Effects of different estrum on sows’reproductive performance

Primiparous sows’ reproductive performance in three years including the litter size， number born alive，death litter size， number of mummies， number of fetal malformation and number of weak piglets were collected， and the effect of different estrum on sows’reproductive performance were analyzed. Compared to the sows of the primary mating in the second estrum， the differences of the average litter size were not obvious among the sows of the primary mating in the third and fourth estrum， the survival number was increased remarkably， primary mating breeding rate has a remarkable increase， less differences in the average dead number， obvious reduction of the mummy number and less differences in the weak piglets number. Consequently， with postponing entering of the estrum properly and increasing the conditions of the estrum， the survival piglets number can be improved，the average mummy number can be lowered，which improved the breeding rate of the sows.