Coleman J, Pierce K M, Berry D P, Brennan A, Horan B
Teagasc, Moorepark Dairy Production Research Centre, Fermoy, Co Cork, Ireland.
J Dairy Sci. 2009 Oct;92(10):5258-69. doi: 10.3168/jds.2009-2108.
Three genetic groups of Holstein-Friesian dairy cows were established from within the Moorepark (Teagasc, Ireland) dairy research herd: LowNA, indicative of the Irish national average-genetic-merit North American Holstein-Friesian; HighNA, high-genetic-merit North American Holstein-Friesian; HighNZ, high-genetic-merit New Zealand Holstein-Friesian. Genetic merit in this study was based on the Irish total merit index, the Economic Breeding Index. Animals from within each genetic group were randomly allocated to 1 of 2 possible post-European Union-milk-quota pasture-based feeding systems (FS): 1) The Moorepark (MP) pasture system (2.64 cows/ha and 500 kg of concentrate supplement per cow per lactation) and 2) a high output per hectare (HC) pasture system (2.85 cows/ha and 1,200 kg of concentrate supplement per cow per lactation). A total of 126, 128, and 140 spring-calving dairy cows were used during the years 2006, 2007, and 2008, respectively. Each group had an individual farmlet of 17 paddocks, and all groups were managed similarly throughout the study. The effects of genetic group, FS, and the interaction between genetic group and FS on reproductive performance, body weight, body condition score, and blood metabolite concentrations were studied using mixed models with factorial arrangements of genetic groups and FS. Odds ratios were used in the analysis of binary fertility traits, and survival analysis was used in the analysis of survival after first calving. When treatment means were compared, the HighNA and HighNZ genotypes (with greater genetic merit for fertility performance) had greater first-service pregnancy rates and had a greater proportion of cows pregnant after 42 d of the breeding season than the LowNA group. Both HighNA and HighNZ genotypes were submitted for artificial insemination earlier in the breeding season and had greater survival than the LowNA genotype. There was no significant FS or genotype by FS interactions for any of the reproductive, blood metabolite, body weight, or body condition score measures. The results demonstrate that increased genetic merit for fertility traits resulted in improved reproductive performance and that the poor reproductive capacity of inferior-genetic-merit animals for fertility was not improved through concentrate supplementation at pasture.
从爱尔兰摩尔帕克（Teagasc）奶牛研究畜群中建立了荷斯坦-弗里生奶牛的三个基因组：LowNA，代表爱尔兰全国平均遗传 merit 的北美荷斯坦-弗里生奶牛；HighNA，高遗传 merit 的北美荷斯坦-弗里生奶牛；HighNZ，高遗传 merit 的新西兰荷斯坦-弗里生奶牛。本研究中的遗传 merit 基于爱尔兰总 merit 指数，即经济育种指数。每个基因组内的动物被随机分配到欧盟牛奶配额后两种基于牧场的饲养系统（FS）之一：1）摩尔帕克（MP）牧场系统（每公顷 2.64 头奶牛，每头奶牛每个泌乳期补充 500 千克精饲料）和 2）高产量（HC）牧场系统（每公顷 2.85 头奶牛，每头奶牛每个泌乳期补充 1200 千克精饲料）。2006 年、2007 年和 2008 年分别使用了 126 头、128 头和 140 头春季产犊的奶牛。每个组有一个由 17 个围场组成的单独农场，并且在整个研究过程中所有组的管理方式相似。使用具有基因组和 FS 因子安排的混合模型研究了基因组、FS 以及基因组与 FS 之间的相互作用对繁殖性能、体重、体况评分和血液代谢物浓度的影响。比值比用于二元繁殖性状的分析，生存分析用于首次产犊后存活情况的分析。当比较处理均值时，HighNA 和 HighNZ 基因型（在繁殖性能方面具有更高的遗传 merit）的首次输精受胎率更高，并且在繁殖季节 42 天后怀孕的奶牛比例高于 LowNA 组。HighNA 和 HighNZ 基因型在繁殖季节早期都接受了人工授精，并且比 LowNA 基因型具有更高的存活率。对于任何繁殖、血液代谢物、体重或体况评分指标，FS 或基因型与 FS 之间的相互作用均无显著差异。结果表明，繁殖性状遗传 merit 的提高导致繁殖性能的改善，并且低遗传 merit 动物的繁殖能力差并未通过牧场补充精饲料得到改善。
