母牛双胎的利弊及其诱发

诱发母牛双胎是一个很有趣的、正在努力研究的课题。母牛的双胎并不多见。在自然繁殖状况下,母牛的双胎率一般在1—4％。斯坎伦等(1974)报道,在2323次妊娠中有2.8％的双胎率;杨利国(1987)统计了5135头黄牛,双胎率为0.15％,母牛双胎与牛的品种和年龄有一定的关系。肉牛的双胎率高于奶牛,如西门塔尔牛(肉牛)的双胎率为5.18％,黑白花奶牛的双胎     

浅析奶牛“一产双胎”对奶牛场的影响

近年来，我场奶牛的双胎率有上升的趋势（最近四年分别为1．77％，3.38％，3．66％，4．17％）。奶牛“一产双胎”虽然比单胎能产下2倍的犊牛，但是“一产双胎”的产死犊比例、胎衣不下、早产比例等繁殖指标明显比单胎的要高，并给奶牛场带来一系列负面影响。为此，我们对本场近几年产犊原始记录进行了统计，以分析双胎对奶牛生产的影响。     

新生犊牛衰弱的病因及防治

奶牛怀双胎时发生难产的机率会大大升高，此类病例如果得不到及时正确的助产和治疗，后果十分严重。轻的会损伤产道。继发生殖系统疾病，重则危及母牛及胎儿生命，造成巨大的经济损失。现将笔者接诊的一例病例介绍如下。     

西门塔尔奶牛一胎双犊生产性能分析

奶牛一胎双犊可说是有利有弊,一般认为,奶牛一胎双犊,对增加优良种牛后裔有利,应当提倡。也有人认为,奶牛产双犊,如果是异性双犊,母犊大多不孕,而同性双犊,又因出生重偏低,而影响日后生产,应当避免。本文旨在通过对呼图壁种牛场1995-2001年西门塔尔奶牛(荷斯坦奶牛报告较多)一胎双犊有关资料的整理分析,反映一胎双犊在西门塔尔奶牛的胎次分布、双胎率、双胎犊初生重,并重点比较产单胎母牛及产双胎母牛的生产性能,对奶牛实际生产提供依据。     

牛双胎的研究与应用

牛双胎可显著的提高生产效率，对母牛和犊牛没有明显的不良影响，不利之处是异性双胎造成母犊不孕、。双胎是可以遗传的，双亲的影响较大；不同品种间的双胎率差异显著；另外胎次、季节、营养均影响双胎率。目前常用的提高双胎率的方法是通过遗传选择、激素诱导、激素免疫、胚胎移植等方法。但如果结合标记辅助选择法（MAS）、性别控制、及转基因与克隆技术将有助于快速提高双胎率，提高生产效益。     

影响奶牛繁殖力的主因10则

影响奶牛繁殖力的主因１０则白淑声，黄德斌（省畜牧兽医学校１５００１１）于志民，李玉杰（双城市畜牧局）母牛的繁殖力是遗传力较低的性状，主要受环境条件影响。影响奶牛繁殖力的主要因素综述如下：１．产双胎：牛属于单胎动物，双胎率很低，一般不超过３％。产了双胎...     

奶牛围产期疾病的相互关系

用直线回归法对英国南部１０个奶牛场３６０３头泌乳奶牛三个以上产犊季节的围产期疾病之间的相关性进行了评价。犊牛死亡与难产呈强相关。产双胎和难产是造成犊牛死亡的重要预测因子。产双胎同时也是胎衣不下的显著预测因子。胎衣不下、产双胎、犊牛死亡和难产依次为导致阴道排出物的危险致病因子。配前已出现过产双胎、难产、胎衣不下和跛行，都可使配前乳房炎的危险性明显增加。同样地，配前的乳房炎和难产也可使配前跛行的危险性增大。经观察，配前已有过产双胎和跛行的奶牛，其发情期有所缩短，而后者则对第一胎的影响比老龄奶牛要大得多。     

奶牛产双胎的规律分析

笔者调查了江苏省某奶牛场2004~2013年3 209头次中国荷斯坦母牛的产犊记录,探讨胎次与产犊月份对奶牛双胎率的影响;观察了2011~2013年留养的8头异性双胎母犊的繁殖性能。结果表明:奶牛的双胎率为4.4%;双胎率最多的胎次为第三胎,占26.1%,1月份的双胎率最高,占18.3%;8头留养的异性双胎母犊中有4头生殖器官发育正常,并具有正常繁殖能力,占留养的50%。     

热应激条件下奶牛的饲养管理

随着夏季的来临，气温和空气湿度逐渐升高，特别是在我国南部地区的奶牛场，普遍都存在奶牛的夏季热应激。此时，使奶牛尽可能舒适成为保持高产奶牛生产水平的关键。当气温升高到22℃，湿度高于85％时，奶牛即处于应激状态。由于高产奶牛的体内发热量较大，热应激因而更加严重。如果奶牛舍的通风不良，奶牛体热不能很快地散出去，那么高热、高湿及体产热加在一起，将导致奶牛采食量下降、产奶量降低、乳脂率下降，并且会影响繁殖性能。     

选购后备奶牛谨防异性挛生不育牛

在选购奶牛时，除从体型外貌、乳房发育、生长发育等外表和系谱进行选择外．还应重视繁殖性能的选择。尤其在选购犊牛或后备奶牛时．更要谨防异性挛卡不育母牛。正常情况下，奶牛双胎率仅3．5％左右．异性挛生率更低，在监床上只偶尔遇到。但我们在这二年被邀请对两批后备奶牛进行诊断时．却发现异性挛生母牛占60％多．应引起大家注意。     

Twinning in Dairy Cattle

Twinning in dairy cattle is an unavoidable outcome of reproduction and is undesirable because it reduces the overall profitability of a dairy operation through negative effects on cows calving twins as well as on calves born as twins. Cows calving twins are at greater risk for many periparturient reproductive and metabolic disorders than nontwinning herdmates, and incidences of abortion, stillbirth, neonatal calf mortality, and reduced birth weight are greater among twin compared with singleton calves. Twinning is a complex trait with multiple causative factors, and empirical evidence supports a role for both genetic and environmental risk factors in cattle. Risk factors for twinning include genetics, season, parity, ovulation rate, and milk production. The observation that twinning has increased in the dairy cattle population over time suggests a concurrent change in one or more of these causative factors during this same period. At present, dairy farmers and their consultants are ill prepared to make sound-management decisions to mitigate the negative effects of twinning on their operations because of a lack of applied scientific data on management strategies for periparturient dairy cows carrying twin fetuses. A clear understanding of the factors responsible for twinning is essential for future development of strategies to manage twinning in dairy operations.     

Refined mapping of twinning-rate quantitative trait loci on bovine chromosome 5 and analysis of insulin-like growth factor-1 as a positional candidate gene

Twinning in cattle is a complex trait that is associated with economic loss and health issues such as abortion, dystocia, and reduced calf survival. Twinning-rate QTL have been detected previously on BTA5 in the North American Holstein and Norwegian dairy cattle populations and in a USDA herd selected for high twinning rate. In previous work with the North American Holstein population, the strongest evidence for a QTL was obtained from analysis of an extended, multiple-generation family. Using additional animals, an increased density of SNP marker association tests, and a combined linkage and linkage disequilibrium mapping method, we refined the position of this QTL in the North American Holstein population. Two sets of twinning-rate predicted transmitting abilities estimated during 2 different time periods in the North American dairy cattle population were used to provide validation of results. A total of 106 SNP and 3 microsatellites were used to scan the genomic region between 5 and 80 Mb on BTA5. Combined linkage-linkage disequilibrium analysis identified significant evidence for QTL within the 25- to 35-Mb and 64- to 70-Mb regions of BTA5. The IGF-1 gene (IGF1) was examined as a positional candidate gene and an SNP in intron 2 of IGF1 was significantly associated with twinning rate by using both data sets (P = 0.003 and P = 1.05 x 10(-6)). Replication of this association in other cattle populations will be required to examine the extent of linkage disequilibrium with the underlying quantitative trait nucleotide across breeds.     

Natural transmission of Demodex Bovis stiles to dairy calves

Hides from cattle exposed to their infested dams for known periods and from sibling cattle were examined to determine when transmission of Demodex bovis occurred in an experimental dairy herd. Five of the 7 (71.4%) calves exposed to infested dams for 2 days, all 5 calves exposed for 3 days, and 1 calf exposed for 0.5 day became infested. Sibling cattle from 6 dams were examined; each had at least 1 calf that became infested. One dam produced twins, both of which became infested.These observations indicate that calves can acquire mites from an infested dam in 0.5 day and that sibling cattle from an infested dam do not always become infested.     

An economic assessment of twin births in British dairy herds.

The effect of twinning on the subsequent health, production and reproductive performance of dairy cattle was studied by analysing the data derived from 19,755 calvings which occurred during three years on 37 farms. The data formed part of the database of a veterinary practice operating the DAISY dairy cow recording scheme for its dairy farmer clients. The average twinning rate was 2.5 per cent. For first calf heifers the rate was 0.9 per cent, and the rate increased with increasing parity to over 5 per cent for cows calving for their sixth and subsequent lactations. Although they produced more milk than their contemporaries, twin-bearing cows suffered an increased incidence of retained placenta and vulval discharges and their calving to conception interval was extended by 33 days. Furthermore, 35 per cent of these cows were culled compared with 21 per cent of their contemporaries. The benefit of having more calves for sale was reduced owing to 15 per cent of them being born dead. It is calculated that producing twins resulted in an average loss of income of 74 pounds/cow, a deficit of 15 per cent compared with cows having single calves.     

不同类型奶牛场牛奶乳脂率及酸度变化特点研究

奶牛生产方式是影响奶牛奶产量和质量的重要因素。本文通过对兰州市晏家坪奶牛养殖小区、甘肃农业大学实验奶牛场、兰州市个体养殖户三种不同类型奶牛场的牛奶乳脂率及酸度指标分析,表明不同生产方式下牛奶质量差别较大,以相对规模化、集约化生产的奶牛养殖小区牛奶质量最好,个体养殖户牛奶质量较差。因此,在奶牛生产中,采用规模化、集约化的生产模式是保证牛奶质量的重要措施之一。     

中药治疗奶牛乳房炎的研究现状与展望

综述了中药治疗奶牛乳房炎的临床应用、机理和特点,认为中药治疗奶牛乳房炎采用辨证施治方法,毒副作用小且不易产生耐药性;指出了中药治疗奶牛乳房炎存在的问题,主要是基础研究薄弱、生产工艺落后、无固定标准、药品质量难以保证等.由于中药治疗奶牛乳房炎疗效确实,因而潜力巨大.     

陕西泾阳县奶牛品种改良现状、问题及对策

泾阳县是全国奶牛生产五强县之一,奶畜产业规模稳居西北第一,截至2008年3月,全县奶牛存栏26273头,奶牛单产6015．3kg。但在奶牛品种改良中忽视良种奶牛选种选配,轻视后备母牛培育,后裔测定也很不规范。本文通过对泾阳县奶牛品种改良的调查,全面了解剖析了当地奶牛品种改良工作的现状,指出了奶牛品种改良中存在的主要问题并提出了对策性建议,以实现奶牛养殖的良种化。     

How to improve reproductive efficacy from now in Japan? Find out the factors of late lactation to predict postpartum reproductive diseases

Reproductive efficiency and performance in dairy cattle has been declining over the last 20 years in Japan. Recently, this has resulted in serious problems in dairy herds. There have been changes in the animals themselves and in the animal's environment, e.g. the genetic potential for milk yield has improved, the herd size of dairy farms has been expanding, the housing system of dairy cattle has been changing from tie stall to free stall, and total mixed ratio (TMR) feeding systems have become widespread. It is not clear whether the animals have adapted adequately to these environmental changes. Up till now, reproductive management has been undertaken by monitoring animal performance and/or hormonal treatments, and this has resulted in acceptable reproductive performance. However, conception and pregnancy rates have continued to decline, and the calving to calving interval has continued to extend. Consequently, the average parity and the average age at culling in dairy cattle have been declining. The most common causes of culling in dairy cattle are reproductive disorders in Japan. Therefore, in future, prevention of reproductive disorders will be required for both reproductive efficiency and animal welfare. During late pregnancy and the transition from the pregnant, non-lactating state to the non-pregnant, lactating state, dramatic changes are occurring in the dam including an increase in the fetal-placental mass and calving. Thus, the demand for energy, protein and minerals by the conceptus increases, the space within the abdominal cavity and the rumen capacity decreases due to the increased volume of the conceptus, the local immunological relationship between the fetal and maternal placenta dramatically changes, and physiological homeostasis is activated to adapt to these changes. If cattle can't maintain homeostasis before calving, the incidence of reproductive diseases will be greatly increased. We have been examining reproductive, nutritional and immunological factors to predict the occurrence of reproductive disorders as early as possible and to develop strategies to prevent them. It is unlikely that all dairy farms in Japan will be able to improve reproductive performance with general advice, due to the wide variation in feeding systems and management in Japan. Therefore, specific advice needs to be tailored to each herd, based on management systems employed within each herd. We have proposed that it is important to identify common risk factors across herds, to use these factors as an index for disease control and reproductive management and finally to demonstrate the relationship between these factors and fundamental improvement of the reproductive efficiency. We propose this approach with the aim of providing a breakthrough in improving reproductive performance in dairy cattle in Japan. The focus of this review will be that such an approach is important for improvement of the reproductive efficiency in Japanese dairy cows.     

奶牛生物技术育种研究进展

奶业已成为我国农业战略产业的重要组成部分,与发达国家相比,我国奶牛在良种率、产奶量、乳品质等方面仍存在较大差距。面对日益增长的消费量和品质需求,加快奶牛育种显得尤为迫切。本文便针对我国奶业当前发展现状分析了我国奶牛产业发展存在的问题及利用生物技术进行育种的必要性和迫切性。从分子标记辅助选择、QTL 定位、全基因组关联分析、全基因组选择、转基因以及胚胎工程等方面阐述了近些年国内外奶牛生物技术育种研究现状和进展,讨论了目前奶牛生物技术育种过程中存在的问题,以期对我国奶业发展有所裨益。