丁酸对肠道健康的影响

尽管我们很清楚丁酸在动物营养中的功能,但是在不同的胃肠道区段,丁酸对动物的消化功能、肠道微生物菌群组成和免疫应答反应的影响也不相同。     

放牧家畜模拟践踏器研究

放牧家畜践踏在草地退化和健康维护中起主导作用而具有重要的研究意义。结合放牧家畜放牧行为和踏压作用力分析,采用气泵与践踏器直接连接的设计,研制了"手持式气动放牧家畜模拟践踏器"。"手持式气动放牧家畜模拟践踏器"是一种精确模拟放牧家畜的践踏作业的手提便携式专业工具。通过压缩气体进入汽缸,推动活塞上下运动,模拟放牧家畜的践踏作用,模具平台前装有活动关节可同时模拟放牧家畜践踏的"摩擦削切作用",由于汽缸工作压力大小可调节,践踏次数可计数,从而实现对牛、马、羊等放牧家畜的践踏可调节、可计量的目的。该机设计结构紧凑、体积小、重量轻、机动性强、手提便携、性价比高,特别适用于小尺度研究各种放牧家畜践踏对任意类型草地的作用。     

饲养管理对种鸡生产性能的影响

近年来,为了追求鸡肉产量,尤其是高效的饲料转化率、较高的胴体产量和增重等指标,鸡遗传性状的选择已聚焦于高产鸡种,但这些性状与可孵化种蛋数性状呈负相关。这需要在饲养中重点关注鸡群的均匀度,以使同栏鸡群能同时出栏。     

Impact of internal parasites on beef cattle

Internal parasitism is a pervasive constant that reduces returns in beef cattle production. Parasitism may influence production sufficiently so that data derived investigating performance response will be erroneous. The interaction of internal parasites of cattle with other facets of their lives makes it imperative that more parasite research be done on cattle to consider their impact. Results of trials designed to determine forage production at various stocking densities may not reflect the nutritive value of the forage, but instead the severity of parasite exposure. Relative resistance or susceptibility to certain parasites vary with the breed of livestock and the species of parasite. Extensive work to evaluate the ability of various breeds and sires to influence parasitic numbers has been conducted in sheep but not in cattle. Some parasite trials have ignored the effects of nutrition on the establishment and retention of parasites. This becomes especially important where multiple parasite exposure may occur. Susceptible cattle, even on an optimal diet, will become parasitized, but if reexposed to the same species of parasite, cattle on an optimal diet may be able to resist reinfection, whereas those on deficient diets will not.     

动物性食品中兽药残留对人体健康的影响

近年来,随着生活水平的不断提高,食品的安全问题越来越受到人们的重视。兽药在保障动物健康、提高畜禽生产力、改善畜产品品质中起到了重要的作用,但随之也产生诸多负面影响,如畜产品中兽药残留问题。目前,兽药残留问题已引起社会的广泛关注。本文就兽药残留的现状、对人体健康的影响及控制措施等进行阐述。     

“诱惑”的魅力与毒刺——从证据法角度浅析诱惑侦查

诱惑侦查作为一种实效性极强的侦查方式日益受到侦查实践部门的青睐。诱惑侦查带有一定程度的欺骗性,与刑事追诉中的基本价值追求相矛盾,备受争议。各国在放松对诱惑侦查禁止性规定的同时,又严格加以限制,力图充分利用这一可能严重侵害公民合法权益的侦查手段,平衡价值上的冲突。诱惑侦查所获证据之效力应坚持有限可采性,侦查人员实施的犯罪行为之刑事责任的证据应坚持有限豁免性。     

环境因素对养鸡生产的综合影响

在养鸡生产中，许多养鸡专业户都知道环境因素对鸡生产性能的影响，所以在避免环境因素对鸡的生产性能影响方面采取了各种措施，避免了许多损失。但是笔者在社会生产服务中仍然发现许多问题：在正常饲养情况下，产蛋鸡产蛋率不能升到高峰或开产推迟，肉用鸡料肉比比较高、出栏推迟等现象时有发生。分析其原因：都是饲养管理中只考虑了单一环境条件的影响，而没有考虑环境因素的综合影响。1 环境因素对生产性能的影响1.1 温度的影响许多养鸡户只考虑按品种的饲养要求饲喂符合饲养标准的日粮，往往不考虑季节性温度的变化，不知及时调整配方，…     

环境条件对啮齿动物种群的影响

啮齿动物的种群调节理论一直是业内研究者争论的重点,在自然界中,种群数量变动的影响因素以及它们的相互作用极为复杂,越来越多的研究认为外在因素对种群变化起到关键作用。在查阅大量文献的基础上,对小型啮齿动物种群数量造成波动的外在因素进行了综述,概述了食物、降雨、降雪以及温度对不同种类啮齿动物种群的影响。     

Impact of dominance effects on sow longevity

The purpose of the current study was to estimate variance components, especially dominance genetic variation, for overall leg action, length of productive life and sow stayability until third and fifth parity in the Finnish pig populations. The variance components were estimated in two purebred [Landrace (LR), n = 23 602 and Large White (LW), n =22 984] and crossbred (LR × LW, n = 17 440) data sets. Five different analyses were carried out for all the traits to compare the effect of sows’ inbreeding, common litter environment and parental dominance in the statistical model when determining the genetic correlations of the traits for the two purebred and crossbred populations. Estimated heritabilities for the traits ranged from 0.04 to 0.06. The estimates for the proportion of dominance variance of phenotypic variance (d²) varied between 0.01 and 0.17, and was highest in the crossbred dataset. The genetic correlations of the same traits in purebred and crossbred were all high (>0.75). Based on current results, the effect of dominance should be accounted for in the breeding value estimation of sow longevity, especially when data from crossbred animals are included in the analyses. Because dominance genetic variation for sow longevity exists that variation should be utilized through planned matings in producing sows for commercial production.     

添加剂烟酸铬对家畜的影响

近年来,随着我国经济和饲料工业的迅速发展,各类饲料添加剂的使用也日益增加．特别是在提高饲料营养功能和保证饲料质量等方面．各种饲料添加剂越来越受到了人们的重视。烟酸铬作为一种饲料添加剂．具有提高家畜生长、生产和免疫性能．增强免疫能力．改善胴体品质,提高母畜繁殖性能,增加奶牛产奶量．缓解应激反应等功效：也是抗生素的潜在替代物。     

Impact of BSE on Livestock Production System

A total of 240 unvaccinated day-old broiler chicks, which had been found to be negative for antibodies against FAV-4, were divided into four groups of 60 chicks each. Group A was fed aflatoxin at 1 ppm from 7 days to 7 weeks of age. Group V was infected intra-abdominally at 14 days of age with 0.2 ml of FAV-4, having a titre of 10^5.5 TCID₅₀ per 0.2 ml. The combined group AV was given the aflatoxin and infected with FAV-4. The fourth group C served as the control. More pronounced clinical signs, a higher mortality rate (56.7%), and reductions in body weight gain and in the organ to body weight ratios of the bursa and spleen were recorded in group AV. A significant (p<0.01) reduction in the HI antibody titre following vaccination against Newcastle disease, and of skin thickness in the delayed hypersensitivity test following sensitization with DNCB, indicated an additive immunosuppressive effect from aflatoxin and FAV-4 on the humoral and cell-mediated immune responses in group AV compared to groups A and V. Microscopically, marked depletion and degeneration of lymphocytes in the thymus, bursa, spleen and caecal tonsils were observed in group AV up to 5 weeks PI.     

Impact of BSE on livestock production system

The small number of BSE cases diagnosed in Italy from January 2001 to 12 September 2001 (a total of 28, one every 9000 head) does not allow for a statistical analysis of the relationship between this disease and the livestock systems. However, some indications can be noted: (a) only dairy cattle, which represent three-quarters of the cattle raised in Italy, are involved; (b) 58% of the cases belong to medium-large farms that breed 27% of all head; (c) 13 out of 28 cases are 5-year-old animals and 26 out of 28 are between 5 and 7 years of age; (d) 15 of 28 cases come from Lombardia, where 27% of Italian dairy cattle are raised. The following factors may have affected the livestock system: (1) trends of beef meat consumption; (2) changes in livestock management; (3) changes in animal feeding; (4) possible effects on selection. A strong decline in beef meat consumption (4 kg/year) has been observed in the UK and other European countries since 1996 (the year of the discovery of the relationship between BSE and nvCJD). In Italy, from January 2001 the consumption of beef meat has declined as well as slaughter: a drop of 31% in the total slaughtered head in the period January-February, a drop of 14% in January-May. A fall in the price of calves has promoted, in some dairy farms, the start of the production of light beef less than one year old (advantages in the marketing of meat favour this initiative), a phenomenon which is not yet well established. Traceability and certification of meat have improved, thanks to breeders' associations and interprofessional agreements. The breeders associations have also started insurance initiatives against BSE risks. In Italy the employment of plant protein meals would increase the total feedstuff consumption by about 7%. Direct effects of BSE could slow down the genetic progress (GP) of cattle populations within breed and country. Indirect effects on GP may also happen as a consequence of an increase in the replacement rate (rr). This increase in rr reduced the generation interval and will therefore proportionally increase GP. Some important questions for the livestock production system are: Does the vertical transmission of BSE exist? Is there a genetic basis favouring the disease and is it inheritable? Are in vivo diagnostic tests possible? Are vaccination schemes against BSE possible and useful or is it better to pursue eradication?