Sexual Behaviors of Boars under Multi-Sire Mating in Summer and Fall

Abstract

The experiment was conducted at a commercial swine farm to study the sexual behaviors of boars under natural light in summer and fall. In total, thirtytwo sows and 6 boars were used. Six boars were equally put in the two sire groups, and 32 sows were eqully divided into the 4 sow groups. The sexual behaviors of boars toward a herd. of sows in a mating pen were recorded continuously for 48h with an infrared camera connected to a time lapse video recorder. Two observations per sire group were carried out, the first in July and the second in October, 1989, using different sow groups. The sexual activity patterns of boars under multi-sire mating were similar between the seasons, irrespective of the fact that the day length was about 3 hours longer in summer than in fall, and the average, maximum and minimum temperatures were 9.4°C, 10.0°C and 8.9°C higher in summer than in fall. Diurnal patterns of ambient temperatures were, however, quite similar between the seasons. Sexual activities reached a peak at around 06:30 when the ambient temperature started to rise in the both seasons. These results suggest that the sexual activities of boars may correspond with the diurnal pattern of ambient temperatures.