Genetic and environmental effects on semen quality of Austrian Simmental bulls

Semen production data from an Austrian AI centre collected between 2000 and 2004 were analysed. In total, 12,746 ejaculates from 301 AI bulls were examined considering different effects on ejaculate volume, sperm concentration, percentage of viable spermatozoa in the ejaculate, total spermatozoa per ejaculate and motility. The model included the fixed effects of age of bull, collection interval, number of collections on collection day, bull handler, semen collector, year and month of collection, and a random additive genetic component. Age of bull, collection interval, number of collection on collection day, and year and month significantly affected most semen quality traits. The collection team (bull handler and semen collector) had relevant effects on semen traits. All semen production traits were moderately heritable and correlated. Heritabilities for volume, concentration, percentage of viable spermatozoa, total spermatozoa and motility were 0.18, 0.14, 0.10, 0.22 and 0.04, respectively. Correlations between estimated breeding values of sperm quality traits and routinely estimated breeding values for male fertility were low and ranged from 0.10 to 0.20.