Association between bovine-leukosis virus seroprevalence and herd-level productivity on US dairy farms

Bovine-leukosis virus (BLV; also termed ‘bovine-leukemia virus’) is a retrovirus that primarily affects lymphoid tissue of dairy and beef cattle. Our objective was to investigate the association between BLV infection and annual value of production (AVP) on dairy herds within the United States, as part of the USDA National Animal Health Monitoring System’s 1996 dairy study. 1006 herds (in 20 states) with at least 30 dairy cows were interviewed during 1996. The agar-gel immunodiffusion test was used to detect serum antibodies to BLV. 10–40 cows from each herd were tested and each tested cow was classified as negative or positive based on results of a single test.

A multivariable regression model was used with the 976 herds with complete data for analysis. When compared to herds with no test-positive cows, herds with test-positive cows produced 218 kg per cow (i.e. 3%) less milk. The average reduction in AVP was $ 59 per cow for test-positive herds relative to test-negative herds. For the dairy industry as a whole, BLV seropositivity was associated with loss to producers of $ 285 million and $ 240 million for consumers. Most of this $ 525 million industry loss was due to reduced milk production in test-positive herds.     

The stress response to environmental change in captive cheetahs (Acinonyx jubatus).

The captive North American cheetah (Acinonyx jubatus) population is not self-sustaining because of high prevalences of unusual diseases and poor reproductive success. Cheetahs are commonly moved between zoos for breeding purposes to maintain genetic diversity within the captive population, and movement may exacerbate infertility and disease. Fecal corticoids were analyzed by radioimmunoassay to measure the stress response of cheetahs to movement between facilities. Fecal samples were collected from 15 cheetahs for 14 days before movement and for at least 30 days after movement. For each cheetah, premovement fecal corticoid concentrations were used to determine baseline and then compared with trends in postmovement concentrations. In general, postmovement corticoid concentrations either increased (n = 8), did not change (n = 2), or decreased (n = 5). Although individual animal differences occurred, corticoid concentrations increased for most animals moved on-exhibit and decreased in animals moved off-exhibit. Animals moving on-exhibit had an 18-times greater risk of having corticoids elevated more than two standard deviations above baseline for 30 days after movement compared with animals that moved off-exhibit. In addition, greater day-to-day variation in corticoids occurred in animals moved on-exhibit. In general, animals with initially low baseline corticoid concentrations had a greater postmovement corticoid response than cheetahs with initially high baseline levels. These results indicate that some cheetahs have a prolonged stress response when moved between facilities, and the magnitude and character of this response is influenced by the exhibit environment.     

Pathogenesis of BSE

Before the emergence of bovine spongiform encephalopathy (BSE) and recognition of its zoonotic potential, the major example of the transmissible spongiform encephalopathies (TSEs) of animals was scrapie of sheep. But there is no evidence that scrapie transmits naturally to any species other than sheep and goats. The pathogenesis of scrapie has been studied most in experimental laboratory rodent species. In most experimental models of scrapie, after peripheral non-neural routes of infection, replication of the agent can first be detected in lymphoreticular system (LRS) tissue. When the route of introduction of agent into the body is localized, initial involvement will be in LRS tissue draining the infection site. Thereafter, there is a striking amplification of the agent in the LRS and spread by lymphatic/haematogenous routes, giving widespread dissemination in the LRS. This precedes replication in the CNS, but is not the means by which infection reaches the CNS. There is now substantial evidence from experimental models of scrapie that involvement of the CNS is by peripheral nervous system (PNS) pathways. In some models employing oral exposure the earliest localized LRS replication is in the gut-associated lymphoid tissue (GALT) and autonomic PNS routing to the CNS has been implicated. However, the relative importance of different routes of spread of TSEs within the body is determined by a number of host- and agent-dependent factors and, therefore, generalizations from an experimental model to a natural disease across a species barrier may not be appropriate. With the occurrence of BSE and recognition of its food-borne route of transmission via meat and bone meal, has come greater awareness of the probable importance of the oral route of infection in ruminant species affected by TSEs. In consequence, studies have increasingly focused on the natural host species to examine pathogenetic events.     

不同植物油对奶牛瘤胃液、血浆中脂肪酸及乳脂中共轭亚油酸组成的影响

为改善牛奶脂肪酸构成,提高乳脂中CLA含量,研究瘤胃液、血浆和乳脂中脂肪酸的代谢规律,探寻提高乳品质的合适途径,本试验以3头装有永久性瘤胃瘘管的经产荷斯坦奶牛为试验动物,采用3×3拉丁方设计,研究向日粮中添加不同植物油(即葵花油、亚麻油、菜籽油,3种日粮的粗脂肪含量基本相同)对奶牛瘤胃液、血浆中脂肪酸及乳脂中CLA的影响。结果表明:(1)日粮中添加3种不同植物油,葵花油组、亚麻油组乳脂中的CLA比例均显著高于菜籽油组(P<0.05),且以葵花油组最高;乳脂中PUFA的比例则是亚麻油组显著高于菜籽油组(P<0.05);(2)3组间血浆中C14∶0、C16∶0、C18∶0的比例差异不显著(P>0.05),菜籽油组C18∶1的比例显著高于亚麻油组和葵花油组(P<0.05),而后两组差异不显著(P>0.05),亚麻油组和葵花油组t11-C18∶1的比例与菜籽油组间差异均达到显著水平(P<0.05),亚麻油组和菜籽油组中C18∶2的比例差异显著(P<0.05);(3)采食添加不同植物油日粮后,瘤胃液中各种脂肪酸动态变化的平均值差异不显著(P>0.05)。总的趋势是随着时间的延长,饱和脂肪酸含量逐渐增加,而不饱和脂肪酸含量逐渐减少。瘤胃液中CLA的比例不同时间点均较低。由本研究可知,在优化奶牛乳脂肪酸构成提高CLA含量方面,以葵花油效果最好。     

Spongiform encephalopathy in an arabian oryx (Oryx leucoryx) and a greater kudu (Tragelaphus strepsiceros)

Clinical, pathological and epidemiological details of scrapie-like encephalopathies are described in an arabian oryx and a greater kudu. Clinical signs included ataxia and loss of condition with a short, progressive clinical course (22 and three days, respectively). Histopathological examination of the brains revealed spongiform encephalopathy characteristic of that observed in scrapie and bovine spongiform encephalopathy (BSE). It seems probable that these cases have a common aetiology with BSE. Scrapie-like spongiform encephalopathies have now been described in five species of exotic artiodactyls in Britain indicating a, hitherto inapparent, wider range of ruminant species as natural hosts for these diseases.     

Cardiac troponins

Objective: To review the use of cardiac troponins as biomarkers for myocardial injury in human and veterinary medicine. Data sources: Data sources included scientific reviews and original research publications. Human data synthesis: Cardiac troponins have been extensively studied in human medicine. Finding an elevated cardiac troponin level carries important diagnostic and prognostic information for humans with cardiovascular disease. Troponin assays are used primarily to diagnose acute myocardial infarction in patients with ischemic symptoms such as chest pain. However, elevated blood levels may be found with any cause of myocardial injury. Veterinary data synthesis: Several studies have shown that cardiac troponins are sensitive and specific for myocardial damage in veterinary patients and may have utility in diagnosis and prognosis for certain disease states. Human assays may be used in most animals due to significant homology in the troponin proteins between species. Conclusions: Cardiac troponins are sensitive and specific markers of myocardial injury although they do not give any information regarding the mechanism of injury. They have redefined how acute myocardial infarction is diagnosed in humans. Their use in the clinical management of veterinary patients is limited at this time. Further prospective studies are warranted.     

欧拉羊在甘南半农半牧区与山谷型藏羊的适应性对比

从甘南州玛曲县河曲马场引进欧拉羊种公羊30只,投放到卓尼县的半农办牧区进行放牧,观察欧拉羊的行为表现、生长发育、生理生化指标、繁殖性能、发病与死亡情况,结果各项指标正常,适应性良好,充分发挥了种公羊的生产性能,且具有杂交改良山谷型藏羊的优势,引种获得成功。     

The survival of platypus in captivity: a reappraisal with recommendations for veterinary management and future research

SUMMARY: Data are presented on the duration of survival of platypus held in the collections of the 5 Australian zoos displaying the species over the period 1987–1991. Of 10 living platypus, five had survived for 7 or more years. Similarly, of 10 captive animals that died during the period, six had survived for 6 or more years. Five purpose-caught animals were integrated into captive collections over the period; all of these were alive at the end of 1991. The high survival of captive platypus documented in this study contrasts with the conclusion of Whittington (1991) that the duration of survival of platypus in captivity is generally short. This primarily reflects differences in the nature of the two sets of data: Whittington's analysis was based on incomplete records dating back to 1934, and also categorised as managed in captivity those wild platypus that died at zoos while under veterinary care. A series of recommendations on current captive management issues includes the need for improved veterinary knowledge of platypus.