The aim of this study was evaluation of the quality of ejaculates of boars from Duroc and Pietrain breeds, and also crossbreeds born in different seasons. Materials used for the study were gathered during the process of breeding boars. There were 143 boars of breeds Duroc, Pietrain and their crossbreeds (Duroc x Pietrain and Pietrain x Duroc). The 20 442 of boars’ ejaculates were examined between 1997–2009 in the Małopolska Biotechnology Centre – Examinations Station of Boars in Czermin. Ejaculates were evaluated basing on: the volume of spermatozoid fractions, the percentage of progressive spermatozoids, spermatozoid concentration, total count of progressive spermatozoids and the total number of insemination doses obtained from one ejaculation. The parameters of examined ejaculates of boars races were analyzed statistically accordingly with their births seasons: spring (from 22nd March to 21st June), summer (from 22nd June to 21st of September), autumn (from 22nd September to 21st of December), winter (from 22nd December to 21st of March). The studies have shown the significance of impact that season of birth has on semen quality of boars and crossbreeds of evaluated races. The highest reproductive potential expressed as a number of insemination doses, was found in boars of Duroc and Pietrain breeds born in the summer. In case of crossbreeds, the best quality of sperm was found in males born in the winter season.

65-72