Genetic parameters for semen traits in AI boars estimated from data on individual ejaculates.

Semen volume, sperm concentration, percentage progressive motility, percentage of abnormal spermatozoa and total number of sperms from 215 830 ejaculates were analysed. The ejaculates were collected between 2000 and 2005 and originated from 3675 boars of different breeds and crossbred combinations from 23 AI centres of the Czech Republic. Genetic parameters were estimated using multiple- and single-trait animal models. Factors included in the models were: breed or crossbred combination, year-month, age class of the boar, interval between subsequent semen collections, joint effect of AI centre and year, permanent environment and additive genetic effect of the boar. The estimated heritabilities for semen volume and sperm concentration were approximately 0.20, whereas the estimates were somewhat lower for motility, percentage of abnormal sperm and total number of sperms. High negative genetic correlations were estimated between semen volume and sperm concentration (-0.68 for dam breeds, -0.69 for sire breeds) and between motility and percentage of abnormal sperm (-0.93 for dam breeds and -0.59 for sire breeds). The correlations between both semen volume or sperm concentration and motility or percentage of abnormal sperm were mostly small and negligible. Repeatabilities of 0.43-0.46, 0.37-0.38, 0.29-0.35, 0.42-0.50 and 0.29-0.30 were estimated for semen volume, sperm concentration, motility, percentage of abnormal sperm and the total number of sperms, respectively. On the basis of the estimated genetic parameters presented here, effective selection on sperm characteristics, especially for volume and concentration, should be possible using an animal model.