INFLUENCE OF THE SEXUAL MOTIVATION OF THE BOAR ON THE SEXUAL PARTNER PREFERENCES OF ESTROUS GILTS

This study examined whether the sexual partner preferences of oestrous gilts are related to differences in the level of sexual motivation of their male partners. Twelve 1-year-old boars were ranked on the basis of the total number of copulations achieved and the average interval to first mount in three weekly 15-min mating tests. The four top-ranking and four bottom-ranking boars were assigned to form test pairs, each comprising a high motivation (H) and a low motivation (L) male. The relative preferences of 15-17 ovariectomised oestrous gilts for boars in each of the four pairs were individually studied in 5-min T-maze tests. Data recorded included the time that the gilt spent within 0.5 m of each of the two boars as well as bouts of courting behaviours exhibited by the boars. A sexual partner preference was found within only two of the four boar pairs. In one case the gilts spent more time within 0.5 m of the H boar (P < 0.01 ) while the L boar of the other pair was preferred (P < 0.01 ). Differences between boars in levels of courting behaviour in the T-maze tests within these pairs corresponded to boar preferences. However, a difference (P < 0.01 ) in the level of courting behaviour of the boars in a third pair was not accompanied by a preference for the more active male. No boar preferences nor difference in level of courting behaviour of the boars were observed in the fourth pair. It was concluded that boars may differ in their ability to attract oestrous gilts. However, attraction for boars does not appear to be primarily determined by their level of sexual motivation.