提高鹿双胎的技术措施

统计几万只家养梅花鹿,其双胎率为3.00%,与奶牛的2.98%接近;统计上万只马鹿,其双胎率仅在1‰。近廿年来,经应用鹿的现代遗传育种技术、生物技术、茸鹿杂交优势利用技术、提高营养水平方法和鹿的人工授精新技术等现代繁殖技术,可明显提高梅花鹿和马鹿及其杂种鹿的双胎率,使其分别达10.00%和1.00%以上,取得显著增效结果,现简述如下:选择产双胎遗传性稳定的母鹿留种,会年年产双胎,其雌性后裔会代代产双胎。它们不受营养、种公鹿等其他因素的影响。应用甾体激素免疫(双羔苗Fecundin)技术在9月中旬至下旬,在健康壮龄经产母梅花鹿的颈侧皮下注射,…     

双胎素免疫提高母羊繁殖力的研究与应用

双胎素免疫是激素免疫中最有效、最适用的方法，具有微量、高效、安全和廉价的特点，不存在激素残留的危害，只提高双羔率，而不产生3羔、4羔，是提高母羊繁殖力的主要技术途径。现就双胎素免疫在提高母羊繁殖力方面的研究与应用做一综述。     

提高鹿双胎的技术方法

经统计几万只家养梅花鹿的双胎率为3.00%,与奶牛的2.98%接近,上万只马鹿的双胎率仅在1‰。近廿年来,经应用鹿的现代遗传育种技术、生物技术、茸鹿杂交优势利用技术、提高营养水平方法和鹿的人工授精新技术等现代繁殖技术,可明显提高梅花鹿和马鹿及其杂种鹿的双胎率分别达10.00%和1.00‰以上,能取得显著增效结果,现简述如下:1选择产双胎遗传稳定的母鹿留种,把属于遗传因素而产双胎的母鹿留种,会年年产双胎,其雌性后裔会代代产双胎。它们不受营养、种公鹿等其它因素的影响,应选留这些鹿。2应用甾体激素免疫(双羔苗Fecundin)技术在9月中旬至下…     

从激素和基因水平探讨提高母猪窝产仔数的研究进展

综述了从激素和基因水平探讨提高母猪窝产仔数的研究进展。讨论了由于不同激素水平失调导致胚胎死亡，降低窝产仔数的主要原因；指出利用分子生物学技术，探测猪DNA标记；分析遗传标记与窝产仔数的遗传连锁关系，可以提高母猪窝产仔数选择的准确性和遗传进展。     

激素诱导母牛多胎试验

发展乳牛和肉牛生产的关键制约因素之一是母牛的繁殖效率，即在单位时间内母牛能够繁殖后代的能力。Niein等(1989)通过对大量母牛产犊资料进行统计分析，认为在自然状况下牛的双胎率极低．仅为O．15-2．99％。自30年代起，国内外学者利用各种技术手段开展人工诱导多胎的研究，使双胎率达到20-70％。张文等(2001)采用促性腺激素处理，     

应用激素提高母牛繁殖率效果研究

应用激素诱导母牛超数排卵,提高母牛繁殖率。选择３个试验组合,即ＦＳＨ＋ＬＨＲＨ－Ａ３试验组、ＰＭＳＧ＋ＡＰＭＳＧ试验组和三合激素＋ＬＨ试验组。选择条件大致相同的空怀母牛３６头,随机分为３组,每组各１２头,饲养管理基本一致。结果ＦＳＨ＋ＬＨＲＨ－Ａ３试验组母牛１２头,情期受胎９头,受胎率７５．０％,产犊１２头,其中产双胎３头,双胎率为３３．３％;ＰＭＳＧ＋ＡＰＭＳＧ试验组母牛１２头,情期受胎８头,受     

人工诱导肉牛孪生的研究进展

人工诱导牛孪生可以提高肉牛的繁殖率,近几十年来诱导双胎的研究涉及遗传选择、激素诱导、激素免疫、胚胎移植等许多领域。并取得了较大的成果。     

同期发情、超数排卵+人工授精诱导肉牛产双胎的初步试验

为了提高能繁母牛的生产效率,验证肉牛产双胎技术的可行性,笔者开展了利用同期发情、超数排卵+人工授精的方式诱导肉牛产双胎的初步试验,选择了29头试验牛,使用孕酮阴道栓(CIDR)+雌二醇(E2)+黄体酮(P4)+促卵泡素(FSH)+前列腺素F2α(PGF2α)+促黄体素释放激素(LHRH-A3)法进行试验处理,人工诱导肉牛产双胎。结果表明:共产双胎犊牛7头,激素处理后肉牛产双胎率平均达到35%。说明应用同期发情、超数排卵+人工授精的方法对母牛人工诱导生产双胎是可行的。     

应用激素提高母牛受胎效果的试验

为了提高母牛冻配的同期发情率、受配率及受胎率，观察应用激素提高奶牛繁殖率的效果进行了本试验。1材料与方法1．1试验牛选择经直检确定为空怀、生殖器官正常、产后40d以上的母牛。1．2激素孕马血清促性腺激素：内蒙古自治区赤峰博恩药业有限公司生产。三合激素：宁波第二激素厂生产（为甲酸雌乙醇、黄体酮、丙酸睾酮的复方制剂）。促排卵素2号（多种氨基酸合成的激素），     

牛双胎生产技术 Ⅰ.技术开发动向和课题

一、序言肉牛生产的主要成本是繁殖母牛的维持需要费用。也就是说,每头母牛产犊数的增多与经济效益的提高相联系。于是,双犊生产则有可能成为最高效率地增产肉食资源的手段。迄今为止,一般采用3种方法生产双胎:(一)选择具有易产双胎遗传性状的牛生产双胎;(二)实验性地配合注射促性腺激素诱发多胎;(三)试行使用胚胎移植技     

黄牛双胎素的研究

黄牛为单胎动物，对豫西７５０００头秦川及秦川杂种母牛连续两年（１９９０～１９９１）的调查资料表明，黄牛的自然双胎率为０．００７８％。１９９０～１９９２年，我们利用超数排卵原理，在豫西地区对５１８头秦川及秦川杂种母牛进行试验，研究出了一种复合激素配方。将该复合激素于发情周期第１７～１８天注射于２０７头母牛的左臀部肌肉，待发情后配种，使母牛每个情期双卵发育率达到７５．８４％，双卵排放率达到７０．０４％，受双胎率达到４３．３１％，活产双犊率达到２２．９２％。试验证明，使用该双胎素可大大提高母牛双胎率，为加速养牛业的发展开辟了一条新途径。     

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.     

Twinning in cattle: I. Foundation animals and genetic and environmental effects on twinning rate

Foundation cows were selected using prior records from one of two sources, private herds or other projects at the Research Center. Comparing twinning rates before and after selection, the repeatability was lower for those from the first (.08) than for those from the second (.16) source with a combined value of .12. Realized heritability of single-parity twinning rate estimated from selection of parents and response in daughters of foundation females was .06. Paternal half-sib estimate of heritability of twinning rate was .02 +/- .07. Estimates of repeatability computed from calving records of females born in the project indicate that permanent environmental effects on twinning rate in cattle are small. Mean calving rate of females born in the project was 1.11 in the data set that included all data and 1.09 in the data set that excluded females from highly selected parents. Twinning rate was greater (P less than .05) in fall than in spring calving (1.13 vs 1.06). Data on twinning rate of a sample of the Swedish Friesian breed were summarized. Mean twinning rate of the Swedish Friesian breed is 2.57%. Age adjusted mean twinning rate of daughters of 32 half-sib sons of one particular Swedish Frieisan sire averaged 5.4% and ranged from .9% to 13.6%. There was no indication of a bimodal distribution, which would be expected if a single gene with a major effect on twinning rate were segregating. The estimated genetic standard deviation (sigma-xn) for mean twinning rates of the 32 sire progeny groups was 1.8%. Observed range among son progenies was .127 or 7.2 sigma-xn, in reasonable agreement with the hypothesis that twinning rate in this population is inherited as a quantitative trait.     

Confirmation of quantitative trait loci using a low-density single nucleotide polymorphism map for twinning and ovulation rate on bovine chromosome 5

Traditional genetic selection in cattle for traits with low heritability, such as reproduction, has had very little success. With the addition of DNA technologies to the genetic selection toolbox for livestock, the opportunity may exist to improve reproductive efficiency more rapidly in cattle. The US Meat Animal Research Center Production Efficiency Population has 9,186 twinning and 29,571 ovulation rate records for multiple generations of animals, but a significant number of these animals do not have tissue samples available for DNA genotyping. The objectives of this study were to confirm QTL for twinning and ovulation rate previously found on BTA5 and to evaluate the ability of GenoProb to predict genotypic information in a pedigree containing 16,035 animals when using genotypes for 24 SNP from 3 data sets containing 48, 724, or 2,900 animals. Marker data for 21 microsatellites on BTA5 with 297 to 3,395 animals per marker were used in conjunction with each data set of genotyped animals. Genotypic probabilities for females were used to calculate independent variables for regressions of additive, dominance, and imprinting effects. Genotypic regressions were fitted as fixed effects in a 2-trait mixed model analysis by using multiple-trait derivative-free REML. Each SNP was analyzed individually, followed by backward selection fitting all individually significant SNP simultaneously and then removing the least significant SNP until only significant SNP were left. Five significant SNP associations were detected for twinning rate and 3 were detected for ovulation rate. Two of these SNP, 1 for each trait, were significant for imprinting. Additional modeling of paternal and maternal allelic effects confirmed the initial results of imprinting done by contrasting heterozygotes. These results are supported by comparative mapping of mouse and human imprinted genes to this region of bovine chromosome 5.     

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。     

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.     

奶牛双胎的发生及其对奶业生产的影响

奶牛在一个发情周期内如果同时排出两个成熟卵子，经过受精和发育，就可能出现双胎现象。奶牛双胎的发生与遗传、产奶量、胎次、受孕年份和季节等因素有关。由于奶牛双胎出现了异性孪生母犊不育、胎衣不下率升高、胎间距延长、流产率和难产率升高、胎儿成活率降低等负面影响。因此，奶牛双胎对奶业生产是不利的。如果能结合性别控制等先进技术，奶牛双胎将有很大的发展前景。     

Association of a single nucleotide polymorphism in SPP1 with growth traits and twinning in a cattle population selected for twinning rate

Continued validation of genetic markers for economically important traits is crucial to establishing marker-assisted selection as a tool in the cattle industry. The objective of the current study was to evaluate the association of a SNP (T(9)/T(10)) in the osteopontin gene (SPP1) with growth rate in a large cattle population spanning multiple generations and representing alleles from 12 founding breeds. This population has been maintained at the US Meat Animal Research Center since 1981 and subjected to selection for twinning rate. Phenotypic records for this population included twinning rate and ovulation rate, providing an opportunity to examine the potential effects of SPP1 genotype on reproductive traits. A set of 2,701 animals was geno-typed for the T(9)/T(10) polymorphism at SPP1. The geno-typic data, including previously genotyped markers on chromosome 6 (BTA6), were used in conjunction with pedigree information to estimate genotypic probabilities for all 14,714 animals with phenotypic records. The genotypic probabilities for females were used to calculate independent variables for regressions of additive, dominance, and imprinting effects. Genotypic regressions were fit as fixed effects in a mixed model analysis, in which each trait was analyzed in a 2-trait model where single births were treated as a separate trait from twin births. The association of the SPP1 marker with birth weight (P < 0.006), weaning weight (P < 0.007), and yearling weight (P < 0.003) was consistent with the previously reported effects of SPP1 genotype on yearling weight. Our data supports the conclusion that the SNP successfully tracks functional alleles affecting growth in cattle. The previously undetected effect of the SNP on birth and weaning weight suggests this particular SPP1 marker may explain a portion of the phenotypic variance explained by QTL for birth and HCW on BTA6.     

Economic values and selection index in different Angus‐Nellore cross‐bred production systems

Bioeconomic models were developed to calculate economic values (EV) for economically important traits in beef cattle, to evaluate the impact of these traits on production profitability, to assess possible market changes with a payment system and to develop economic selection indexes for Angus cattle for two production systems. Two beef cattle production systems were simulated as follows: a cow‐calf cycle (CC) and a complete cycle (CoC). Following selection, positive changes in the EV were observed. In the CC, each 1.0% increment in weaning weight (WW), weaning rate (WR) and pregnancy rate (PR) resulted in increases in US$ 1.30, US$ 3.68 and US$ 3.55 per cow/year in profit, respectively. In the CoC, EV of US$ 1.01, US$ 1.79, US$ 1.19, US$ 1.34, US$ 6.84 and US$ 7.86 per cow/year were obtained for WW, year weight, yearling weight, final weight, WR and PR, respectively. The payment system for carcass quality showed that the scenario considering that 100% of the animals displayed uniform carcasses exhibited the highest EV and was considered optimal. Considering the sensitivity analysis, the price paid per animal was the factor that most affected the EV in both systems. The selection indexes obtained may be used in similar production systems, and the use of EV and selection indexes are important tools for any production system with positive change in profit after selection.     

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.