EFFECT OF SEASONAL FACTORS ON THE EJACULATE PROPERTIES OF CROSSBRED DUROC X PIETRAIN AND PIETRAIN X DUROC BOARS AS WELL AS PUREBRED DUROC AND PIETRAIN BOARS

The experimental material consisted of 12,285 ejaculates obtained from 93 boars, including 18 Duroc boars, 30 Pietrain boars, 24 female Duroc x male Pietrain crossbreds and 21 female Pietrain x male Duroc crossbreds. The boars were utilised for it least 6 months and qualified for insemination from January 1, 1992 to December 31, 2007. Each ejaculate was assessed using standard methods for the following physical traits: volume, sperm concentration, spermatozoon motility, total number of spermatozoa, and number of insemination doses per ejaculate. The data obtained were classified into 12 sub-groups consisting of ejaculates collected in successive months. Ejaculates collected in the summer months had less spermatozoa than in the autumn and winter period. Ejaculates collected in the summer (mainly in July) yielded the least amount of insemination doses. Ejaculates of both types of crossbreds were characterised by greater spermatozoon motility compared with purebred boars, irrespective of the month of ejaculate collection.