影响高产奶牛繁殖性能的营养因素

本文从奶牛泌乳、采食及体重变化入手,简要论述了饲粮蛋白质和能量水平对奶牛繁殖性能的影响,探索高产奶牛繁殖力较低的原因。奶牛场追求高产奶量,多会采取高比例精料、高蛋白水平的饲粮,从而造成过量氮化物对奶牛繁殖性能的毒害。产后泌乳量的快速上升和饲料干物质采食量的不足足导致了能量负平衡、体况评分下降过大、卵泡发育迟缓、产后发情晚、配种受胎率低、产犊间隔长等一系列问题。     

影响牛卵母细胞体外发育能力的因素

本文重点从三个方面探讨了影响卵母细胞成熟发育能力的制约因素：（1）通过分析卵母细胞核成熟和胞质成熟的过程及成熟时各细胞器的状态，指出在体外培养系统中卵母细胞的核成熟，并不代表胞质的成熟，推迟卵母细胞减数分裂的恢复能够有效促使胞质成熟；（2）针对母牛卵巢的功能结构和形态变化，卵泡发育程度及母牛发情周期的不同阶段等有关内容的实验材料，分析了卵泡发育过程中的几种关键因素对卵母细胞发育能力的影响，为了获得较多具有发育潜力的卵母细胞，提出了采集母牛卵巢的适宜情期阶段；（3）根据卵母细胞发育的不同的阶段，提出改善培养体系能提高卵母细胞的发育力。     

Long‐term Cultivation of Bovine Hoof Cells in a Novel Perfusion Chamber System

The aim of this study was to establish a co‐culture of bovine hoof keratinocytes and fibroblasts in different types of perfusion chambers under defined conditions. The perfusion chamber PCS3c (Oligene, Berlin) was used to culture dermal fibroblasts and epidermal keratinocytes separated by a Millicell^® Insert (Millipore, Schwalbach). In addition novel perfusion chambers developed by Dirk Hoffmann were used in combination with S & S membrane filters (Schleicher & Schuell, Dassel). First, fibroblasts were seeded onto one side of the insert/membrane and allowed to grow for 4 days. Subsequently keratinocytes were seeded onto the other side and allowed to adhere for one day. Then the chambers were connected to the tubing system with an attached 8‐channel pump and a gas permeable media bag. We worked with different media and flow rates ranging from 0.035 ml/min to 0.35 ml/min. The system was run for up to 20 days. After a few days in culture the cells had grown to confluence. Then keratinocytes began to differentiate and built up stratified colonies. Within these colonies the cells showed the characteristic morphology of a stratified squamous epithelium. The use of perfusion chambers allows three‐dimensional cultures to grow and survive for weeks, because of an unlimited medium supply and gas exchange. Additional, perfusion chamber systems enable the co‐cultivation of fibroblasts and keratinocytes separated by membranes, which permit the exchange of molecules like growth factors. Furthermore, it is possible to perfuse the two different parts of the perfusion chamber with various and even different types of media. This provides the opportunity to add a growth factor to the medium for only one cell type and to study the effect of this factor to the other cell type. This work was supported by the European Communities under the Lamecow project QLK5‐CT‐2002‐00969.The authors are solely responsible and the work does not necessarily represent the opinion of the European Communities.     

营养对基因表达的调控(上)

综述了营养对基因表达的调控方式及途径,并具体探讨了碳水化合物、脂肪酸、胆固醇、蛋白质、氨基酸、维生素、金属元素等营养素对基因表达的调控作用.作为外部因子,营养物质与基因表达之间存在着广泛的互作.营养素不但可作为代谢过程的底物、辅酶或辅助因子.而且它们可对许多编码蛋白质、酶、载体、受体和结构物质基因的表达进行调控.养分种类和摄入量可通过对基因的转录、mRNA的加工、翻译及定位来影响基因的表达及蛋白质合成,进而调控代谢过程,控制营养需要和疾病的发生.     

营养对基因表达的调控(下)

综述了营养对基因表达的调控方式及途径,并具体探讨了碳水化合物、脂肪酸、胆固醇、蛋白质、氨基酸、维生素、金属元素等营养素对基因表达的调控作用.作为外部因子,营养物质与基因表达之间存在着广泛的互作.营养素不但可作为代谢过程的底物、辅酶或辅助因子.而且它们可对许多编码蛋白质、酶、载体、受体和结构物质基因的表达进行调控.养分种类和摄入量可通过对基因的转录、mRNA的加工、翻译及定位来影响基因的表达及蛋白质合成,进而调控代谢过程,控制营养需要和疾病的发生.     

引起种公猪繁殖障碍的营养因素研究

适量的营养水平是提高公猪健康水平和繁殖性能的重要因素,营养水平过低或过高,均可导致公猪健康紊乱和生殖性能减退。作者对引起种公猪繁殖障碍的营养因素进行了综述。     

Leukotrienes are Auto‐/Paracrine Factors in the Bovine Corpus Luteum: An In Vitro Study

The aim of this study was to determine leukotrienes (LTs) functions in the bovine corpus luteum (BCL) during the oestrous cycle. In steroidogenic CL cells we examined the effect of luteotropic [LH, prostaglandin E₂ (PGE₂)] and luteolytic (PGF_2α, cytokines) factors on: the levels of LTB₄ and C₄, the expression of 5‐lipoxygenase (LO), LT receptors type I (LTR‐I) and LTR‐II, and the effects of LTB₄ and C₄ stimulations on the levels of progesterone (P4), PGE₂, F_2α and nitric oxide (NO) metabolites. Both luteolytic and luteotropic factors stimulated 5‐LO expression on days 2–4 and 17–19 of the cycle. Leukotriene receptors type I expression increased after PGE₂ and tumour necrosis factor α with interferon γ (TNF/IFN) stimulation on days 2–4 of the cycle. Leukotriene receptor type II expression increased after PGE_2α and TNF/IFN stimulation on days 2–4 and 17–19 of the cycle, and LTR‐II expression on days 8–10 of the cycle was unchanged after cell stimulation with any factor. Leukotriene B₄ level increased after BSC incubation with luteotropic factors during all examined days of the cycle and after cytokine stimulation at early‐ and mid‐luteal stages, whereas luteolytic factors stimulated LTC₄ secretion over the entire cycle. Leukotriene B₄ stimulated P4 secretion at the mid‐luteal stage and stimulated NO secretion during all examined phases. Leukotriene B₄ stimulated PGE₂ secretion at the early‐ and mid‐luteal stage. Leukotriene C₄ inhibited P4 secretion at the mid‐ and regressing‐luteal stage, stimulated NO (entire cycle) and PGF_2α at mid‐ and regressing‐luteal phases. Leukotrienes modulate steroidogenic cells functions, depending on the stage of the cycle. Leukotriene B₄ plays a luteotropic role stimulating P4 and PGE₂ secretions; LTC₄ stimulates the secretion of luteolytic factors and enhances the luteolytic cascade within BCL.     

牛产后不发情的繁殖机理及影响因素

为了缩短分娩到发情、再次受胎的间隔，提高牛的繁殖效率，国内外，尤其是国外，对牛的产后不发情期进行了大量的研究。本文就牛产后期的繁殖机制和影响因素进行了综述，以便根据实际情况，设计缩短分娩到发情、再次受胎间隔的方案。     

影响牛卵母细胞体外成熟的因素

本文就牛体外受精的关键环节之一体外成熟,阐述了卵母细胞质量、培养基、激素、生长因子、血清、卵泡液及颗粒细胞对其的影响。     

营养因子对降低鸡热应激的研究进展

本文从调控日粮中有关维生素(VE、VC等)、无机元素(Cr、Na、K等)、能量浓度、氨基酸平衡以及应用中草药添加剂等营养角度,全面综述了营养因素对降低鸡热应激的研究进展.     

营养因子对降低鸡热应激的研究进展

本文从调控日粮中有关维生素（VE、VC等）、无机元素（Cr、Na、K等）、能量浓度、氨基酸平衡以及应用中草药添加剂等营养角度，全面综述了营养因素对降低鸡热应激的研究进展。     

致奶牛皱胃左方变位的营养性因素分析

奶牛皱胃左方变位可导致产奶量下降,或继发酸中毒和酮病,甚至被淘汰和死亡。随着国内奶牛规模化养殖的发展和产奶量的提高,发病率不断升高,严重地制约着我国奶牛业的发展。本文从营养角度分析归纳了该病病因的国内外研究概况,从过渡期低饲耗、产后代谢病、引导饲喂、产后精饲及体况评分等方面进行系统综述,为预防奶牛皱胃左方变位的发生提供参考。     

Variations in Seroprevalence and Host Factors for Bovine Anaplasmosis in Illinois

Hungerford, L.L. and Smith, R.D., 1997. Variations in seroprevalence and host factors for bovine anaplasmosis in Illinois. Veterinary Research Communications, 21 (1), 9-18.The modified card agglutination test (MCAT) was used to detect antibodies to Anaplasma marginale in 4994 samples collected from market cattle through the Brucellosis Eradication Program in Illinois. The MCAT reactor rate in the sample was 6.4%. The statewide prevalence estimate increased to between 7.1% and 10.7% when corrected for sampling distribution and test sensitivity and specificity. While the sample reactor rate measures the proportion of infected cattle moving through the market system and into new herds, consideration of the sampling proportions and test characteristics is important when estimating the overall prevalence. Cows were found to be at decreased risk relative to male cattle in lower-prevalence areas, but the risk was similar in higher-prevalence areas. In both higher- and lower-prevalence areas, the risk for seropositivity increased from 1 year of age onwards, but the rate of increase with age was greater in the higher-prevalence areas. Calves, however, had higher seroprevalence levels than 1-2-year-old animals. The risk was highest for Angus and Angus-Hereford cross cattle, while dairy cattle showed a decreased risk in the whole sample, but not when the analyses were stratified by prevalence level. There was a higher concentration of dairy cattle in areas with lower prevalence levels.     

牛卵母细胞体外成熟的影响因素

卵母细胞的体外成熟受多种因素的干扰和制约,不同种类、不同因素、不同的实验室条件等对卵母细胞的生长发育影响均很大。随着卵母细胞体外成熟技术的不断改进和完善,提高牛卵母细胞体外成熟的数量和质量以及充分利用良种资源等的研究就具有十分重要的意义。从体外成熟的作用机制、卵母细胞的获取、激素、成熟时间及人为操作等因素对牛卵母细胞体外成熟的影响进行了综述。     

Effect of Growth Factors on Bovine Blastocyst Development in a Serum-Free Medium

Shamsuddin, M.: Effect of growth factors on bovine blastocyst development in a serum-free medium. Acta vet. scand. 1994, 35, 141-147. - To investigate the effect of growth factors on pre-implantation development, bovine zygotes, produced by in vitro fertilization (IVF) of in vitro-matured (IVM) oocytes, were cultured in a serum-free medium to which the following growth factors were added one at a time: epidermal growth factor (EGF), acidic fibroblast growth factor (a-FGF), insulin-like growth factor-II (IGF-II), platelet-derived growth factor from human platelets (PDGF), and platelet-derived growth factor-AB, human, recombinant (PDGF-AB). All growth factors were added at a dose of either 10 or 50 ng/ml, except PDGF which was added at a dose of either 5 or 15 ng/ml. The control medium was TCM 199 supplemented with sodium pyruvate (0.25 mmol/1), BSA (10 mg/ml), insulin (5 μg/ml), transferrin (5 μg/ml), and sodium selenite (5 ng/ml). Embryos were cultured for 8 days (day of insemination = Day 0). The mean percentages of first cleavage on Day 2 varied from 67% to 86% and the differences between the 2 doses, or between the control and growth factor- treated groups were not significant (p≥0.13). The effects of the two doses on subsequent development up to the blastocyst stage did not differ either (p≥0.12). There was no stimulatory effect of any of the used exogenous growth factors on embryo development up to the morula or blastocyst stage on Day 7, or blastocyst stage on Day 8. Moreover, medium supplemented with PDGF had fewer blastocysts than the control (p≤0.03). The results indicate that growth factor supplementation may not necessarily increase the yield of blastocysts from bovine IVM-IVF oocytes in a serum-free medium.     

牛早期胚胎发育影响因子研究进展

早期胚胎的死亡给畜牧业的发展带来了巨大的经济损失,本文分析了影响牛早期胚胎发育的诸多因素,阐述了黄体功能对早期胚胎发育的影响,指出生长因子和细胞因子可能是非人为因素中早期影响胚胎发育的最重要的因素。     

不同因素对牛卵母细胞体外成熟培养效果的影响

文章主要从采集方法、性周期阶段以及培养液中FBS浓度3个方面对牛卵母细胞体外成熟的影响进行了分析。结果表明：①不同采卵方法的采卵效果存在差异,但成熟培养和体外受精情况差异不显著（P〉0．05）;②从卵泡期和黄体期卵巢采集到的卵母细胞的体外成熟率和卵裂率分别,为59.7%,56．6％和39．5％、36．6％,没有显著差异（P〉0．05）;③培养液中添加20％FBS组的卵母细胞成熟率和卵裂率显著高于10%FBS和30%FBS组（P〈0．05）.