Animal and Grassland Research and Innovation Centre, Teagasc Moorepark, Fermoy, Co. Cork, Ireland.
Theriogenology. 2011 Jan 1;75(1):172-81. doi: 10.1016/j.theriogenology.2010.08.002. Epub 2010 Sep 27.
A successful outcome to a given service is a combination of both male and female fertility. Despite this, most national evaluations for fertility are generally confined to female fertility with evaluations for male fertility commonly undertaken by individual breeding organisations and generally not made public. The objective of this study was to define a pertinent male fertility trait for seasonal calving production systems, and to develop a multiple regression mixed model that may be used to evaluate male fertility at a national level. The data included in the study after editing consisted of 361,412 artificial inseminations from 206,683 cow-lactations (134,911 cows) in 2,843 commercial dairy and beef herds. Fixed effects associated with whether a successful pregnancy ensued (pregnant = 1) or not (pregnant = 0) from a given service were year by month of service, day of the week, days since calving, cow parity, level of calving difficulty experienced, whether or not the previous calving was associated with perinatal mortality, and age of the service bull at the date of insemination. Non-additive genetic effects such as heterosis and recombination loss as well as inbreeding level of the service bull, dam or mating were not associated with a successful pregnancy; there was no difference in pregnancy rate between fresh or frozen semen. Random effects included in the model were the additive genetic effect of the cow, as well as a within lactation and across lactation permanent environmental effect of the cow; pedigree group effects based on cow breed were also included via the relationship matrix. Temporal differences in the AI technician and service bull were also included as random effects. A difference in five percentage units in male fertility was evident between the average effects of different dairy and beef breeds. The correlation between raw pregnancy rates for bulls with more than 100 services (n = 431) and service bull solutions from the mixed model analysis was 0.66. The correlation between the raw pregnancy rates of 288 technicians with more than 100 services and their respective solutions from the mixed model was 0.35. These low to moderate correlations suggest considerable re-ranking among both service bulls and technicians and suggest possibly a benefit of using a statistical model to better estimate the performance of both service bulls and technicians.
一个给定服务的成功结果是男性和女性生育能力的结合。尽管如此，大多数国家对生育能力的评估通常仅限于女性生育能力，而男性生育能力的评估通常由个别繁殖组织进行，且通常不对外公布。本研究的目的是为季节性产犊生产系统定义一个相关的男性生育力特征，并开发一个多元回归混合模型，该模型可用于在国家层面评估男性生育力。经过编辑，研究中包含的 361412 次人工授精数据来自 2843 个商业奶牛和肉牛群的 206683 次奶牛泌乳（134911 头奶牛）。与特定服务是否成功妊娠相关的固定效应（妊娠=1）或未妊娠（妊娠=0）包括服务的年月、服务的星期几、产犊后的天数、牛的胎次、产犊难易程度、上次产犊是否与围产期死亡有关，以及配种时种公牛的年龄。非加性遗传效应，如杂种优势和重组损失，以及种公牛、母牛或交配的近交水平，与成功妊娠无关；新鲜精液和冷冻精液的妊娠率没有差异。模型中包含的随机效应包括牛的加性遗传效应，以及牛的泌乳内和泌乳间的永久环境效应；还通过相关矩阵包括基于牛品种的谱系群效应。AI 技术员和种公牛的时间差异也被包括为随机效应。不同奶牛和肉牛品种的平均效应之间，男性生育力相差五个百分点。在有 100 多次服务的公牛的原始妊娠率（n=431）与混合模型分析的种公牛解决方案之间存在 0.66 的相关性。在有 100 多次服务的 288 名技术员的原始妊娠率与其各自的混合模型解决方案之间存在 0.35 的相关性。这些低至中度相关性表明，种公牛和技术员之间存在相当大的重新排序，并表明使用统计模型来更好地估计种公牛和技术员的性能可能会有所受益。
