Genetic evaluation of semen traits in Holstein-Friesian purebred, Holstein-Friesian crossbred and indigenous bulls under hot and semi-arid conditions of India

Genetic parameters of semen production traits were evaluated in Holstein-Friesian (HF) purebred, HF crossbred and indigenous bulls using Bayesian univariate and bivariate models. Data from 486 bulls on 164,962 ejaculates collected from Bharatiya Agro Industries Foundation (BAIF) was utilized for this study. Six semen production traits viz. ejaculate volume (EV-ml), sperm concentration (SC-109/ml), initial sperm motility (ISM-%), post -thaw motility (PTM-%), total number of spermatozoa per ejaculate (TNS-109/ejaculate) and the theoretical number of semen doses (TNSD) were included in the analysis. Gibbs sampling was done to implement a Bayesian framework where 200,000 and 500,000 Gibbs samples were obtained for univariate and bivariate analyses respectively. In general, the estimates of the means for semen production traits were lower in indigenous bulls except for ISM. Heritability estimates ranged between 0.023 (ISM) to 0.340 (SC) in HF purebreds, 0.011 (PTM) to 0.076 (EV) in HF crossbreds and 0.025 (ISM) to 0.153 (TNS) in indigenous bulls. Repeatability estimates ranged between 0.030 (PTM) to 0.412 (SC) in HF purebreds, 0.012 (PTM) to 0.391 (SC) in HF crossbreds and 0.067 (ISM) to 0.333 (EV) in indigenous bulls. Highly negative genetic correlations were obtained between EV and SC whereas they were highly positive between ISM and PTM. Precise genetic parameter estimates could be obtained for the semen production traits using a Bayesian framework which will further facilitate in the improvement of semen traits and bull fertility.

Automated summary

Genetic parameters of semen production traits in Holstein-Friesian (HF) purebred, HF crossbred, and indigenous bulls were evaluated using Bayesian univariate and bivariate models. The study found that indigenous bulls had lower mean values for semen production traits, except for initial sperm motility. Heritability and repeatability estimates varied among different breeds and traits. There was a negative genetic correlation between ejaculate volume (EV) and sperm concentration (SC), while a positive genetic correlation was observed between initial sperm motility (ISM) and post-thaw motility (PTM). The Bayesian framework provided precise genetic parameter estimates that can contribute to the improvement of semen traits and bull fertility.