Mounting efficiencies, courtship behavior and mate preference of boars under multi-sire mating

Abstract

The mating behavior of boars toward a herd of sows in a mating pen was observed for 72 h at a commercial swine farm. Mating pens consisted of two to four purebred boars and eight crossbred sows. The observation was conducted on a total of four pens during summer 1987. Boars often mounted sows in estrus, but rarely attempted to mount anestrous sows. Total numbers of mounting events varied among boars in a pen. Mounting efficiencies (number of copulations per number of mounting events) were < 10% for most boars. There was a diurnal pattern in mounting events and the peak occurred at around 03.00 h. The observed courtship behavior of boars was broken down into seven categories: sniffing, head to head, nosing, following, chin resting, mounting and copulation. Sequence analysis was used to determine the pattern of the boars' preliminary courtship behavior before mating. The most frequently observed transition was from “head to head” to “nosing”, and “nosing” was located in the center of the courtship behavior pattern. It is likely that preferential mating exists between boars and sows in estrus.