Animal & Veterinary Sciences, Scotland's Rural College, Easter Bush, Midlothian EH25 9RG, United Kingdom.
Animal & Veterinary Sciences, Scotland's Rural College, Easter Bush, Midlothian EH25 9RG, United Kingdom.
J Dairy Sci. 2014;97(4):2455-61. doi: 10.3168/jds.2013-7319. Epub 2014 Feb 15.
Currently, breeding values for dairy goats in the United Kingdom are not estimated and selection is based only on phenotypes. Several studies from other countries have applied various methodologies to estimate breeding values for milk yield in dairy goats. However, most of the previous analyses were based on relatively small data sets, which might have affected the accuracy of the parameter estimates. The objective of this study was to estimate genetic parameters for milk yield in crossbred dairy goats in lactations 1 to 4. The research was based on data provided by 2 commercial goat farms in the United Kingdom comprising 390,482 milk yield records on 13,591 dairy goats kidding between 1987 and 2012. The population was created by crossing 3 breeds: Alpine, Saanen, and Toggenburg. In each generation, the best-performing animals were selected for breeding and, as a result, a synthetic breed was created. The pedigree file contained 28,184 individuals, of which 2,414 were founders. The data set contained test-day records of milk yield, lactation number, farm, age at kidding, and year and season of kidding. Data on milk composition was unavailable. Covariance components were estimated with the average information REML algorithm in the ASReml package (VSN International Ltd., Hemel Hempstead, UK). A random regression animal model for milk yield with fixed effects of herd test day, year-season, and age at kidding was used. Heritability was the highest at 200 and 250d in milk (DIM), reaching 0.45 in the first lactation and between 0.34 and 0.25 in subsequent lactations. After 300 DIM, the heritability started decreasing to 0.23 and 0.10 at 400 DIM in the first and subsequent lactations, respectively. Genetic correlation between milk yield in the first and subsequent lactations was between 0.16 and 0.88. This study found that milk yields in first and subsequent lactations are highly correlated, both at the genetic and phenotypic level. Estimates of heritability for milk yield were higher than most of the values reported in the literature, although they were in the range reported in this species. This should facilitate genetic improvement for the population studied as part of a broader multi-trait breeding program.
目前，英国的奶山羊繁殖值尚未进行估算，选择仅基于表型。其他国家的几项研究已经应用了各种方法来估算奶山羊的产奶量繁殖值。然而，之前的大多数分析都是基于相对较小的数据集，这可能会影响参数估计的准确性。本研究的目的是估计第 1 至 4 泌乳期杂交奶山羊产奶量的遗传参数。该研究基于英国 2 家商业山羊养殖场提供的数据，这些数据包括 1987 年至 2012 年间 13591 只奶山羊的 390482 个产奶记录。该群体是通过杂交 3 个品种：阿尔卑斯山羊、萨能山羊和托根堡山羊创建的。在每一代中，表现最好的动物都会被选来繁殖，因此创建了一个合成品种。系谱文件包含 28184 个人，其中 2414 人为创始人。数据集包含产奶量、泌乳次数、农场、产仔年龄以及产仔年份和季节的测试日记录。牛奶成分数据不可用。方差分量使用 ASReml 包（VSN International Ltd.，英国赫默尔亨普斯特德）中的平均信息 REML 算法进行估计。使用产奶量的随机回归动物模型，固定效应为畜群测试日、年份-季节和产仔年龄。在第 1 泌乳期，200 和 250 天的泌乳量（DIM）的遗传力最高，达到 0.45，随后的泌乳期在 0.34 至 0.25 之间。在 300DIM 之后，第 1 和随后的泌乳期的遗传力开始分别下降至 0.23 和 0.10。第 1 和随后的泌乳期产奶量之间的遗传相关性在 0.16 至 0.88 之间。本研究发现，第 1 和随后的泌乳期的产奶量在遗传和表型水平上高度相关。产奶量的遗传力估计值高于文献中报道的大多数值，尽管它们在该物种报告的范围内。这将有助于作为更广泛的多性状育种计划的一部分，对所研究的群体进行遗传改良。
