Genetic Correlation of Conformation Traits with Semen Traits in Chinese Holstein Bulls: A Preliminary Investigation

The current study conducted a preliminary investigation of genetic correlations in Chinese Holstein bulls to improve their semen quantity and quality by indirect selection of conformation traits. The results of seven semen traits and nine conformation traits showed that the heritability estimates of semen traits ranged from 0.24 (post-thaw motility) to 0.63 (volume per ejaculation), while the conformation traits ranged from 0.29 (pin width) to 0.80 (withers height). Phenotypic correlation between scrotal circumference (SC) and semen concentration per ejaculation (SCPE), SC and total number of sperm per ejaculation (TNS), and SC and total number of motile sperm per ejaculation (TNMS) was 0.22, 0.25, and 0.24, respectively. Genetic correlation between SC and SCPE, SC and TNS, and SC and TNMS was 0.41, 0.40, and 0.38, respectively. To summarize, moderate or high heritability of semen traits indicated that genetic improvement of semen quality by selection is feasible, where SC could be a useful trait for indirect selection or as correlated information to improve semen quantity and production.