absorption from the intestine. Condensed tannins can also reduce the content of fluid and particulate matter in the rumen, accelerate the passage of liquid from the abomasum, and delay the passage of digesta in the intestine. The overall effect is a delay in the passage of fluid and particulate matter throughout the entire gastrointestinal tract. It is hypothesised that these responses are largely the consequence of the interaction of tannins with digestive enzymes and the epithelium lining the digestive tract.

Abstract: The present work studied the effects of tannins in carob leaves (CL) on rumen volume and kinetics, and on the retention time of fluid and particulate components of the digesta along the gastrointestinal tract (GIT) in goats. The experimental design was a two factor crossover experiment, i.e. in phase 1, two goats were fed CL and 2 CL and polyethylene glycol (PEG) and in phase 2, the treatments were switched. The main effects of tannins were depression of the rumen fluid and particulate content of the rumen, acceleration of the passage of liquid from the abomasum, and delay of the passage of digesta in the intestine. The overall effect was a delay in the passage of fluid and particulate matter throughout the entire GIT. It is hypothesised that these responses are largely the consequence of the interaction of tannins with digestive enzymes and the epithelium lining of the digestive tract.

Abstract: Goat living in harsh environments represents a climax in the capacity of domestic ruminants to adjust to such areas. This ability is multifactorial: low body mass, and low metabolic requirements of goats can be regarded as an important asset to them for it minimise their maintenance and water requirements, in areas where water sources are widely distributed and food sources are limited by their quantity and quality. An ability to reduce metabolism allows goats to survive even after prolonged periods of severe limited food availability. A skillful grazing behaviour and efficient digestive system enable goats to attain maximal food intake and maximal food utilisation in a given condition. There is a positive interaction between the better recycling rate of urea and a better digestion of such food in desert goats. The rumen plays an important role in the evolved adaptations by serving as a huge fermentation vat and water reservoir. The water stored in the rumen is utilised during dehydration, and the rumen serves as a container, which accommodates the ingested water upon rehydration. The rumen, the salivary glands and the kidney coordinately function in the regulation of water intake and water distribution following acute dehydration and rapid rehydration. Goats in the tropics, when possible, eat a diet composed of tree-leaves and shrubs (browse), which ensure a reliable and steady supply of food all year around, albeit, from a low to medium quality food. Some of the physiological features of ruminants defined as intermediate feeders like large salivary gland, the large absorptive area of their rumen epithelium, and the capacity to change rapidly the volume of the foregut in response to environmental changes are most likely responsible for the goat�s superior digestion capacity

Abstract: Abstract A single daily oral dose of polyethylene glycol (PEG) � a tannin-binding agent � has been shown to substantially improve feed intake and efficiency of utilization by sheep and goats consuming tannin-rich forage. The aim of this study was to quantify the effect of supplementing 10 g/day of PEG on the performance of does grazing on Mediterranean woodland and scrubland. The experiments were carried out in production systems based on Mamber goats raised only for the production of slaughter kids (Experiment 1), dual-purpose Mamber goats raised for slaughter kids and milk (Experiment 2) or Damascus�Anglo-Nubian goats raised mainly for milk (Experiment 3). In Mamber goats, PEG supplementation was associated with higher body weight (BW) gain during pregnancy (p<0.01), higher kid birth-weight (p<0.05) and daily BW gain until weaning (p<0.10 and p<0.05 in Experiments 1 and 2, respectively), and no difference in milk yield. In contrast, the response of Damascus�Anglo-Nubian goats to PEG was a 43% increase in milk yield (p<0.001) but no response in kid weight at birth. These responses are consistent with previous findings that show the resilience of Mamber goats to practices aimed at increasing their milk production while these goats respond well to practices that improve the probability of successful reproduction in harsh environments. In contrast, Damascus�Anglo-Nubians respond to increased available nutrients by increasing their milk production. Supplementation with PEG has the potential to improve the profitability of systems in which liberally supplemented and high-yielding dairy goats feed on Mediterranean browse. However, its contribution to production systems exploiting well adapted but low-yielding local goats is limited.

Abstract: The ability of adrenocorticotrophic hormone (ACTH; single i.v. injection of 2.5IU/kg BW) and dexamethasone (single i.m. injection of 36mg/kg BW) to affect milk production was studied in mid-lactating Israeli Saanen goats. None of these treatments produced changes in milk yield and composition of the goats. The effects of ACTH on blood cortisol levels, and the effects of ACTH and dexamethasone on blood plasma concentrations of glucose, however, were consistent with previous reports in goats and cows. These responses suggest that ACTH and dexamethasone treatments produced their expected glucocorticoid effects. It is suggested that obstructing the axis: stress-ACTH-glucocorticoid-down regulation of milk yield, which was demonstrated in dairy cows, reflects the adaptation of goats to harsh conditions, and the selection pressure to produce milk under conditions which are considered stressful for other ruminants.

Abstract: Stress and stress related hormones such as glucocorticoids inhibit lactation in cows. In the present study we propose a novel mechanism connecting stress with plasminogen-plasmin system (PPS) (an enzymatic mechanism in milk, which leads to the breakdown of the major milk protein casein). We show that stress activates the PPS leading to an increase in plasmin activity, and that a distinct plasmin-induced beta-casein breakdown product (fraction 1-28) is a potent blocker of potassium channels in mammary epithelia apical membranes. The reduction in milk production due to dehydration stress or glucocorticoid (dexamethsone) was correlated with the activities of plasmin and channel blocking activity in the milk of the tested cows. The notion that the axis Stress-PPS-beta-casein fraction 1-28 is responsible for the reduction in milk yield is supported by the results of experiments showing that injecting solution composed of casein digest enriched with beta-casein fraction 1-28 to the udder lumen leads to a transient reduction in milk production. Furthermore, injecting a pure beta-casein fraction 1-28 to the udder lumen of goat's lead also to a transient reduction in milk production with kinetics that was similar to the kinetics observed in cows.

Abstract: Ingestion of condensed tannins decreases feed intake in ruminants. Polyethylene glycol (PEG) forms high-affinity complexes with tannins. In two experiments carried out on Holstein heifers, quebracho (Q) from the Aspidosperma quebracho served as source of condensed tannins. The aims of the study were (i) to quantify the effect of Q on feed intake and eating behaviour in cattle fed complete mixed diets (CMDs); (ii) to clarify if changes induced in ingestive behaviour and feed intake by Q in cattle can be reversed by feeding PEG; and (iii) to clarify if the decrease in feed intake is associated with short-term (astringency, post-ingestive malaise) or longer-term effects. In experiment 1, 500 g/day of Q was found to be the minimal dose that decreased feed intake in heifers. A ratio of PEG:Q equal to 1:12.5 did not fully restore feed intake. In experiment 2, four heifers received a random sequence of four rations in a Latin-square design with feeding cycles of ca. 7 days: CMD containing no supplements (C), or supplemented with 625 g/day of Q without PEG (Q), with 625 g/day of Q and 250 g/day of PEG (Q-PEG), or with 250 g/day of PEG without Q (PEG). Individual rations were continuously weighed in the trough and the behaviour of heifers was observed for 180 min after distribution of CMD. Overall, feeding Q was associated with lowered feed intake and shorter duration of eating bouts, mainly of the first eating bout, immediately after distribution of the diet. A larger portion of the diet was consumed subsequent to 180 min after distribution in Q-fed heifers. Eating rate and the water to food ratio were not affected by Q. The effects of Q on feed intake were attenuated by feeding PEG. Heifers adapted effectively to condensed tannins by increasing the number of eating bouts and the portion of diet consumed subsequent to 180 min after distribution, so that no differences in feed intake were noted on the last day of each feeding cycle. Data are interpreted to show that: (i) negative effects of Q on feed intake derive from astringency of CT and short-term post-ingestive malaise; (ii) the increased number of eating bouts and their wider partition throughout the day are means to preserve the ruminal environment in Q-fed heifers; (iii) PEG has the potential to neutralize negative effects of condensed tannins in cattle.

Abstract: Supplemental polyethylene glycol (PEG) increases intake when animals eat foods high in tannins, but little is known about how PEG affects preference for foods that vary in concentrations of macronutrients and tannin. We investigated how varying macronutrients and tannins (commercially available extracts from quebracho trees) affected food intake, and we assessed the degree to which PEG (MW 3350) affected intake of tannin-rich foods by sheep. From 0715 to 1800 daily, lambs were offered diets that varied in concentrations of macronutrients: high energy/low protein (75% barley/25% alfalfa), medium energy/medium protein (35% barley/65% alfalfa), and low energy/high protein (100% alfalfa). Preference for these diets was determined in the absence of tannin, and then, in Trials 1 to 3, tannin was added in increasing concentrations (from 5 to 20%) to the diets with high and medium levels of energy. In Trial 4, tannin (10%) also was added to the low-energy diet. Lambs were supplemented with either 50 g of PEG mixed with 50 g of ground barley or 50 g of ground barley alone from 0700 to 1715 daily; lambs always consumed all of these supplements. In the absence of added tannins, all lambs preferred high energy/low protein > medium energy/medium protein > low energy/high protein. As tannin levels increased, preference for the high- and medium-energy foods decreased, and all lambs preferred foods that were lower in tannins and higher in protein. Lambs supplemented with PEG ate more macronutrients and tannins than unsupplemented lambs, and the effect became increasingly apparent as tannin levels increased from Trials 1 to 4. We conclude that the effectiveness of supplemental PEG may be low if alternative forages are equal or superior in nutritional quality and contain fewer metabolites with adverse effects. In such cases, animals would likely prefer alternatives to high-tannin foods.

Abstract: Tannins occur in many plant species, and they often suppress intake by reducing nutrient availability or by causing malaise. Polyethylene glycol (PEG) binds to tannins and may thereby increase the availability of macronutrients and decrease malaise. Supplemental PEG increases intake of tannin-containing plants by sheep, goats, and cattle. Given the strong response to supplemental PEG, we speculated that animals might self-regulate their intake of PEG when offered foods high in tannins. The objective of the first experiment was to determine if the amount of supplemental PEG (0, 25, 50, 75, or 100 g; molecular weight, 3,350) affected intake by lambs of a food (milo-tannin mix) containing 20% quebracho tannin. There was a linear relationship (Y = 272 + 1.2X; R2 = .86; P = .023) between the amount of supplemental PEG ingested and the subsequent intake of milo-tannin food by lambs. The objective of the second experiment was to determine whether lambs self-regulated intake of PEG when fed a ration that contained 0, 5, 10, 15, or 20% quebracho tannin and whether they adjusted their intake of PEG when tannin was removed from the diet. There was a positive relationship between the amount of PEG ingested and intake of food and tannin (P = .0001). Lambs fed high-tannin diets ate more PEG than controls (P = .03). Lambs fed the 20% tannin diet ate the most PEG, and controls ate the least PEG. Tannin limited intake of the diets, but PEG attenuated the response to a great degree (P = .065). Immediately after tannin was removed from the ration, lambs that formerly had been fed the 20% tannin ration ate more PEG than lambs fed the other rations (P = .0075). Ten of the lambs (5 from the 20% tannin group, 1 from the 15% tannin, and 2 each from the 10 and 5% groups) continued to eat PEG for 7 d after tannin was removed from their ration. When they were tested again 6 wk after the trial and offered tannin-free diets, their intake of PEG had decreased.

Abstract: Dexamethasone was injected in dairy cows in order to get a better insight into the effects of corticosteroids on milk secretion and composition. A single intramuscular dose of 40 mg dexamethasone caused a 45% reduction in milk yield after 24 h; full recovery took 5 d. The secretion of fat, casein and magnesium was not affected by the treatment, Consequently, the concentration of fat, total protein, total casein, magnesium and phosphorus increased then decreased in direct proportion to the changes in milk yield. The secretion of total protein, calcium and phosphorus decreased as a result of the treatment. The concentration of lactose and the monovalent ions (sodium, potassium, and chlorine) was unaffected, and as a result their secretion decreased and returned to pretreatment level in direct inverse proportion to the changes in milk yield. Whey protein secretion decreased for 48 h and was responsible for the decrease in total protein secretion for 48 h. The most profound effect of dexamethasone is the reduction in the secretion of the osmotic components.

Abstract: How the interactions among heat stress, calving season and milk yield (MY) affects lactation and body weight (BW) curves was studied by analyzing the daily records of MY and BW of dairy cows. The summer calving cows (SC) attained minimal BW sooner than winter calving cows (WC), the differences between high yielding (HY; MY greater than or equal to 40 l/d) SC and WC being greater than differences between low yielding (LY; MY<40 lid). The minimal BW was lower in all SC than in WC and this could be related to the differences between the HY cows. MY peak was higher in all WC than in all SC, similar in LY cows among the two treatments, and higher in HY WC than in HY SC. The 4.4% differences in MY during the first 40 wk postpartum between all WC (8960 l) and all SC (8568) could be related to 8.0% differences between HY WC (10444 l) and HY SC (9604 l). During the summer peak MY occurred later than during the winter irrespective of the production level. We have shown that heat stress during early lactation affects the entire lactation and BW curves in dairy cows, and that heat stress negatively interacts with MY.

Abstract: High ambient temperatures, high direct and indirect solar radiation, and humidity are environmental stressing factors that impose strain on animals. This review concerns the heat stress�strain response of domestic ruminants from the viewpoint of animal welfare. Despite having well developed mechanisms of thermoregulation, ruminants do not maintain strict homeothermy under heat stress. There is unequivocal evidence that hyperthermia is deleterious to any form of productivity, regardless of breed, and stage of adaptation. The best recognized effect of raised body temperature is an adaptive depression of the metabolic rate associated with reduced appetite. Thus, in domestic ruminants a rise of body temperature marks the transition from aversive stage to noxious stage. Physiological (sweating, panting), hormonal (cortisol, thyroid gland activity), and behavioral thermoregulatory responses are discussed in respect to animal welfare. Factors such as water deprivation, nutritional imbalance and nutritional deficiency may exacerbate the impact of heat stress. The higher sensitivity of cattle to heat stress in comparison with sheep, and of animals at various productive stages in comparison with animals at maintenance is highlighted. Some practical measures that are applicable under extensive conditions, such as provision of shade shelter, are suggested.

Abstract: Browse and cereal stubble represent the two most important resources for grazing small ruminants in dry Mediterranean areas. The purpose of the present review is to provide updated information regarding their nutritional value. In a mixed Mediterranean environment, browse represents at least 40% of goat�s diet. Most browse species in the Mediterranean are rich in tanniferous phenolic substances. Polyethylene glycol (PEG) can bind tannins irreversibly over a wide range of pH and is efficient in alleviating the negative effects of tannins. Supplementing with PEG improves intake and digestibility in grazing goats and sheep and has the potential to be economically profitable. The chemical composition of wheat stubble is affected by the cultivar of wheat and climate, but not tillage management. The quality of stubble from early maturing is lower than from late maturing cultivars. Stubble contains more protein in years of lower rainfall. If grains escaped from the harvest combine (2% of grain yield) are included, digestibility of OM from different components ranges between ±80% (grain) to ±40% (stem). Also, the energy requirement of sheep grazing on stubble may be 70% higher than in shaded feedlot. Therefore, the body condition changes of sheep grazing on stubble exhibit a cyclic pattern consequent with temporal changes in nutritive quality. Because stubble grazing is concurrent with the onset of oestrous season, supplementation with grains from legume species-rich in degradable protein-is needed to prevent impairment of body condition. Supplementing browsing goats with PEG, and sheep grazing cereal stubble with moderate amounts of legume grain, may enable the use of these traditional resources in the frame of sustainable production systems.

Abstract: Posthatched naive or inoculated male broiler chicks were kept in separate rooms. An inoculum was prepared from intestines of stunting-syndrome affected broiler chicks. Tap water was supplied from 2 L cups, 1 cup per pen. In the Ist experiment, the naive chicks were provided with tap water only and the inoculated ones had free access to tap water or to an electrolyte solution. In the 2nd experiment, the naive and inoculated birds had free access to water in addition to an electrolyte solution. Supplementation was provided up to 3 weeks of age; thereafter all chicks had access to tap water only. Water or electrolyte consumption and body weight (BW) were determined. Total water intake of inoculated chicks was higher than that of naive counterparts (P<0.001). Electrolyte supplementation increased drinking (P<0.001) in inoculated birds more than in naive ones. At 1 week old the weight of the inoculated birds was about 64% of the weight of naive ones; at the age of 4 and 6 weeks it was about 74% and 86% respectively. Compensatory growth was most apparent in the inoculated chicks provided with electrolyte solution. At the age of 6 weeks, the latter exceeded the BW of the exclusively water supplied counterparts by 327 g. Electrolyte supplementation up to the age of 3 weeks had no effect on the naive counterparts. Osmolality was reduced slightly, but very significantly by inoculation; electrolyte supply had no effect on this variable. Sodium concentration in the plasma was higher in the inoculated birds. Plasma albumin was markedly reduced by inoculation on weeks 1 and 2. Whereas the inoculated chicks supplied with electrolytes resumed the level plasma albumin level of the naive chicks on week 3, an over-compensation occurred in the inoculated-water-supplied (IW) group, and they surpassed the naive chicks significantly. Blood hematocrit increased significantly with age; inoculation, age and/or electrolyte supplementation had no effect on this variable. Sodium-dependent glucose transport rates were enhanced in vesicles obtained from inoculated chicks as compared to naive ones. While electrolyte supplementation had no effect on glucose active transport in naive chicks, electrolyte supplementation decreased rates of glucose active transport in inoculated ones. These data demonstrate that electrolyte supplementation during the early age may be used to enhance the tolerance of broiler chicks to stunting-syndrome by improving food and water consumption, and subsequently growth rate during and after cessation of electrolyte supply.

Abstract: We found previously that the current recommendations for Na+, K+, and Cl- contents in the diet do not meet the needs of lactating cows. The response of cows receiving a ration with increased amounts of Na+, K+, and Cl- (E cows) were compared with those of cows consuming the same ration with a fixed concentration of these ions (C cows) between weeks 2 and 8 post partum (PP). Milk, protein, fat and lactose yields, and dry matter intake between weeks 2 and 4 PP were higher in E than in C cows. These differences did not occur between weeks 4 and 8 PP, mainly because of a higher incidence of PP complications in E cows. A greater increase in plasma insulin-like growth factor-1 concentration in E than in C animals during weeks 2 and 3 PP was consistent with the milk responses. A reduction in aldosterone concentration in E cows in weeks 2 and 3 PP was a consequence of their Na+ requirements being satisfied as a result of their enhanced Na+ intake. A subsequent elevation in aldosterone concentration in E animals was probably related to a moderate excess in K+ intake. This increase in aldosterone explains the urinary potassium loss that was detected at week 6 PP. The absence of differences between E and C cows in plasma renin activity was consistent with an absence of differences in urine volume and with the apparent utilization of the enhanced ion intake for body functions.

Abstract: Three compartmental models were developed to evaluate the suppressive effects of tannins on the extent and rate of degradation of tree foliage. The first model was based on the assumption that tannins modify the parameters of the degradation kinetics, the second was based on the assumption that tannins bind material, independent of the basic degradation kinetics, and the third combined these two assumptions, i.e., that tannins both suppress degradation and bind free material. Degradation was measured by suspending the samples in dacron bags in the rumens of goats, with or without the inclusion of polyethylene glycol (PEG). It was assumed that PEG annuls the suppressive effect of tannins on degradation of plant components, and hence that the difference between the curves that describe degradation with or without PEG indicates the suppressive effect of tannins present in the foliage. The data on the observed degradation of dry matter, neutral detergent fibre and protein, in four typical Mediterranean forest tree species were fitted by these models. It was found that the combined model fits the data better than either of the other two models. Increasing content of tannins in the foliage was associated with an increase of the bound free material and a decrease in the degradation rate of the degradable matter, but not with an increase of the non-degradable fraction.

Abstract: Goats indigenous to tropical and subtropical environments generally performed better than other ruminants in terms of survival, reproduction and expression of their genetic potential for growth and milk yield. These advantages are emphasized in case of successive years of drou ht, a typical event in the dry belts of the subtropics. Low body weight (BW) and low metabolic rates per BWO"'allow desert goats to maintain a frugal energy and water economy. Some of the desert breeds, such as the Bedouin goats, are able to reduce their energy requirements by as much as 65% in response to reduction in feed availability. The digestibility of dry matter and structural carbohydrates found in some breeds of desert goats fed on highly-lignified diets exceeds considerably that observed in non-desert goats and other domesticated ruminants. The capacity of goats to consume high-tannin browse and to detoxify the tannin is higher than that found in sheep and cattle under comparable conditions. These advantages are probably related to the ability of goats to control effectively their rumen environment. Maintaining a spacious rumen allows a longer retention time of feed particles without negatively affecting feed intake. In addition, maintaining a steady pH in the rumen, and efficient recycling of key nutrients such as nitrogen and sulfur, enable goats to maintain a maximal. ruminal fermentation rate at given conditions. In Mediterranean areas, goats exhibit a preference for browse even when plenty of green grass is available during spring. This behaviour is justified on the long run because plenty of browse is available all year around. Adaptation to high-tannin feed is a long-time process that allows goats to benefit from a steady supply of forage. Key words: Animal performance, harsh environment, goats, review. RESUME - "Pourquoi les caprins �lev�s en milieu difficile ont de meilleures performances que d'autres animaux domestiques". Les caprins autochtones des environnements tropicaux et subtropicaux ont g�n�ralement de meilleures performances que d'autres ruminants en termes de survie, reproduction et expression de leur potentiel g�n�tique pour la croissance et le rendement laitier. Ces avantages sont accentu�s dans le cas d'ann�es successives de s�cheresse, un �v�nement typique dans les ceintures s�ches subtropicales. Un faible poids une �conomie frugale de l'�nergie et de l'eau. Certaines des races du d�sert, comme les caprins des B�douins, sont capables de r�duire leurs besoins en �nergie de jusqu'� 65% en r�ponse � la r�duction des disponibilit�s en aliment. La digestibilit� de la mati�re siche et des hydrates de carbone structurels que l'on rencontre chez certaines races caprines du d�sert recevant des r�gimes hautement lignifi�s, d�passe consid�rablement ce que l'on observe chez les caprins n'appartenant pas au d�sert et autres ruminants domestiques. La capacit� des caprins de brouter des arbustes riches en tannins et de les d�toxifier est bien plus grande que chez les ovins et bovins sous des conditions comparables. Ces avantages sont probablement li�s � l'aptitude des caprins de contr�ler effectivement leur environnement ruminal. Le fait d'entretenir un rumen spatieux permet un temps de r�tention plus long des particules alimentaires sans affecter n�gativement l'ingestion alimentaire. En outre, le fait de maintenir un pH r�gulier dans le rumen, ainsi qu'un recyclage efficace des nutriments fondamentaux tels que l'azote et le soufre, permet aux caprins de maintenir un taux maximum de fermentation ruminale sous certaines conditions. Dans les zones m�diterran�ennes, les caprins montrent une pr�f�rence pour le broutage m�me si une herbe verte abondante est disponible pendant le printemps. Ce comportement est justifi� � long terme car il y a abondance d'arbustes � brouter pendant toute l'ann�e. L'adaptation � une alimentation riche en tannins est un processus de longue haleine qui permet aux caprins de b�n�ficier d'un approvisionnement r�gulier de fourrage. Mots-cl�s : Performances animales, environnement difficile, caprins, r�vision. l corporel et des taux m�taboliques faibles par poids crporeP'permettent aux caprins du d�sert de maintenir Introduction Under desert and tropical environments, where feed resources are restricted in quantity and limited in quality, differences among ruminants in energy requirements and digestive efficiency, which 185 CIHEAM - Options MediterraneennesSerie A: Seminaires mediterraneens

Abstract: The regulation of milk constituents, synthesis and secretion in tissue cultures of the bovine mammary gland was altered by a whey fraction of bovine milk. alpha-Casein gene expression, casein secretion and fatty acid synthesis were inhibited by the whey fraction in a dose-dependent manner. The whey fraction inhibited the enhancement activity of prolactin on alpha-casein gene expression and fatty acid synthesis, and also inhibited casein secretion to the medium, in explants cultured in a medium with or without prolactin. No effect on the expression of the beta-lactoglobulin gene was found.

Abstract: Groups of nine or ten cows were assigned, after calving, to treatments in which they were (i) machine milked three times daily (M3), (ii) machine milked six times daily (M6) or (iii) suckled three times daily in addition to being machine milked three times daily (S). Treatments were administered during the first 6 weeks postpartum On one day, at weeks 1 and 6 postpartum, blood samples were collected from all cows at 30-min intervals between 06.00 and 13.00 h and these were analysed for plasma osmolality and plasma concentrations of Na+, K+ and Cl-. Milk yield was significantly higher in suckled cows than in cows milked six times daily, but significantly lower in cows milked three times daily. In cows milked six times daily, and to a greater extent in suckled cows, there was a reduction in plasma osmolality and monovalent ion concentrations (Na+, K+ and Cl-), which could increase the susceptibility of the cows to water intoxication. Moreover, suckling or milking the cows six times daily was associated with increased fluctuations in plasma osmolality and plasma Cl- concentrations. The decrease in plasma osmolality and ion concentration and the increased variation in plasma osmolality and Cl- were probably related to increased water intake and may be indicative of a severe challenge to homoeostasis regulation.

Abstract: Effects were studied on food intake and diet apparent digestibility of giving to gents once daily a basal diet rich ill tannin from inclusion of leaves of Quercus calliprinos either supplemented with a high carbohydrate or a high protein food. Also interactions with polyethylene glycol (PEG) were investigated. The results of the present work confirmed our presumption that the content of tannin in some Mediterranean browse is so high that it may negatively affect the utilization of Protein in supplementary foods. Neutralizing the tannins with once-daily provision of PEG proved to be nn effective means of pl eventing the negative effect. Providing 10 g/day PEG to gents given Quercus calliprinos leaves ad libitum and supplemented with 300 g/day concentrates containing 160 g crude protein per kg DM increased digestible crude protein intake by 50 g/day. When the concentrate food was given to goats, leaf dry-matter intake decreased significantly (from 664 to 565 g/day) and the gents lost weight rapidly. Therefore, supplementing tannin-rich leaves with concentrate food is recommended only if none in combination with PEG. High protein supplementation increased leaf(from 664 to 844 g/day) and digestible protein intakes (from 4.8 to 92.3 g/day) but a considerable portion of the protein supplementation tons wasted due to interaction with? tannins. PEG may allow economies in the use of such high-cost foods due to the greater efficiency?cy of protein utilization (digestible crude protein intake increased from 92.3 to 122 g/day) of the supplementary food and to increased intake and protein utilization of the basal leaf diet (from 844 to 1023 g/day).

Abstract: The concept that tannins in foliage reduce the voluntary intake of foliage by goats by evoking negative postingestive responses was examined. Meals and breaks between meals of goats fed high-tannin foliage were cyclic; the first meal within each cycle was the longest. Once-daily supplementation of polyethylene glycol (PEG) with a molecular weight of 4000, a tannin-binding agent, increased the duration of feeding activity and decreased the duration of breaks between meals. Tha cyclic feeding behaviour could be associated with development of food aversion due to interaction of tannins with the rumen epithelium.

Abstract: We studied the balance of Na+, K+, Cl-, and water in six high yielding (> 39 kg/d of milk) cows between wk 2 to 1 prepartum and at 2 and 7 wk postpartum during winter in Israel. Cows were fed complete diets; Na+ and Cl- contents exceeded dietary recommendations, and K+ content was equal to dietary recommendations. Milk yield was related positively and significantly to retention of Cl- and K+, indicating that ions that are the main constituents of sweat can limit the ability of cows to express full genetic potential. The highest ion retention was recorded for cows that had the highest dry matter intake and, hence, the highest ion intake. Retention of Cl- was highest for cows that were most efficient in retaining Cl- in the kidney. In hot climates, increasing the concentrations of ions in the diet of early lactation cows according to the actual dry matter intake could prevent or reduce the severity of ion deficiencies. Water turnover rate of the cows was dependent on dry matter intake, milk yield, and respiratory-cutaneous water loss. The milk-free water balance (water turnover rate minus water secreted in milk) could be very efficiently predicted for lactating and nonlactating cows by the following equation: milk-free water balance (kilograms per day) = digestible energy intake (megacalories per day) x 0.58 + respiratory-cutaneous loss (kilograms per day) x 0.97 (n = 18; R2 = 0.97). This formula provides a tool to assess the evaporative-cutaneous water loss from feed and water intake measurements to evaluate the severity of heat stress.

Abstract: The effects of birth month on production of milk, fat, and protein and percentages of fat and protein were analyzed based on production records of 101,653 first parity, 77,541 second parity, and 51,856 third parity Israeli Holstein cows. Each parity was analyzed separately. The analysis model also included the effects of herd-year, DIM, calving age, and calving month. First parity Type III sums of squares for birth month were nearly as large as those for calving month but decreased for later parities. Similar results were obtained using multiplicative models in which the dependent variables were the logarithms of the production traits. The effects of calving month and birth month were not similar, but birth month had similar effects for milk, fat, and protein production. Production was lowest by cows born in the early spring and highest by cows born in the fall. Analyses of the log-transformed traits showed that the F values for calving month were greater than, and the F values for birth month were nearly identical to, the F values for the untransformed trait analyses. The physiological basis for these trends was not clear.

Abstract: The balance of water, Na+, K+, Cl-, and total solute in the kidney and the N balance of the whole body were measured for six high yielding cows at 2 wk prepartum (period 1) and at 2 wk (period 2) and 7 wk (period 3) postpartum during winter and autumn in Israel. The onset of lactation was not followed by an increase in glomerular filtration rate and urine volume. To meet the deficiency in Na+, K+, and Cl- ions, the kidney conserves them during early lactation, mainly by increasing tubular reabsorption. An interdependent relationship exists between the excreted urea and nonurea solutes. Thus, reduction of ion concentrations in urine during early lactation reflects both the need to excrete a large load of urea and the effort to conserve Na+, K+, and Cl-. The high load of urea during early lactation was a result of a negative N balance that was most likely related to a negative energy balance. We concluded, through a comparison of our results with those of a similar study during summer, that the role of the kidney in ion conservation is more pronounced during summer than during winter and that the recovery of cows from a negative balance of energy and N is faster in summer than in winter.

Abstract: A procedure to measure poly(ethylene glycol) (PEG) binding to plant samples is described. The amount of PEG bound to a sample was found to be reproducible with a small coefficient of variation (0.5%). The PEG-binding capacity of plant samples was not affected by predrying of the samples at 90 °C, unlike the colorimetric methods for determination of tannins. Both the PEG-binding and the protein precipitation capacity of the plant samples were found to be useful in predicting the negative effects of tannins on ruminal degradation of the plant material. However, PEG binding to plant samples had an advantage over protein precipitation in samples in which formation of strong tannin�protein complexes results in low extractability of tannins. For this reason, the binding method was found to be preferable to the protein precipitation method in predicting the negative effect of tannins on ruminal degradation of forage plants.

Abstract: AbstractIntake and digestion of leaves of Quercus calliprinos, Pistacia lentiscus, and Ceratonia siliqua, with and without supplementation of various amounts of polyethylene glycol (PEG), were examined. The tannin contents in these species exerted a substantial negative effect on feed intake and digestion. The effects were species specific and related to tannin content. Once-daily Supplementation with PEG efficiently neutralized the negative effects of tannins. The amount of PEG needed to produce a maximal increase in feed intake was lower than the amount required to produce a maximal increase in digestibility. The intake of digestible crude protein and metabolizable energy was raised in PEG-supplemented animals from a submaintenance level to levels considerably exceeding the maintenance requirement of goats. The response was related to the tannin content of the plant.

Abstract: The blood metabolic profile was examined in 2�3 year old non-lactating and non-pregnant Mamber goats consuming Quercus calliprinos (oak), Pistacia lentiscus (pistacia) and Ceratonia siliqua (carob) leaves to determine whether intake of tannin-rich fodder induces subclinical systemic toxicity. Total phenolic and condensed tannin content ranked in the order pistacia > oak > carob. Goats did not exhibit toxic effects following consumption of 10�23 g kg�1 day�1 of tannin-rich leaves. Metabolite blood concentrations did not differ from goats fed wheat straw, and were within the normal range. Certain serum metabolic indices that are known to be sensitive indicators of damage to the liver (gamma glutamyltranspeptidase, alkaline phosphatase, cholesterol) and kidneys (urea, uric acid, minerals) were within the normal range for goats. Thus, it appears that goats used in this study were well adapted to the nutritional environment and may consume large amounts of tannins (1.1�2.7 g per kg BW per day condensed tannins and 0.4�0.9 g kg�1 BW day�1 soluble phenolics) without suffering any ill effects.

Abstract: The presumption that water, Na, K, and Cl homeostasis is affected by the initiation of lactation, especially in hot weather, was examined. The study was conducted using five Israel Holstein cows at 1 to 2 wk before parturition (period 1) and at 2 wk (initiation of lactation) and 7 wk (established lactation) postpartum (periods 2 and 3, respectively). In period 1, most water intake was related to feed (in the absence of overt Na or osmotic stimuli). In contrast, during lactation, drinking was probably a combined response to feed-related and hypertonicity stimuli. Diurnal fluctuations in plasma ions, frequency of drinking, and volume ingested at each drinking increased postpartum. In period 2, plasma ion concentrations still were regulated around mean values, which was not the case in period 3, during which large diurnal variation in mean values occurred. The lowest values and highest variabilities were recorded in period 3 at midday. With the transition from the dry period to lactation, plasma concentrations of Na and Cl were reduced and became more labile, but the relationships between them remained stable. Plasma K seemed to vary independently of the two other ions. The reduced homeostatic efficiency of plasma ions during early and established lactation in hot weather may have consisted of an accumulation of their deficiencies, enhanced excretion of K in sweat, and sequestration of Na and Cl in the rumen.

Abstract: The nutritional value of carob leaves (CL) and the effectiveness of increasing amounts (12.5,25,32, and 50 g/day) of polyethylene glycol 4000 (PEG) supplemented once daily in overcoming the negative effect of tannins in carob leaves, were examined in four Merino ewes. Ewes fed solely CL were not able to sustain their body weights, and excreted in feces more protein than was consumed; the digestibility of cell walls was very low (220 gkg). Supplementation with 25 g/day PEG increased digestible organic matter intake by 2-fold. This increase was associated with a marked improvement in protein and cell wall digestibility and recovery of weight loss. The present results provide evidence for the first time that condensed tannins may induce a marked depressive effect on the intestinal activity of trypsin and amylase in ruminating animals (as indicated by their activity in fecal samples).

Abstract: Cotton straw (CS) and cotton straw stored as silage-like materials (CSS) were treated with alkaline peroxide solution, using either NaOH or CaO (lime) as a source of alkali, in order to increase its biodegrability. A 50�58% reduction in the lignin content was reflected by a twofold increase in the E280 of the reaction solution. In-vitro organic matter digestibility increased from 16 to 20% in untreated material to 61�64% after the treatments. Although the extent of delignification was greater when NaOH was used as a source of alkali, in-vitro dry matter digestibility of the treated straw simlar for the two treatments.

Abstract: The effects of hyperhydration, induced by oral loading via a stomach tube (41 of 0.9% NaCl within 2-3 min), intra-peritoneal and intra-jugular infusions (41 of 0.9% NaCl solution at a rate of 21 hr-1) in normally hydrated goats, on fluid retention, plasma expansion, kidney function and drinking response were compared. Higher fluid retention (67 and 65% vs. 40% at 3 hr after the termination of the infusion, P < 0.01), attenuated diuretic (P < 0.01) and natriuretic (P < 0.01) responses and lower expansion of plasma volume (P < 0.05) were recorded in the orally and intra-peritoneally treated goats in comparison with the intra-jugularly treated animals. Portal expansion apparently induces acceleration of saliva secretion which recycles water to the gut. Recycling of water to the gut reduced excessive expansion of plasma fluid and load on the kidney. Retention of water in the rumen satiated the urge to drink in the orally and intra-peritoneally treated goats for at least 24 hr. The intra-jugularly treated goats consumed a significant amount of water (1l), which was approximately half of their normal requirement. Under arid conditions, these responses are appropriate to the animals' regular exposure to severe dehydration and rapid rehydration.

Abstract: Ruminants in tropical and desert areas routinely experience cycles of severe dehydration and rapid rehydration. These animals can withstand severe dehydration (18-40% of initial body weight), which exceeds considerably the capacity of most monogastric mammals. This capacity is related to their ability to use, during the course of dehydration, their large water reservoir in the rumen, which contributes 50-70% of the total water loss. As rumen fluid is in approximate isotonicity with systemic fluid, the utilization of gut water during the course of dehydration involves a considerable load of sodium and potassium. Consequently, the effectiveness of utilization of rumen fluid during dehydration depends on the capacity of the kidney to 'desalt' the water absorbed from the gut and on maintenance of salivary flow to the rumen. Following rehydration, ruminants can imbibe their entire water deficit in one drinking and the entire amount ingested is first retained in the rumen. The rumen volume at this stage may exceed the extracellular fluid volume and the sudden drop in rumen osmolality creates a huge osmotic gradient (200-300 mosmol kg-1) between the rumen and systemic fluid. Ruminant animals are confronted at this stage by two opposing tasks, each of them of vital importance: (i) the need to prevent the osmotic hazard leading to water intoxication; and (ii) the need to retain the ingested water, so that it is not missing for the next dehydration cycle. The most prevalent view until recently was a theory which attributes an osmotic protective mechanism to the rumen wall. However, such a capacity has not yet been demonstrated and is challenged by contradictory observations that large amounts of water are absorbed from the rumen following rehydration. The view that is most consistent with available information is that gustatory-alimentary and hepatoportal signals regarding the presence of large amounts of water in the rumen and the absorption of water from the gut activate a range of homeostatic responses involved in fluid and sodium restitution. The efferent elements, presumably activated by the CNS, include: a dramatic increase in secretion of hypotonic saliva and, reciprocally, a dramatic drop in urine flow. The enhanced saliva secretion recycles a considerable portion of the water absorbed from the gut back to the rumen, which allows effective retention of water while avoiding the danger of osmotic threat to the red blood cells. The enhanced saliva secretion also drains large amounts of sodium and bicarbonate from the blood. Accompanying responses are marked retention of sodium and carbonic acid in the kidney.(ABSTRACT TRUNCATED AT 400 WORDS)

Abstract: Fermentation and passage rate in the rumen and along the entire gut were measured in black Bedouin and Swiss Saanen goats fed a high fiber diet (Rhodes grass (Chloris guyana) supplemented with 10% alfalfa hay). The purpose of the study was to clarify the physiological basis that underlies advantages of Bedouin goats over non-desert goats in digesting high fiber based diets. Volume of fluid and rumen digesta particle distribution were similar for both breeds. Ability of Bedouin goats to consume amounts of hay equal to those consumed by Saanen goats, despite considerably longer retention time in the rumen, was related to their ability to maintain a higher digestion rate in the rumen. Microbial activity in the particulate fraction was higher in Bedouin goats than in Saanen goats, and this was reflected in total rumen fermentation, i.e., in significantly higher volatile fatty acid production rate and significantly higher volatile fatty acid concentrations. The ability of Bedouin goats to maintain a high fermentation rate in the rumen may be partially related to their ability to control rumen pH above levels which cause severe depression in rate of fermentation. The combination of higher fermentation rate and slower passage allows maximization of feed intake and digestibility in a given situation, as compared to non-desert ruminants.

Abstract: During clinical investigation of a commercial herd it was found that intake of supplemented poultry litter (PL) by beef cows at > 10 kg/day, was associated with severe cachexia and a mortality rate of between 10 and 20% of cows. Post-mortem analysis of 40 fresh carcasses and elevated serum levels of cholesterol, bilirubin, alkaline phosphatase, glutamic oxaloacetic transaminase and sorbitol dehydrogenase in cachectic cows indicated that the cows suffered severe liver damage. The interrelationship between liver damage and PL intake was subsequently investigated in three groups of 20 beef cows each, consuming 0, 3 and 10 kg PL respectively. As determined by the serum indices, intake of 3 kg PL seemed to be sufficient to cause liver damage, although these cows appeared healthy. In another experiment, six beef cows were stall-fed a diet giving separate access to PL and wheat straw. PL intakes were 3.1, 4.7 and 6.0 kg/day. Ruminal ammonia concentration was three to five times higher than the estimate of that required for maximal fermentation in the rumen. The high pH values (6.81 to 6.97) found are optimal for absorption of ammonia from the rumen. The combination of excess absorption of ammonia from the gut and low metabolizable energy intake might have been the cause of liver damage.

Abstract: The objective of the study was to assess the usefulness of providing shade for beef cows grazing summer dry Mediterranean pasture and supplemented with a food high in non-protein nitrogen (poultry litter). Two groups of 30 cows each, in the last trimester of pregnancy, were placed on 1 June in two paddocks of similar grazing pressure, topography, vegetation cover and botanical composition. In one of the sub-units the cows had free access to a large shaded area, provided by 10 to 12 large eucalyptus trees, whereas in the second sub-unit, access to shade was denied until 31 August. Respiration rate, used as an index of heat stress, was much higher in the non-shaded cows (102 breaths per min) than in the cows with access to shade (62 breaths per min). In response to the much higher heat stress in the non-shaded cows, total body water and haematocrit value (an index of plasma volume) were higher than in the cows with access to shade. Metabolizable energy (ME) intake was apparently much lower in the non-shaded cows, as reflected in a much higher non-esterified fatty acid concentration in plasma. Consequently, large differences in live weight gradually developed during the course of the trial, the cows with access to shade becoming much heavier than those with no access to shade. An increase in the consumption of poultry litter by the non-shaded cows was interpreted as an effort to reduce internal heat load by avoiding grazing and by preferring food which induces a lower heat increment upon ingestion and digestion. Above-normal serum concentrations of cholesterol and alkaline phosphatase support previous results that the combination of low ME intake and high ammonia load induces a toxic effect on the liver. Although all the cows were pregnant at the onset of the study, successful parturition was recorded in 26 of the 30 cows having access to shade, and in only 20 of the 30 (P < 0.05 by t test) of the non-shaded cows. It is concluded that providing shade for beef cows under summer Mediterranean conditions will reduce the danger of embryonic loss. However, an interaction with metabolic burden, such as ammonia load and a negative energy balance, can make the situation much worse.

Abstract: Abstract The purpose of the present review is to provide an integrated examination of the effects of infrequent drinking, water restriction, and heat load on feed intake and utilization in ruminants. The above-mentioned limitations reduce appetite and increase feed utilization. Reduction in rumen motility, rumination activity and saliva secretion reduce passage rate, and hence increase the digestibility of structural carbohydrates. However, contrary to a commonly held view, these digestive responses are directly related to the imposed stress, rather than secondarily related to reduction in feed intake. Although water deprivation, water restriction and heat load similarly affect appetite and digestion, the physiological basis of each is different. Water restriction does not disturb plasma tonicity and its effect is mediated by modification of the food-related drinking. Water deprivation effects are mediated through elevation of plasma osmolarity and secondarily through increase in gut fill and ruminal Na concentration. Heat load effect is mediated through elevation of body temperature and secondarily through increase in gut fill. The response to heat stress is more diverse, since heat load affects both the energy and water metabolism, and varies due to differences among ruminants in insulation properties and body size. As water scarcity and high temperatures are characteristic of dry areas, interactions exist between these two factors, and some examples are given. Goats, having poor insulation capacity, and sheep, with excellent insulation capacity, represent two physiological models. Breeds of ruminants which are well adapted to arid environments demonstrate a greater capability than nondesert breeds to ameliorate the stressful effects induced by water deprivation and heat load. However, as a general rule, the negative effects of water deprivation and heat stress override the benefits from increased feed utilization.

Abstract: Water, Na, K, and Cl balances, blood plasma composition, and urine and fecal outputs were studied in 5 high yielding cows (greater than 30 kg/d milk) at 2 wk prepartum and at 2 and 7 wk postpartum during the summer in Israel. Cows were fed complete diets with electrolyte content exceeding dietary recommendations. Plasma volume, as assessed by hematocrit changes, was greater postpartum, probably due to increased heat load and water turnover. Milk secretion markedly increased electrolyte output, which was compensated for only partially by increased intake. This was associated with marked reduction of electrolyte losses in excreta, particularly that of Na and Cl. On the basis of urea excreted in the urine, it seems that the current practice of abruptly increasing protein content of the diet at the onset of lactation might reduce the efficiency of dietary protein utilization, compared with efficiency of protein utilization at a later stage of lactation. The need to excrete excessive N also adversely affected the water and electrolyte balances. At initiation of lactation, when DMI is still limited and hot weather obstructs its rapid increase, the current recommendations for electrolytes as a percentage of the ration do not meet the needs.

Abstract: 1. In order to test the hypothesis that peripheral receptors are involved in the control of fluid re-distribution following acute dehydration and rapid rehydration, peripheral rehydrations (oral or intraperitoneal) were compared with central (intrajugular) rehydration. 2. The experiments were carried out with four goats dehydrated to about 20% of their initial mass. 3. Following peripheral rehydration, a higher proportion of water was retained in comparison with central rehydration, and this was related to a more effective kidney retention mechanism, i.e. lower GFR and higher tubular reabsorption. 4. Higher proportions of water were retained in the rumen in the peripheral rehydrations in comparison with the central one apparently due to increased saliva secretion. 5. Thirst saturation was more effective with the peripheral rehydration in comparison with the central one and was related to the amount retained in the rumen and to peripheral blood expansion (or dilution).

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Abstract: In vitro dry matter (DM) digestibility of green panic (Panicum maximum) dried to approximately 60% DM, treated with 30 g urea N kg�1 DM (UH) and left to be dried in an open stack was considerably higher than that of common panic hay (PH) (69% vs. 63%). The objective of the present study was to confirm these findings in vivo. Lucerne hay (LH) was added as a reference material. Urea treatment maintained lower neutral detergent fiber and lignin contents of green panic. Daily intake of digestible organic matter of UH (kg�1 W0.75), its digestibility (%), and its metabolizable energy (ME) density (Mcal kg�1 DM), were significantly higher than those of PH (49, 59 and 2.17 vs. 37, 57 and 1.97, respectively) and similar to those of LH. Nitrogen retention was highest in the UH treatment, indicating that some of the non-protein N was converted into microbial protein. Mean retention times (MRT) of digesta particles of PH, UH and LH in the entire digestive tract were 49, 42 and 35 h, respectively.

Abstract: This work was carried out to test the hypothesis that the high level of salivary secretion containing much Na+ and the volume of fluid sequestered in the foregut of ruminants play an important part in water and Na+ homeostasis. Saliva flow and composition and water and Na+ balance in the rumen have been measured in hydrated and dehydrated cows with esophageal fistulas. Reduction of voluntary feed intake in beef cattle during water deprivation was related to the stage of dehydration. Salivary secretion rate was linearly related to voluntary feed intake (r = 0.96) and inversely and linearly related to plasma osmolality (r = 0.88). The reduction in the volume of water stored in the rumen contributed to the major portion (55%) of the total water loss. Utilization of gut water attenuated the rise in blood plasma osmolality, and this may be connected with an animal's ability to continue eating despite dehydration.

Abstract: It has been shown recently that the circulation created by the continuous secretion of voluminous amounts of saliva rich in Na+ to the large store of fluid sequestered in the rumen and its reabsorption from the gut is an integral part of water and Na+ homeostasis in cattle. The role of this system in water and Na+ restitution following acute dehydration and rapid rehydration was studied. Cattle were able to withstand dehydration of 18% of their initial mass and to replenish their water losses in one drinking. The water imbibed was first retained in the rumen and slowly released. Rapid expansion (or dilution) of their blood as a result of large influxes of hypotonic water from the rumen was prevented by a parallel increase in the secretion of hypotonic saliva. The accelerated saliva secretion refluxed back to the rumen almost half of the water absorbed. Saliva electrolyte concentration varied simultaneously with an increase or decrease in saliva flow. Na+, HCO3-, HPO3-, and pH were inversely related to saliva flow rate while Cl and K+ were positively related. It seems that visceral afferent response was involved in activation of salivary flow rate.

Abstract: Intra- and interspecific relationships between energy intake and digestible energy intake (DEI) and water turnover (WTO) in Black Bedouin and temperate (Swiss Saanen) goats were analyzed. Available data from other species of mammals were also evaluated. A highly significant linear relationship between WTO and DEI holds within breeds of goats under different levels of DEI and between breeds which vary considerably in their body weight and metabolic expenditure (WTO ml/kg per day = -5.4 + 0.911 DEI kcal/kg per day, n = 34, r2 = 0.99, Sb = 0.057). In lactating goats the relation between WTO rate (minus water secreted in milk) and DEI is the same as that measured in non-lactating ones. Mammals with quite a different body weight have the same WTO per unit of metabolism--about 1 mol of water per 5 mol of oxygen--although their absolute turnover is very different. Furthermore, the above relationship is similar to the relationship between WTO:DEI found in goats here. (WTO ml/kg per day = 5.8 + 0.849 x kcal/kg per day, n = 8, r2 = 0.99, Sb = 0.030, where x is the caloric equivalent of oxygen consumption.

Abstract: Bedouin goats were fed on wheat straw as a single-component diet under two watering regimens, drinking once daily or once every 4 d, in order to clarify whether lignin-degradation products were absorbed, metabolized and excreted in urine. Acid-soluble lignin accounted for 220 g/kg total lignin, its digestibility was the highest (0.87) and was unaffected by water deprivation. Acid-insoluble lignin accounted for 780 g/kg total lignin and its digestibility increased during water deprivation from 0.21 to 0.41. Alkali-soluble lignin accounted for 320 g/kg total lignin and its digestibility increased during water deprivation from 0.44 to 0.53. Digestibility of structural carbohydrate was considerably higher than that observed in other domesticated ruminants fed on wheat straw. It responded positively to water deprivation, increasing from 0.63 to 0.73 with cellulose and from 0.61 to 0.68 with hemicellulose. The amount of urinary aromatic acids, mainly in the form of hippuric acid, considerably exceeded the potential contribution of any non-lignin component which might affect the excretion of aromatic acids. A considerable percentage (71-76) of the apparently digested lignin was not accounted for as soluble phenolic compounds in faeces or as aromatic acids in urine, and hence was apparently completely metabolized. Lignin is a key substrate which is extensively digested in goats fed on low-quality forage, with subsequent absorption of endproducts. This enhanced the availability of structural carbohydrates for fermentation and was associated with excretion of high-energy metabolites in the form of benzoic and hippuric acids.

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Abstract: Abstract The possibility of growing Pleurotus while utilizing cotton straw and a combination of cotton straw (50%) and wheat straw (50%) as substrates for the production of edible mushrooms was examined on a pilot-plant scale. It is possible to preserve cotton straw anaerobically, creating a �silage-like� material with a typical pH of 5·5. Following composting, the pH of preserved cotton straw increased to 8·78. Organic matter losses after fungal growth on composted cotton straw substrates were considerably lower than on standard substrates (90% wheat straw and 10% alfalfa hay). The yield of edible mushrooms was maximal on the 50% wheat straw-50% cotton straw substrate, and the interval between inoculation and first harvesting of the mushrooms was shorter on cotton straw-based substrates than on the standard substrate. The increase in teh ash content during the growing period was also lower in the cotton straw-based substrates than in the standard substrates. During the growth cycle, lignocellulose content of the substrates decreased and detergent-soluble content increased, indicating that the quality of the substrate as a feedstuff for ruminants had improved. Effect of CaO- OR NaOH-hydrogen peroxide treatments on ... Bioresource Technology

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Abstract: 1. Metabolism of tritiated water and 22sodium was studied in six beef cows under Mediterranean summer conditions in order to find whether the turnover of these tracers can be used to evaluate pasture intake. 2. The diet of the cows included ad libitum access to two components which were given separately in different troughs: one was poultry litter and the other was wheat straw, to simulate the dry pasture. 3. Voluntary daily dry matter intake (111 g/kg0.75) was unexpectedly high considering the low digestibility of the feed. 4. The assumptions of constant ratios of water intake to water turnover and of dry matter intake to water intake were confirmed. Consequently, dry matter intake was determined accurately from water turnover measurements. 5. Sodium intake was practically equal to sodium turnover and most of the sodium secreted in feces was of endogenous origin. 6. Pasture intake can be predicted from sodium turnover once the concentration in feed and water consumed is known.

Abstract: The amount of lignin in the cell walls of cotton straw (CS) and wheat straw (WS) was found to be the same, but the ratio between lignin and hemicellulose was considerably lower in CS than in WS. In CS the amount of soluble acid lignin was less than 1% of the total lignin, whereas in WS it was 20%. The amount of phenolics in concentrated sulphuric acid (72%) hydrolysates of the cell wall was reduced drastically in WS compared with the amount released by diluted (1 N) sulphuric acid; this may have been due to polymerisation of low-molecular-size lignin. The amount of alkali-soluble lignin in WS was 3-7 times greater than in CS. Following acid treatment the amount of alkali-soluble lignin was reduced from 20% of the total content to 5% in WS, and from 5% to 1% in CS. Enzymic hydrolysis was 49% higher in WS cell wall than in CS cell wall. In WS, acidic and alkali pretreatments followed by cellulase treatment increased glucose yield from cellulose by 260% and 280%, respectively. In CS, acidic pretreatment did not affect the glucose yield from cellulose, whereas alkali treatment increased it by 35%.

Abstract: Sheep fully exposed to Mediterranean summer conditions had a higher respiration rate and a higher body temperature than sheep with access to shade. Nevertheless, feed intake and water intake of non-sheltered animals was not different from that of sheltered ones and both maintained their body weight on medium quality hay. Apparent digestibility of organic matter was higher in the non-sheltered animals than in the sheltered ones. The mean retention time of undigested feed in the rumen and in the entire digestive tract was higher in the non-sheltered animals than in the sheltered ones. Water turnover rate was only slightly higher in the non-sheltered animals than in the sheltered ones. However, plasma volume and extracellular volume were significantly higher in non-sheltered than in sheltered animals. The volume of water in the alimentary tract was not different between the two groups.

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Abstract: The chemical composition of cotton straw (CS) was studied in order to evaluate its biotechnological potential. The main components in CS, as in other straws, are the cell wall carbohydrates. In comparison with cereal straws, CS contains considerably more cell solubles but the level of soluble carbohydrate is low, and the amounts of secondary metabolites high. The CS cell wall contains less hemicellulose and more pectic substance than wheat straw. It is possible to preserve CS under anaerobic conditions. However, an increase in level of lignin and a small loss of soluble organic compounds during aerobic fermentation was observed.

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Abstract: Intake of high quality roughage (alfalfa hay) by black Bedouin goats was lower than by Swiss Saanen goats. Bedouin goats have lower energy requirements and less tendency to accumulate solids. Apparent dry matter digestibility was higher in Bedouin than Saanen goats even when high quality hay was offered. It was more pronounced when a medium quality roughage (Rhodes grass mixed with alfalfa) was fed. Differences in apparent digestibility of dry matter were greater when a poor quality feed such as wheat straw was offered. Similar differences between the two breeds were noted in relation to the apparent digestibility of cell wall constituents (cellulose, hemicellulose, and lignin) and nitrogen. When medium quality roughage was fed, Bedouin goats apparently consumed enough energy to sustain both maintenance and production, whereas Saanen goats consumed only enough to maintain very low production. Bedouin goats maintained their body weight and solids on an energy intake up to 50% less than the estimated maintenance requirement of goats, whereas Saanen goats lost body weight and solids. It is suggested that reduction in metabolic rate helps desert ruminants cope with chronic energy shortage.

Abstract: Food consumption decreases with the lengthening of the period of dehydration in both breeds in a similar manner. However, in comparison, the Saanen goats reduced their dry matter intake and consequently their water intake much more than the Bedouin goats. Apparent digestibility of dry matter increased significantly in both breeds during dehydration, the response being larger in the Saanen goats. Bedouin goats are capable of maintaining during 3 days of dehydration a level of consumption which is well above their maintenance requirements while the Saanen goats consumed only the amount of feed which is needed to satisfy their maintenance requirements.

Abstract: Three lactating and three non-lactating black Bedouin goats were subjected to four days of water deprivation or to hemorrhage. Four days of water deprivation caused body wt losses of 32 and 23% and plasma volume losses of 30 and 34% in lactating and non-lactating goats respectively. Plasma osmolality increased 17 and 15% in lactating and non-lactating goats. Plasma arginine vasopressin concentration rose from about 5 pg/ml to a mean of 36 pg/ml. Plasma renin activity increased from about 0.7 ng/ml/hr to a mean of 3.45 ng/ml/hr in lactating and to 3.15 ng/ml/hr in non-lactating goats. At 4.5 hr post-rehydration plasma osmolality and plasma vasopressin concentration were back to normal in non-lactating, but still elevated in lactating goats. Plasma renin activity increased after rehydration. Rapid blood volume loss of 21-28% increased plasma vasopressin concentration to 16-35 pg/ml in non-lactating and to 70 or greater than 500 pg/ml in lactating goats. It is concluded that black Bedouin goats are well adapted to endure severe dehydration and rapid rehydration, but that they (especially lactating animals) react strongly to rapid volume depletion.

Abstract: Abstract 1. 1. The green toad (Bufo viridis) reaches in Israel the southern limit of its distribution and penetrates arid zones. Throughout the dry season (6�8 months) it stays out of the water and uses protective terrestrial shelters. 2. 2. In the present study green toads were tested in the laboratory following their prolonged exposure to terrestrial conditions in drying soil. 3. 3. After three months in the soil blood plasma concentration of the toads reached a maximum of 1400 mOsm/kg with an urea concentration of 900 mM. Intracellular urea concentration in the muscles of these toads amounted to only 500 mM. 4. 4. Linear correlations were demonstrated between plasma osmolality and plasma urea concentration and between plasma urea concentration and urea concentration in the muscle.

Abstract: Renal responses were compared between desert (black Bedouin) and non-desert (Swiss Saanen) goats fed Lucerne hay ad. lib., Lucerne hay restricted to 65% of the ad. lib. consumption and wheat straw. Reduced feeding in both breeds resulted in proportional reduction in glomerular filtration rate (GFR) and the amount of urea excreted with no change in the percentage of urea reabsorbed. In both breeds appreciably less urea was filtered at the glomerulus when a low-nitrogen diet was fed compared with a high nitrogen diet and the percentage of filtered urea reabsorbed increased from about 55 to about 90%. In both breeds the reduction in GFR is quantitatively more important than the increase in the percentage of filtered urea reabsorbed in regard to renal urea conservation. The results indicate no qualitative differences between desert and non-desert breeds of goat. The advantages of the Bedouin over the Saanen goats is related to the lower GFR values in the Bedouin goat and mainly their ability to reduce its GFR much more than the Saanen goats in response to lower nitrogen intake.

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Abstract: 1. 1. Black Bedouin goats (16�24 kg body wt) at 4�5 months post partum produce daily in the laboratory 50 g milk per kg body wt. Similar yields were recorded at mid-summer in goats herded in the desert where food is meagre, low in protein and water is scarce. 2. 2. Urine concentration in lactating goats was higher than in goats before gestation but urine urea concentration was only a third that in the non-lactating ones. The increase in urine volume in the lactating goats was less pronounced than the increase in drinking and water turnover rates or in food consumption. 3. 3. Daily renal reabsorption of urea in lactating goats amounted to 588 mmol compared to only 361 in non-lactating ones. Urine urea loss in lactating goats was 25% less than in the non-lactating ones. 4. 4. Urea entry rate in lactating goats was 65% higher than in non-lactating goats. 748.6 mmol urea were recycled daily in lactating goats compared to only 277 mmol in non-lactating ones. 5. 5. The role the kidney plays in economizing both water and nitrogen metabolism in goats lactating in the desert is assessed and discussed.

Abstract: Percentage net phosphorus availability (NPHA) and set phosphorus utilization (NPHU) of the phosphorus contained in a heat-sterilized poultry litter (PL) as compared to feed grade dicalcium phosphate (DCP) for lambs was assessed by the "slope" method. The method was based on the evaluation of the function of apparent phosphorus absorption (NPHA), or retention (NPHU), on phosphorus intake. Nitrogen retention was also evaluated. Plasma inorganic phosphorus concentration as a function of phosphorus intake was evaluated and compared to NPHA and NPHU. The percentage of NPHA was found to be 63.7 and 39, and that of NPHU was 63 and 38 for the phosphorus supplied by DCP and PL, respectively. Thus, the NPHA or NPHU for the phosphorus contained in PL is 60.9 and 60.3% of that of DCP, respectively. The slope ratio between the two phosphate supplements as observed for plasma inorganic phosphorus concentrations was similar to those found for NPHA and NPHU but the coefficient of variation was 5 times higher. Nitrogen digestibility was not affected by the level of phosphorus in the diets. Correlation between nitrogen retention and NPHA or NPHU was, however, significant (P less than 0.05). The slopes of dependence of N retention upon phosphorus intake were 2.81 and 1.6 (P less than 0.05) for DCP and PL treatments, respectively, and the ratio between the slopes was 0.57, close to the ratio of NPHU in PL to DCP-supplemented diets.

Abstract: Abstract 1. 1. Gross energy digestion and urea recycling were measured in Bedouin goats inhabiting extreme deserts in the Middle East and compared to Swiss Saanen goats. 2. 2. The apparent gross energy digestibility of alfalfa hay and wheat straw in the black Bedouin goat were 6% and 33% respectively higher than in the Swiss goat. 3. 3. When the amount of alfalfa hay fed was restricted to about 60�70% of the ad lib consumption, recycling of urea in the Bedouin goats was maintained at rates (0.44g·N-urea [kg·day]�1) similar to those recorded when alfalfa hay was fed ad lib. In the Swiss goats a 30% drop was recorded. 4. 4. When wheat straw was the only feed, the amount of urea recycled by the Bedouin goats (0.18 g·Nurea [kg·day]�1) was more than twice the amount recycled by the Swiss goats. 5. 5. Supplementing the wheat straw to provide both breeds with equal amounts of digestible energy and nitrogen intake resulted in an increase in the amount of urea recycled in both breeds. The Bedouin goat, however, still recycled twice as much urea (0.3 g·N-urea [kg·day]�1) as the amount recycled by the Swiss goats. 6. 6. It was concluded that under adverse nutritional conditions the Bedouin goat possesses high potentials to both meet its caloric demands as well as to economise its nitrogen metabolism and the two characteristics are complementary to each other.

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Abstract: We examined whether casein hydrolyzate treatment at dry off in combination with antibiotic improved bacterial cure and increased milk yield in subsequent lactations in comparison with treatment with antibiotic alone. The major bacterial isolates in samples collected prior to drying-off comprised coagulase-negative staphylococci, mostly as Staph. chromogenes. The cure rat of treatment with casein hydrolyzate was 73.8%, significantly higher than the 51.7% cure recorded when cows were treated only with antibiotic. Treatment with casein hydrolyzate significantly increased milk yield by 9% (above the 2% expected due to genetic selection) in the first lactation after the treatment and by 6.3% (above the 4% expected for 2 years due to genetic selection) in the second lactation after treatment. Thus, treatment with casein hydrolyzate at dry off was shown to be a viable mean to eliminate environmental bacterial infection during the dry period, and to improve milk yield.

Abstract: It has been shown recently that the main function of bovine milk catalase is oxidation of nitrite to nitrate in a hydrogen peroxide depended manner. The aim of the present study was to characterize the nitrosative stress induced by lipopolysaccharide challenge of the mammary gland and the role played by catalase in modulating the stress. The large increase in xanthine oxidase and lactoperoxidase activities and in the concentration of nitrate and nytrotyrosine upon lipopolysaccharide challenge reflects their role in the glandular innate immune system. The marked increase in catalse activity and the relatively small increase in nitrite concentration in comparison to the large increase in nitrate concentration reflect its protective role in preventing excessive nitrosative stress.

Abstract: Subclinical mastitis in dairy sheep and goats has major deleterious effects on both the yield and the quality of milk. Improved insight into the interaction between bacteria and the affected gland was achieved by comparing infected and uninfected glands in the same animal. Lower concentration of lactose in the infected glands was associated with higher whey and albumin concentrations. In both sheep and goats curd yields from the infected halves were Lower than those from the uninfected ones, although casein concentrations were almost equal in the two glands. It is Likely that modifications in the casein micelles, caused by bacterial activity, are more detrimental to curd formation than to casein formation; this is also indicated by the Longer clotting time of milk in the infected glands. Plasmin, the major proteolytic enzyme, in milk exists mostly as inactive plasminogen, and is activated by plasminogen-activator. Beta-casein is a natural substrate of plasmin, and a beta-casein-derived peptide down-regulates milk secretion. In goats, plasminogen activity was close to zero, possibly because of unusually high plasminogen-activator activity. The higher casein content, together with the higher plasmin activity, in sheep than in goats resulted in higher contents of casein degradation products, which include factors that down-regulate Lactose and milk secretion. The higher degradation of casein explains the higher Loss of curd and the lower milk yield in response to bacterial infection, in sheep than in goats.

Abstract: Accumulation of casein-derived peptides to critical concentration in milk stored in the mammary gland induces the process of mammary involution in the gland. The ability of casein hydrolyzates (CNH) to dry-off milk secretion in infected mammary quarters and cure microbial infection was evaluated. Lactating cows, infected by various common pathogens in one quarter and having an average somatic cell count (SCC) of 2,000,000 were treated. An infected quarter was infused with 10 ml of CNH (prepared under GMP conditions) three consecutive times, 24 h apart, after milking. Treatment accelerated and synchronized the natural involution process as reflected by rapid dry-off of milk secretion in 35 out of 37 cows within 3 days. Dramatic changes in the composition of mammary secretion: disappearance of Lactose and fat and accumulation of whey proteins with components of the innate immune system were observed. The bactericidal activity of mammary secretion of treated glands, which started within 8 h, persisted after the 3 day course of CNH treatments protocols. Immediate success resulting in SCC of Less than 400,000 in the three functional glands in post-treated cows was 85%. After parturition, 78% of the treated quarters were bacteria free. Thus, CNH appears as an effective too[ to improve milk hygiene in cows exposed to subclinical and chronic mastitis and to eliminate bacterial infection. The Latter properties of CNH treatment also suggest that it may be used as an effective non-antibiotic dry treatment for cows.

Abstract: The paper can be downloaded at: http://books.google.com/books?hl=en&lr=&id=qawmWu-oKh8C&oi=fnd&pg=PA221&dq=+%22silanikove%22&ots=u83OhVYAuP&sig=9mn5hJTmtdzJrbtqcoS60qo-lPM

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Abstract: Clinical mastitis although causing direct economic loss to farmers, does not affect the quality of the bulk milk and thereafter cheese, since those animals are milked separately. In contrast, milk from sub-clinically infected udders is milked into the bulk milk tank, thus having a direct influence on the milk quality for industrial uses. Comparing milk from sub-clinically glands infected by one of the udder pathogens: Staphylococcus aureus, Escherichia coli, Streptococcus dysgalactiae and Streptococcus chromogenes causing similar somatic cell counts and similar cell distribution resulted in significant differences in milk quality and curd yield. Clotting time in milk coming from infected glands was longer (1294 sec vs. 3663 sec) and curd firmness measured by Optigraph (A30) was lower (10.38 V vs. 2.26 V). No differences were found in total fat, portion and casein between the control and infected milk. Moreover, in the first two weeks of ripening, 2-3 times more whey drained from the cheese of the infected quarters, resulting in ~4% less curd. The strength of the cheese as determined by the TA XT2 Texture analyzer was significantly higher in the first 2 months and significantly lower at 4 months in the control cheese vs. cheese from the infected quarters. In parallel, size-fractionation of the milk�s proteose-peptone was achieved by FPLC Gel Filtration. Lyophilized fractions were added to fresh bacteria-free milk, which resulted in a significant negative effect of the lower MW fraction that increased clotting time by 3-5 times in infected milk. The reported results suggest that there is a direct influence of bacterial enzyme/s and/or the host immune system response to the various bacteria that cause sub-clinical mastitis, which has a detrimental effect on the quality and yield of cheese made from that milk, with no relation to the effect on the milk itself, i.e., increased somatic cell count and fat and casein content of the milk.

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Abstract: Forty-eight 50% Boer � Spanish doelings (4 mo of age, 20.9 ± 2.4kg) were randomly assigned to three treatments to test the effects ofpolyethylene glycol (PEG) supplementation of grazed sericea lespedezaand early post-weaning nutritive plane on subsequent growth. Treat-ments were: barn (B) where goats were kept in individual pens for the24-wk trial and fed free-choice a 70% concentrate diet (17% CP, 69%TDN); PEG (P); and control (C). In the first 6 wk (Phase 1), P andC doelings grazed .44-ha lespedeza paddocks supplemented with 88 g/dof concentrate with or without an additional 25 g/d PEG. In the sub-sequent 6 wk (Phase 2), C doelings resided in previously ungrazed 1-hapaddocks dominated by crabgrass, whereas P doelings grazed 1-ha les-pedeza paddocks supplemented with approximately 1.5% BW of the diet. In Phase 3, the final 12 wk, all doelings had ad libitum accessto the 70% concentrate diet in confinement. Body weights were deter-mined at 3-wk intervals and ADG was calculated by regression usinginitial BW as a covariate. Phase 1 ADG ranked (P < .05) B>P>C(157, 97, and 47 g/d; respectively, SE = 10.9). The ADG in Phase 2(B 70, P 55, and C 57 g/d; SE = 9.3), Phase 3 (B 80, P 85, and C 73g/d; SE = 7.6), and the whole trial (B 87, P 73, and C 56 g/d; SE =8.2) were similar among treatments (P > .05). In conclusion, PEG mayhave potential to improve ADG by goat kids grazing tannin-containingsericea lespedeza, although testing over a longer time frame is needed.Differences in ADG in the early portion of the grazing period did notelicit increased ADG later with feeding of a concentrate-based diet rel-ative to continuous concentrate consumption reflecting an absence ofcompensatory growth.Key Words: Goats, Polyethylene Glycol, Sericea Lespedeza

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Abstract: Symposium H: Interaction of osmotic and volume regulation Result list | previous < 3 of 9 > next

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