Environmental pollution leads to increasing nitrate levels in dairy cattle's water supply. Possible repercussions regarding nitrate content in milk should therefore be considered. The results are presented of nitrate dosage in milk collected from cows provided with drinking water containing 0-180 mg/l nitrate. They show that drinking water has no significant effect on milk nitrate content which remains very low. ft is concluded that this product does not constitute a health risk to consumers.
Lambing in small ruminants is a time of high lentivirus expression; infected mononuclear phagocytes are frequent in colostrum and milk. We have studied mammary secretions in 5 multiparous ewes and shown that infected macrophages in milk are accompanied by an augmentation of leucocyte number. The lymphocyte CD8 subpopulation increased in size simultaneously with the onset of infected cell excretion. The udder infection by coagulase negative staphylococci did not modulate milk lymphocyte content Although infected cell excretion was restricted to one half of the udder, virus-specific lesions were found in both udder halves. Milk leukocytes changes are a marker of infected macrophage presence; they do not control lentivirus spread.
Pharmacokinetics and urinary excretion of sulfadiazine were determined in buffalo calves following single oral administration (1 50 mg/kg). Kinetic evaluation of plasma levels was performed using a 2-compartment model. The absorption half-life and elimination half-life were 3.41 +/-0.63 and 13.75 +/- 1.94 h, respectively. Based on this study, an optimal dosage regimen of sulfadiazine in buffalo calves would be 165 mg/kg, followed by 75 mg/kg at 12-h intervals. Sulfadiazine was mainly excreted in the urine as free amine, while the percentage of acetylated sulfadiazine was comparatively low.
In lymphoid tissue, the presence of high amounts of free proteins and immunoglobulins frequently leads to the observation of non-specific reactivities during immunohistochemical reactions. The types of anti-immunoglobulin sera utilized in these immunohistochemical reactions may be capable of identifying immunoglobulins secreted or harboured by the tissue cells under study, leading to non-specific marking. Incubation of these antisera with serum from the species in which the lymphoid tissue is studied neutralizes the non-specific reactivities connected
One hundred and three strains of Actinomyces pyogenes isolated from ruminants were examined for morphological, cultural and biochemical properties by standard tests and by the Api 50 CH and Api Coryne methods. No biotype could be demonstrated, but a few atypical non- or practically non-proteolytic strains were detected which should be differentiated from Arcanobacterium haemolyticum. Criteria for laboratory identification of A pyogenes were established: Gram stain; culture on blood agar; deep agar and Loeffler's medium; catalase, nitrate reduction, acid formation from xylose; Hugh and Leifson test. The Api Coryne system correctly identified only 58 of 103 A pyogenes cultures, which implies that it should be re-evaluated before use in veterinary diagnosis laboratories.
It has been over 50 years since vitamin E was originally described as a lipid-soluble dietary constituent required for normal reproduction in rats. Vitamin E is recognized as an essential vitamin required for all classes of animals functioning predominantly as an intracellular antioxidant in maintaining the integrity of biological cell membranes. Although a wealth of information has been gathered on clinical signs of vitamin E deficiency, establishing its requirements for animals has been exceedingly difficult because of interrelationships with other dietary constituents. Vitamin E requirements for animals cannot be defined in isolation. Requirements are influenced by the amount and type of fat (particularly with monogastrics) and degree of fat oxidation in the diet; the presence of antioxidants; dietary selenium (closely interrelated with vitamin E), iron, copper, and sulphur amino acids, as well as the physiological status of the animal. Other factors to be considered in assessing vitamin E needs of animals under commercial production conditions include: a) variability of vitamin E content in feedstuffs; b) poor stability of vitamin E during processing and storage of feeds; and c) management practices resulting in overstressed animals. Information on the function of or requirements for vitamin E in animals is very incomplete. Estimated dietary vitamin E requirements for most animal species are in the range of 10-40 IU/kg of diet. Of particular concern is the lack of vitamin E requirement information regarding young dairy and beef calves. Although good experimental evidence indicates a beneficial role of supplemental vitamin E above physiological levels on overall performance, enhanced immunocompetence and preservation of meat and milk products, levels of vitamin E required to produce these desired effects needs to be firmly established. Present estimated dietary requirements for vitamin E across species may need to be redefined as new information becomes available about the role this nutrient plays in growth, health and overall metabolism.
