How to promote estrus in reserve sows

Back-up sows are usually raised in small pens (4 to 8 in each pen). After the age of 5.5 months, they begin to come into contact with boars, exercise for sows, and exchange boars raised in stalls (preferably once a week). With high-quality feed (rich in vitamin E, vitamin A, vitamin D, choline and necessary trace elements and amino acids, etc.), it is better to take short-term supplementary feeding combined with changing materials to promote estrus.