489. Random regressions for modelling semen production traits in HF purebred and crossbred bulls using Bayesian framework

Abstract

Semen traits including ejaculate volume (EV, ml), sperm concentration (SC, 109/ml), initial sperm motility (ISM, %) and post-thaw motility (PTM, %) were analysed using random regression models. Data pertaining to 105,321 ejaculates from 297 Holstein-Friesian (HF) purebred and crossbred bulls collected from Bharatiya Agro Industries Foundation were utilized. 200,000 Gibbs samples were generated with a burn-in of 20,000 and thinning interval of 50 in a Bayesian framework. Legendre Polynomials with orders of fit up to five for additive and permanent environmental effects were used. Heritability estimates ranged from 0.2 to 0.5 for EV and 0.35 to 0.5 for SC in purebreds while it ranged from 0.05 to 0.45 for EV and 0.2 to 0.7 for SC in crossbreds. Estimates were very low for motility traits in both purebred and crossbred bulls. Random regression models in a Bayesian framework were useful for obtaining solutions for mixed models even with large number of parameters.