Fertility is economically important but is hard to quantify and measure in breeding programs which has led extensive breeding programs to ignore fertility in their selection criteria. While female fertility traits have been extensively researched, male fertility traits have been largely ignored. It is estimated that 20 to 40% of bulls have sub-fertility, reducing the number of calves born and profits, highlighting the importance of investigating bull fertility. The most practical measure of male fertility is a bull breeding soundness evaluation (BBSE) which assesses structure as well as semen quality and quantity. Generally, traits recorded in a BBSE are neither genetically evaluated nor used for selection in breeding programs. All traits recorded during a BBSE were analysed through a series of univariate and bivariate linear mixed models using a genomic relationship matrix to estimate genetic parameters. All genotype and phenotype data were obtained from a Tropical Composite commercial cattle population and imputed to 27,638 single nucleotide polymorphisms (SNPs) with a total of 2,613 genotyped animals with BBSE records ranging from 616 to 826 animals depending on the trait. The heritabilities of the 27 traits recorded during a BBSE ranged from 0.02 to 0.49. Seven of the male fertility traits were recommended to be included in a breeding program based on their heritability and their phenotypic and genetic correlations. These traits are scrotal circumference, percent normal sperm, proximal droplets, distal midpiece reflex, knobbed acrosomes, vacuoles/teratoids and sheath score. Using these seven traits in a breeding program would result in higher calving rates, increasing production and profitability.

中文翻译：

---

热带复合牛群一岁雄性繁殖性状的遗传参数

生育力在经济上很重要，但在育种计划中很难量化和测量，这导致广泛的育种计划在选择标准中忽视了生育力。虽然女性生育力特征已被广泛研究，但男性生育力特征在很大程度上被忽视。据估计，20%至40%的公牛生育力低下，导致产犊数量和利润减少，凸显了调查公牛生育力的重要性。男性生育力最实用的衡量标准是公牛育种健全性评估 (BBSE)，它评估结构以及精液质量和数量。一般来说，BBSE 中记录的性状既不会进行遗传评估，也不会用于育种计划中的选择。BBSE 期间记录的所有性状均通过一系列单变量和双变量线性混合模型进行分析，使用基因组关系矩阵来估计遗传参数。所有基因型和表型数据均从热带复合商业牛群中获得，并归因于 27,638 个单核苷酸多态性 (SNP)，总共 2,613 只基因分型动物，根据性状，BBSE 记录范围从 616 到 826 只动物不等。BBSE 期间记录的 27 个性状的遗传力范围为 0.02 至 0.49。根据其遗传力及其表型和遗传相关性，建议将七种雄性生育性状纳入育种计划。这些特征是阴囊周长、正常精子百分比、近端液滴、远端中段反射、球形顶体、液泡/畸胎瘤和鞘评分。在育种计划中使用这七个性状将导致更高的产犊率、增加产量和盈利能力。