提高奶牛繁殖力的几项措施

奶牛的繁殖力在生产实践中具有重要意义．繁殖水平的高低直接影响牛群的产奶水平和牛场的经济效益。为了提高经济效益，降低成本，提高奶牛的繁殖力，应重点抓好下列几个环节：     

提高奶牛繁殖力的技术措施

采取一切有利措施,提高牛群的繁殖水平,是奶牛生产中的当务之急。笔者根据多年的生产实践体会总结出了行之有效的方法,供同行商榷。1日粮营养水平要平衡能量不足会推迟育成牛的性成熟和适配年龄,延迟产后发情,严重时会出现发情周期停止,或有发情周期但不表现发情征状;对于妊娠的母牛,能量不     

奶牛繁殖力的影响因素及提高措施

繁殖在奶牛生产中是一项很重要的工作。因而，不少奶牛饲养场，户常向本刊询问如何提高奶牛繁殖力的问题，为了统一答覆这些场户， 本期刊出杨利国，周东蕊二位先生写的此篇文章，可供参阅。《中国奶牛》编辑部     

提高奶牛繁殖力的技术措施试验

奶牛繁殖力的高低,直接影响到奶牛的产犊间隔、产奶性能的发挥和奶牛生产的经济效益.近年来,我场的奶牛繁殖力一直徘徊不前,情期受胎率在60%左右,造成奶牛生产中的损失.为提高奶牛繁殖力,我们自2003～2005年应用不同的技术措施,在繁殖力上搞试验,通过两年来的技术试验,奶牛情期受胎率达70%,收到了满意的效果,具体试验方法如下：     

奶牛常见繁殖障碍的处理

繁殖是奶牛正常生育的前提和基础,牛群的增殖,正常的产奶,良种的选择以及养奶牛的经济效益都与繁殖相关。现就各种原因造成的奶牛繁殖障碍疾病及处理,提出以下几点看法及经验。1子宫内膜炎引起的繁殖障碍炎性产物和细菌毒素的影响,奶牛出现周期性紊乱,损害精子活动,致使配种不孕,着床困难,发生早期胚胎消失,继发子宫内膜炎。1·1发生原因分娩过程产道感染,助产时消毒不严,剥离胎衣、治疗子宫脱出时消毒不彻底,方法不得当;输精时不仔细,损伤阴道和子宫颈;发情判断不准,多次反复输精,畜体患有全身性传染病,如结核病、布氏病和产后继发子宫弛缓…     

影响奶牛繁殖力的因素及对策

奶牛的繁殖力是衡量奶牛经济价值的重要指标，提高奶牛繁殖力可增加奶牛经济利用价值。影响奶牛繁殖力的因素主要有种公牛、母牛、人为操作等，提高奶牛繁殖力的措施主要是选种选配、饲养管理、疾病治疗、药物处理、配种技术、孕情检查、接产助产等。     

提高奶牛繁殖力的主要措施

奶牛的繁殖力在生产实践中具有重要的意义。繁殖力的高低，直接影响到奶牛的产犊间隔。产奶性能的发挥和奶牛生产的经济效益。目前我国奶牛的繁殖力较低。与畜牧业发达国家尚存在一定的差距。如何迅速而有效地提高奶牛的繁殖力，已成为我国养牛业十分关注的问题。现将提高奶牛繁殖力的几点主要措施作一概述。     

蛋白质对奶牛繁殖力的影响

蛋白质在牛体内占有特殊重要的地位，它不仅是畜产品(牛奶、牛肉等)的主要成分，而且是生命的物质基础．表现出种类和功能的多样性，如作为机体新陈代谢催化剂的酶、运输氧气的血红蛋白、参加免疫的抗体、具有调节新陈代谢作用的激素等，都是有蛋白质构成的。     

影响奶牛产奶能力的因素

培育高产奶牛，对于提高饲料报酬，降低饲养成本，增加产奶量，提高经济效益等都有着密切的关系。从养奶牛生产实践中来看，影响奶牛产奶能力的因素很多，主要包括遗传因素、生理因素和环境因素三大方面，其中选育工作是创高产的前提，饲养管理是发挥产奶性能的关键。     

影响家畜超数排卵效果的因素

超数排卵(MO,MultipleOvulation)乃是胚胎移植所需胚胎的主要来源。它充分挖掘良种母牛的遗传潜力,向社会提供大量的优质胚胎。本文阐述了国内外超数排卵的发展情况,从不的角度分析了影响超排效果的几个因素。     

影响奶牛乳蛋白生产的因素及应对措施

奶牛乳蛋白的合成受许多因素的影响，如奶牛的品种、基因、泌乳特征和环境等因素。本文主要介绍了乳蛋白生理、评估乳蛋白的参数，论述影响乳蛋白生产较难控制和较易控制的因素及应对措施，为牧场乳蛋白的生产提供参考。     

影响奶牛乳成分因素的研究进展

近年来我国奶牛养殖行业发展迅速,人们在专注于提高奶牛产奶量的同时,开始关注如何提高乳品质。奶牛自身的遗传与非遗传因素以及奶牛生活环境显著影响着乳成分,伴随奶牛品种和所处环境的变化,其乳成分与品质也会发生改变。在生产中植物提取物以其无毒、无害、无副作用等多种优势成为改善乳品质的天然添加剂,可以提高奶牛的泌乳性能、改善乳成分,具有使用价值和应用前景。本文通过综述奶牛品种、环境及天然植物提取物等多种饲料添加剂对乳成分的影响,以期为在生产实践中提高乳品质等提供理论依据。     

Factors Affecting Plasma Pregnancy-associated Glycoprotein 1 Concentrations Throughout Gestation in High-producing Dairy Cows

This study was designed to establish the factors, if any, which could affect plasma pregnancy-associated glycoprotein-1 (PAG-1) expression in a study population of 87 pregnant, high-producing dairy cows. The factors examined were: semen providing breed (Holstein-Friesian vs Limousin), outcome of gestation (male vs female newborn, and singleton vs twin pregnancies), lactation number, milk production at pregnancy diagnosis, plasma progesterone concentration, season of gestation (warm period, March–November vs cool period, December–February), and day of gestation (40, 90, 120, 150, 180 and 210). Pregnancy was diagnosed by transrectal ultrasound on day 40 post-insemination and by palpation per rectum on days 90, 120, 150, 180 and 210. Blood samples were collected from each animal immediately before each pregnancy diagnosis. The relative contributions of the different factors on PAG-1 concentrations were evaluated by GLM repeated measures analysis of variance. No significant effects of the herd, foetal sex, milk production, lactation number and plasma progesterone concentrations were observed. In contrast, twin pregnancy, the use of Limousin semen and conception during the cool period were correlated with significantly increased plasma PAG-1 concentrations throughout gestation. Our data indicate that both cow well-being during early placental development, determined in our conditions by reduced heat stress when conception occurred in the cool season, and crossbreed pregnancies lead to improved PAG-1 production throughout the gestation period.     

Factors Affecting the First Service Conception Rate of Cows in Smallholder Dairy Farms in Bangladesh

The successful outcome of an insemination is a combination of both male and female fertility‐linked factors. We investigated the first service conception rate of cows at artificial insemination (AI) in the smallholder dairy farms in Bangladesh. Frozen straws were prepared from ejaculates of Bos indicus (n = 7) and Bos indicus × Bos taurus (n = 7) AI bulls. Fertility was determined from 6101 first services in cows that were performed by 18 technicians in four regions between April 2004 and March 2005. Pregnancy was diagnosed by rectal palpation between 60 and 90 days post‐insemination. The Asian version of Artificial Insemination Database Application (AIDA ASIA) was used for bulls‐, cows‐ and AI‐related data recording, and later retrieved for analysis. The mean ± SD number of inseminations performed from individual bulls and their conception rates were 436.0 ± 21.6 and 50.7 ± 1.9%, respectively. Logistic regression demonstrated body condition scores (BCS), heat detection signs, months of AI and their interactions had greatest effects (odds ratios: 1.24–16.65, p < 0.04–0.001) on first service conception rate in cows. Fertility differed (p < 0.02–0.001) between the regions, previous calving months, months of AI, BCS, parity and heat detection signs of cows. Inseminations based on mounting activity (n = 2352), genital discharge (n = 3263) and restlessness and/or other signs (n = 486) yielded a conception rate of 53.6%, 48.8% and 50.1%, respectively (p < 0.05). Conception rate between technicians ranged between 43.4% and 58.6% (p < 0.05). The days interval from calving to first service (overall mean ± SD = 153.4 ± 80.6) had relationship (p < 0.001) with BCS, months of previous calving and parity of the cows. Fertility at AI in smallholder farms can be improved by training farmers on nutrition and reproductive management of the cows.     

影响奶牛产后乏情的主要因素

奶牛性成熟之后或产后长时间不发情称为病理性乏情，奶牛的乏情主要是由于不排卵、排卵延迟、卵泡萎缩或静止以及持久黄体所引起。奶牛产后一般40～60d发情，对于14月龄以上不发情的后备牛和产后60d不发情的母牛，应及时检查寻找病原和调整奶牛日粮营养成分。本文主要综述了能量、蛋白质、矿物质元素、微量元素、维生素和内分泌激素对奶牛产后乏情的影响。     

线性模型对影响奶牛产奶性能的主要相关因素分析

利用一般线性模型研究各种因素对奶牛产奶性能的影响。牛场、胎次和产犊季节对奶牛产奶量影响差异极显著(P0.01),随着奶牛胎次的增加,奶牛产奶量增加;夏季产犊的奶牛产奶量最低,冬季产犊的最高;体细胞计数对奶牛产奶量没有显著性影响(P0.05),但随着体细胞数的增加,产奶量下降。牛场、胎次和体细胞计数对乳脂率有极显著的影响(P0.01),第三牛场平均乳脂率为4.38%,显著高于其他三个牛场;随着胎次的增加,乳脂率有下降趋势;随体细胞数增加,乳脂率升高;产犊季节对奶牛乳脂率没有显著影响(P0.05)。牛场、产犊季节和体细胞数对乳蛋白率的影响极显著(P0.01),体细胞数增加,乳蛋白率升高;夏季和秋季产犊的奶牛乳蛋白率较高,春季和冬季较低;胎次对乳蛋白率没有显著影响(P0.05)。表型相关分析表明:SCC与产奶量呈显著负相关(r=-0.158,P0.05),SCS与产奶量相关性接近显著水平(r=-0.140,P=0.055)。SCC/SCS与乳脂率、乳蛋白率呈正相关,但未达到显著性水平(P0.05)。     

Some Factors Affecting Reproductive Success in Crossbred Dairy Cows on Smallholder Farms in Coastal North-East Tanzania

A 2-year longitudinal survey was carried out to investigate factors affecting reproduction in crossbred cows on smallholder farms in and around an urban centre. Sixty farms were visited at approximately 2-week intervals and details of reproductive traits and body condition score (BCS) were collected. Fifteen farms were within the town (U), 23 farms were approximately 5 km from town (SU), and 22 farms approximately 10 km from town (PU). Sources of variation in reproductive traits were investigated using a general linear model (GLM) by a stepwise forward selection and backward elimination approach to judge important independent variables. Factors considered for the first step of formulation of the model included location (PU, SU and U), type of insemination, calving season, BCS at calving, at 3 months postpartum and at 6 months postpartum, calving year, herd size category, source of labour (hired and family labour), calf rearing method (bucket and partial suckling) and parity number of the cow. The effects of the independent variables identified were then investigated using a non-parametric survival technique. The number of days to first oestrus was increased on the U site (p = 0.045) and when family labour was used (p = 0.02). The non-parametric test confirmed the effect of site (p = 0.059), but effect of labour was not significant. The number of days from calving to conception was reduced by hiring labour (p = 0.003) and using natural service (p = 0.028). The non-parametric test confirmed the effects of type of insemination (p = 0.0001) while also identifying extended calving intervals on U and SU sites (p = 0.014). Labour source was again non-significant. Calving interval was prolonged on U and SU sites (p = 0.021), by the use of AI (p = 0.031) and by the use of family labour (p = 0.001). The non-parametric test confirmed the effect of site (p = 0.008) and insemination type (p > 0.0001) but not of labour source. It was concluded that under favourable conditions (PU site, hired labour and natural service) calving intervals of around 440 days could be achieved.     

克拉玛依地区荷斯坦牛超排效果及影响因素的分析

本研究比较了不同年度、季节、超排方法、促卵泡素（FSH）的剂量、超排处理开始时发情周期天数及供体牛年龄对荷斯坦牛超排效果的影响。结果表明，秋季、冬季与夏、春季比较在采卵数和可用胚数方面差异极显著（P〈0．01）。改进方法与常规方法比较采卵数差异极显著（P〈0．01），可用胚数差异显著（P〈0．05），8．0mL、9．4mL、10．0mLFSH剂量之间各项指标均差异显著（P〈0．05）。而超排处理的年度、超排处理开始时发情周期天数及供体牛年龄对荷斯坦牛超排效果影响不显著（P〉0．05）。     

Some Factors Affecting Variation in Milk Yield in Crossbred Dairy Cows on Smallholder Farms in North-East Tanzania

A 2-year longitudinal survey was carried out to investigate factors affecting milk yield in crossbred cows on smallholder farms in and around an urban centre. Sixty farms were visited at approximately 2-week intervals and details of milk yield, body condition score (BCS) and heart girth measurements were collected. Fifteen farms were within the town (U), 23 farms were approximately 5 km from town (SU), and 22 farms approximately 10 km from town (PU). Sources of variation in milk yield were investigated using a general linear model by a stepwise forward selection and backward elimination approach to judge important independent variables. Factors considered for the first step of formulation of the model included location (PU, SU and U), calving season, BCS at calving, at 3 months postpartum and at 6 months postpartum, calving year, herd size category, source of labour (hired and family labour), calf rearing method (bucket and partial suckling) and parity number of the cow. Daily milk yield (including milk sucked by calves) was determined by calving year (p < 0.0001), calf rearing method (p = 0.044) and BCS at calving (p < 0.0001). Only BCS at calving contributed to variation in volume of milk sucked by the calf, lactation length and lactation milk yield. BCS at 3 months after calving was improved on farms where labour was hired (p = 0.041) and BCS change from calving to 6 months was more than twice as likely to be negative on U than SU and PU farms. It was concluded that milk production was predominantly associated with BCS at calving, lactation milk yield increasing quadratically from score 1 to 3. BCS at calving may provide a simple, single indicator of the nutritional status of a cow population.