Evaluation of an enzyme-linked immunosorbent assay for detection of antibodies to bovine virus diarrhoea virus in milk

The present study shows that milk is an appropriate source for detection of seroreactors to bovine virus diarrhoea virus (BVDV). There was close agreement between antibody titres in serum and in skim milk, as determined by an indirect enzyme-linked immunosorbent assay. The antibody titres were usually lower in skim milk than in serum, but all seropositive cows (n = 84) were also skim milk-positive and all but one seronegative cow (n = 55) proved negative in skim milk. During lactation, the level of antibodies to BVDV in milk showed an inverse relationship to the amount of milk produced. However, there was a sufficient level of antibodies in milk throughout lactation to permit an adequate determination of BVDV antibody status in dairy cows. There was a mutual good agreement between milk antibody titre in the four mammary quarters, irrespective of milk cell count. Milk can be used to detect seroreactors to BVDV. Milk is preferable to blood in large-scale epidemiological studies, since the sampling procedure is much simpler.     

The relationships of birth weight, preweaning gain and postweaning gain with the bovine major histocompatibility system

A total of 739 cattle from nine breeds maintained at the Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, Nebraska were tested for 42 class I antigens of the bovine major histocompatibility system (BoLA). Each antigen appears to be the product of a distinct co-dominant allele of the BoLA-A locus. The number of antigens present in each breed ranged from a minimum of 10 in Hereford to a maximum of 21 in Charolais cattle. There were large differences among breeds in the frequencies of antigens. The effect of each antigen on birth weight, preweaning weight gain and postweaning weight gain was estimated in a gene substitution model. Each breed was analyzed separately. There were significant effects of some BoLA antigens on birth weight, preweaning weight gain and postweaning weight gain, which is consistent with previous reports showing associations between the major histocompatibility system and growth parameters in mice, rats and pigs. However, further research is necessary to confirm these findings and to determine the biological mechanisms underlying these associations.     

Vitamin deficiencies in cattle

Deficiencies of vitamins A, D, K, E and thiamin can cause severe limitations in beef production. In particular, vitamin A and E can be common causes of lost profit, secondary to limitations of reproductive and growth potential. Prolonged dry periods will reduce available A and E in pasture forage, as can ensiling and prolonged storage of harvested feedstuffs. Polioencephalomalacia is a thiamin responsive disorder, associated with high concentrate feeding and lush pastures. Antimetabolites, such as amprolium, will cause thiamine deficiency when fed in excess. Recent information has shown improved performance with supplemental beta carotene and niacin. The positive responses in reproductive performance, noted with cattle fed supplemental beta carotene, was independent of vitamin A. Supplementation of vitamins above National Research Council recommendations can be justified. However, proper evaluation of feed and animal status, and documentation of a response to supplementation is necessary before diagnosing deficiencies of specific nutrients.     

A novel HPLC method for glutathione-insulin transhydrogenase assay using fluorescence labeled insulin

The activity of rat liver glutathione-insulin transhydrogenase (GIT) was measured by HPLC. The degradation of fluorescein isothiocyanate-I (FITC-I)-labeled insulin is separated into several peaks, which are bound different amount of FITC-I. We selected mono-fluorescein-thiocarbamylated insulin to estimate the decrease of insulin content and it became possible to assay GIT activity. This novel method was time-saving and simple, and this system could utilize instead of previous method.     

改进芳草A系原种产卵性的试验

本试验采取母蛾延迟交配，拆对后冷藏、改变交配时间和产卵室保护温度等技术措施来探讨改善芳草A系原种产卵性的方法。结果表明，这些措施对产卵性能的改进有一定的效应，但由于性状间存在相关关系，对某一性状的促进效应往往同时也对另一产卵性状产生负向影响。     

N_(98s)×特青(亚种间杂交稻)抽穗后物质生产及分配特点研究初报

对N×特青示范田中试区与肥料试验田各处理小区稻株分析结果表明:抽穗后,亚种间杂交稻N×特青比常规稻特青干物质生产能力强,灌浆速度快;地上部各器官占植株干重比例,前者叶片比重大于茎,后者茎比重大于叶。亚种间杂交稻对肥料反应敏感,抽穗后,干物质累积,植株高度,每穗总粒数和粒重均随施肥量增加而增加,在高肥区有利于进一步提高产量,但增施氮肥后,灌浆速度明显滞后。     

北京鸭心迷走节前神经元的定位——HRP法研究

本研究用 HRP 逆行追踪法对北京鸭心脏各区的迷走节前神经元胞体进行定位。标记细胞呈双侧性,集中在疑核和迷走背核,以疑核占优势(占68.4%)。在疑核,标记细胞多位于闩的嘴侧(峰值在+1000～+1800 μm水平),为较大型(φ20～30 μm)、多突起的星形细胞。在迷走背核,标记细胞呈梭形(φ18～20μm),大部分位于闩嘴懊I平面(+100～+1800μm)的腹侧部。左心室主要接受疑核支配。发自迷走背核的心迷走神经节前纤维主要分布在冠状沟。     

Postovulatory Effect of Intravenous Administration of Lipopolysaccharide (Escherichia coli, O55:B5) on the Endocrine Status of Recently Ovulated Sows

The effects of lipopolysaccharide ( Escherichia coli , O55:B5), administered 18 h after ovulation in the second oestrus after weaning on the hormonal profiles in 14 Swedish cross-bred (Landrace × Yorkshire) multiparous sows were studied. The endotoxin group (E-group) sows were administered with 300 ng/kg of lipopolysaccharide (LPS) whereas the control group (C-group) sows were administered 5 ml of saline intravenously via an indwelling jugular cannula. Blood samples for hormonal analyses were collected from all sows until slaughter. In the E-group, progesterone, cortisol and prostaglandin F_2α metabolite levels increased significantly (p < 0.05) following LPS compared with the C-group. It can be concluded from this study that apart from elevating cortisol and prostaglandin F_2α metabolite, LPS also elevates progesterone levels.