Pyrrolizidine alkaloid poisoning of yaks (Bos grunniens) and confirmation by recovery of pyrrolic metabolites from formalin-fixed liver tissue.

Severe losses of yaks (Bos grunniens) were investigated in the most eastern region of Bhutan. The most serious disease was a fatal chronic skin disease with emaciation and anaemia. Post mortem examinations revealed major lesions in the liver, consisting of hepatic megalocytosis, bile duct proliferation, fibrosis and remodelling of the hepatic structure. There was also renal megalocytosis, ascites and mild to moderate icterus. Pyrrolizidine alkaloid poisoning was diagnosed and confirmed by demonstrating sulphur-bound pyrrolic metabolites of the alkaloids in preserved liver tissue. Skin lesions with hyaline parakeratosis were an important feature. Similar lesions were found in the mucosa of the oral cavity. No records could be found of such skin lesions in any other species or disease. Pyrrolizidine alkaloid poisoning seriously affects the livelihood of the local population which depends almost entirely on the yak. Various control measures are discussed. The key to be found is the identification of the toxic plants.     

Pyrrolizidine alkaloid poisoning of sheep in New South Wales

Pyrrolizidine alkaloid poisoning of sheep in New South Wales was reviewed, based on the records of the New South Wales Department of Agriculture's Regional Veterinary Laboratories. The plant species causing significant mortalities were Echium plantagineum and Heliotropium europaeum. The syndrome of hepatogenous chronic copper poisoning was more frequently diagnosed than primary pyrrolizidine alkaloid poisoning, particularly when grazing E. plantagineum. The data indicated that adult crossbred ewes were the most commonly affected class of sheep.     

Comparison of hepatic in vitro metabolism of the pyrrolizidine alkaloid senecionine in sheep and cattle

OBJECTIVE: To compare hepatic metabolism of pyrrolizidine alkaloids (PAs) between sheep and cattle and elucidate the protective mechanism of sheep. SAMPLE POPULATION: Liver microsomes and cytosol from 8 sheep and 8 cattle. PROCEDURE: The PA senecionine, senecionine N-oxide (nontoxic metabolite) and 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP; toxic metabolite) were measured in microsomal incubations. The kcat (turnover number) was determined for DHP and N-oxide formation. Chemical and immunochemical inhibitors were used to assess the role of cytochrome P450s, flavin-containing monooxygenases (FMOs), and carboxylesterases in senecionine metabolism. The CYP3A, CYP2B, and FMO concentrations and activities were determined, in addition to the role of glutathione (GSH) in senecionine metabolism. RESULTS: DHP concentration did not differ between species. Sheep formed more N-oxide, had higher N-oxide kcat, and metabolized senecionine faster than cattle. The P450 concentrations and isoforms had a large influence on DHP formation, whereas FMOs had a large influence on N-oxide formation. In cattle, CYP3A played a larger role in DHP formation than in sheep. FMO activity was greater in sheep than in cattle. Addition of GSH to in vitro microsomal incubations decreased DHP formation; addition of cytosol decreased N-oxide formation. CONCLUSIONS AND CLINICAL RELEVANCE: Hepatic metabolism differences alone do not account for the variation in susceptibility seen between these species. Rather, increased ruminal metabolism in sheep appears to be an important protective mechanism, with hepatic enzymes providing a secondary means to degrade any PAs that are absorbed from the rumen.     

The uniqueness and superiority of energy utilization in yaks compared with cattle in the highlands:A review

Yaks living on the Qinghai-Tibetan Plateau for a long time have evolved a series of mechanisms to adapt to the unique geographical environment and climate characteristics of the plateau. Compared with other ruminants, yaks have higher energy utilization and metabolic efficiency. This paper presents possible mechanisms responsible for the efficient energy utilization, absorption and metabolism resulting from the unique evolutionary process of yaks. It is hoped that the information discussed in th...     

Effects in sheep of high dietary levels of vitamin D3 as measured by circulating concentrations of some vitamin D metabolites and skeletal examination

Housed non-pregnant ewes were given diets supplemented with five, 10, 20, 40 and 80 times the Agricultural Research Council's recommended requirement for vitamin D for 16 weeks. The effects on vitamin D status were assessed by measuring 25-hydroxylated vitamin D metabolites (25-OHD) in plasma at intervals. After 16 weeks, animals on the lowest and two highest vitamin D intakes were killed for histological examination of selected soft tissues and bones. Circulating concentrations of 25-OHD increased with intake and time during the experiment. However the increases were not proportional to intake and only when intakes exceeded 20 times the recommended requirement were concentrations greater than those seen in summer in grazing sheep. There was some evidence for the production of an additional vitamin D metabolite in animals on high vitamin D intakes. No abnormalities were detected in any of the tissues examined histologically.     

补饲、隔离断乳及同期发情处理对当年产犊母牦牛人工授精受胎效果的研究

通过采用补饲、隔离断奶及同期发情处理方法,考察对母牦牛发情率、人工授精受胎率及产犊率等繁殖性能的影响。研究结果表明,补饲+断乳组初产母牦牛和经产母牦牛与隔离断乳组及对照组初产母牦牛和经产母牦牛的诱导发情率、受胎率产犊率相比,差异显著(P0.05);补饲组、隔离断乳组与对照组初产母牦牛和经产母牦牛的诱导发情率、受胎率产犊率相比,差异显著(P0.05);断乳+同期发情组初产母牦牛与补饲+断乳+同期发情组初产母牦牛的诱导发情率、受胎率产犊率相比,差异显著(P0.05);断乳+同期发情组经产母牦牛与补饲+断乳+同期发情组及补饲+同期发情组经产母牦牛的诱导发情率、受胎率产犊率相比,差异显著(P0.05)。研究表明,采用补饲、隔离断乳及同期发情处理相结合的综合措施,能显著提高当年产犊母牦牛的发情率、人工授精受胎率及产犊率。     

Immunohistochemical demonstration of canine distemper virus antigen as an aid in the diagnosis of canine distemper encephalomyelitis

Brain tissue from 33 dogs with non-suppurative encephalitis was examined for evidence of canine distemper virus (CDV) encephalitis. Sections were examined for lesions, inclusion bodies, syncytial cells and CDV antigen using a double bridge unlabelled antibody enzyme technique. Histopathological lesions considered to be typical of granulomatous meningoencephalomyelitis were found in seven dogs. They all lacked inclusion bodies, syncytial cells and CDV antigen. The remaining 26 dogs all had histopathological lesions typical of CDV encephalitis. Inclusion bodies were found in 24 dogs, four of which also had syncytial cells and CDV antigen was detected immunocytochemically in 25. One dog had no inclusion bodies or syncytial cells and was immunohistochemically negative. Syncytial cells have been found to be of limited diagnostic value for the diagnosis of CDV encephalitis. While inclusion bodies proved to be a good diagnostic criterion for the confirmation of CDV infection, the immunohistochemical demonstration of CDV antigen proved to be superior. CDV antigen was more prevalent than inclusion bodies in tissue sections and much more easily detectable.     

Effects of increasing days of exposure to prepartum diets on the concentration of certain blood metabolites in dairy cows

Objective To evaluate the effect of the number of days exposure to a prepartum transition diet on mineral, energy and protein metabolism in dairy cows. Design A prospective cohort study. Procedures The prepartum transition diet consisted of ryegrass pasture, cereal hay, grain, grain by-product, protein meals, BioChlor®, rumen modifiers, minerals and vitamins and contained 13.9% crude protein, 10.0 MJ metabolisable energy/kg and a dietary cation anion difference of −35 meq/kg dry matter. Forty cows were bled bi-weekly from their introduction to the prepartum transition diet until day 35 of lactation. Blood samples were submitted for estimation of a range of metabolites. Cubic smoothed splines were fitted to scatterplots of metabolite concentration as a function of day relative to calving and the area under the curve (AUC) was calculated. Linear regression modelling determined the effect of days exposed, age, body condition score (BSC) and calving day on AUC. Results The prepartum AUC of blood phosphorus and beta-hydroxybutyrate increased and the AUC of blood calcium and cholesterol decreased with increasing days exposed to the diet. The postpartum AUC of beta-hydroxybutyrate and non-esterified fatty acids decreased with increasing days exposed but increased with days exposed × age and days exposed × BCS, respectively. The AUC of other metabolites did not vary significantly with number of days exposed. Conclusions Increasing exposure to the prepartum diet significantly altered the AUC of blood metabolites associated with mineral, energy and protein metabolism in ways consistent with improvements in production and reproduction previously reported and the result suggests links between energy, protein and skeletal metabolism.     

The migration test on circulating bovine leukocytes and its possible application in the diagnosis of Johne's disease

The leukocyte migration test for in vitro studies of delayed type hypersensitivity has recently been reviewed (Søborg & Ben-dixen 1967; Bendixen & Søborg 1969). Søborg & Bendixen applied the test to circulating leukocytes in man and thereby widely increased the potentialities of this test. They obtained high leukocyte yields with only moderate erythrocyte admixture by harvesting the supernatant plasma after sedimentation of the erythrocytes for 60 min. at 37°C in the normal gravitational field (1 × g)- Their procedure was unsuitable for the present investigation because bovine erythrocytes sediment so slowly. Sedimentation after clumping at the interphase of aqueous solutions of polymers, dextran and methylcellulose, in combination with metrizoic acid (Böyum 1968) was tried without success because the vast majority of the leukocytes sedimented together with the erythrocytes. Separation of leukocytes from erythrocytes could not be achieved by differential centrifugation.