Influence of the number of artificial inseminations and the duration of post-weaning estrus on the pregnancy rate of gilts

Abstract

The post-weaning estrus lenght and pregnancy rate in 106 primiparous under two different reproductive management and 278 pluriparous sows were studied.Oestrus detection was performed twice a day in the presence of a boar beginning at the day of weaning until service. Al with fresh semen of high quality was done in a convencional way. Two groups of AI frequency were used with the purpose of increase gestation rate mainly in primiparous sows. In Group "A" A.I. dosis were given 12,24 and 36hrs. after estrus detection; in Group "B" an adiccional AI dosis was performed at 48hrs. after onset of heat. Pregnancy diagnosis were done by ultrasound 28·30 days after insemination. The second group increased significativally the pregnancy percentage in primiparous (42.86 vs 78%) and pluliparous sows (73 vs 90%). The possibles causes of post-weaning estrus prolongation and the effects of reproductive management changes was discussed.