Genetic and Non-genetic Factors Influencing Semen Production Traits in Dairy Bulls

Abstract

Background: The choice of superior herd sires is essential for genetic improvement in dairy cattle, with sperm quality serving as a key factor. Bull semen’s superior qualities are essential for accelerating genetic improvement through AI. These characteristics are affected by several factors, including the environment, management techniques, physiological condition and hereditary factors. This study involved in evaluating genetic and non-genetic factors influencing seminal attributes. Methods: Data on 1,85,413 ejaculates from nine genetic groups viz. Jersey, Holstein Friesian, crossbred Jersey, crossbred Holstein Friesian, Bargur, Kangayam, Pulikulam, Umblachery and Red Sindhi were collected from four frozen semen stations of Tamil Nadu State. Semen production data viz. ejaculate volume (mL), spermatozoa concentration (million per mL), initial motility (percentage), post-thaw motility (percentage), total initial motile spermatozoa and total post-thaw motile spermatozoa were also examined for various genetic and non-genetic factors affecting them using linear mixed model with repeated measures. Result: The overall estimated marginal means for Volume of ejaculate, Concentration of spermatozoa, Initial motility, Total initial motile spermatozoa per ejaculate, Total doses per ejaculate, Post-thaw motility and Total post-thaw motile spermatozoa per ejaculate were 3.11 ± 0.11 (mL), 963 ± 30.60 (106/mL), 79.50 ± 1.29 (per cent), 1847 ± 118 (106), 151.00 ± 7.20, 51.00 ± 0.42 (per cent) and 1535 ± 80.20 (106) respectively.The effect of all genetic and non-genetic factors (farms, ejaculates, period, seasons, age) were observed to be significantly influencing the seminal traits considered in the study. However, the estimated marginal means of each trait displayed varied ranges of mean against non-genetic factors.