Selection and retention of reserve sows by stages

Sows with the conditions for breeding generally go through three stages of selection: the first stage is that when the sows are 60 days old, they choose to grow rapidly and their nipples are arranged neatly, and there are more than 7 pairs of nipples for selection and retention. In the second stage, when the sows are mature and need to be mated (the local pigs are about 7 months old and the outbred pigs are about 8 months old), the reserve sows with fast growth, body length, stout limbs, non-sagging belly and thin body should be reserved for breeding. In the third stage, the sows with large litter number, good motherhood and strong lactation ability were selected for breeding after the sow gave birth to one child.