What are the key points for the feeding and management of replacement gilts?

The feeding and management of replacement gilts mainly involves the following aspects:

1. Body condition control and boar stimulation: Before reaching 60 kg, replacement gilts should be allowed to develop fully. From 60 kg until half a month before mating, feeding should be appropriately restricted to prevent them from becoming too fat, with about two kilograms of feed per day given in two feedings. Growing-finishing pig feed can be used for replacement gilts. When replacement gilts reach 160 days of age, it is best to drive the gilts into a pen with an adult boar for contact for 35 minutes each day. The pheromones secreted by the submandibular glands of adult boars help induce estrus in young gilts.

2. Short-term flushing: Fourteen days before mating, replacement gilts can be given enhanced feeding with free access to feed. In this way, the gilts can release about 2.5 more eggs, which undoubtedly plays an important role in increasing the litter size of first-parity gilts.

3. Mate gilts only when they have had at least two estrous cycles: The number of ovulations in gilts is related to the number of estrous cycles. Mating at first estrus results in a low litter size because of the low number of ovulations. Since first-parity gilts account for about 30% of the total sow herd, their reproductive performance directly has a major impact on the whole herd. An important purpose of boar stimulation to bring estrus on earlier is also to allow several more estrous cycles before mating. Some pig farms keep no records of the number of estrous cycles of the gilts they mate, which is undoubtedly an incorrect management practice.

4. Single mating, repeat mating and double mating: The best time for mating should be 10-26 hours after the estrous gilt allows the boar to mount. Single mating means using a boar to mate only once during a gilt's estrus. Although this can reduce the number of boars kept, because the optimal mating time for gilts is difficult to determine, single mating may reduce the conception rate and decrease litter size. Repeat mating means mating twice with the same boar during one estrous period, with an interval of 8-12 hours. In production practice, two boars of the same breed are also often used to mate twice at intervals. This method can keep relatively vigorous sperm present in the gilt's reproductive tract, increasing the chance of egg fertilization and thereby increasing the gilt's litter size. Double mating means that during one estrous period, two boars of the same breed or different breeds are used to mate the same gilt twice within a relatively short interval (10-15 minutes). This method can promote accelerated egg maturation, shorten ovulation time and increase the number of ovulations. However, because the interval between the two matings is short, this method often has disadvantages similar to single mating. Regarding mastery of the optimal mating time, there are four proverbs for reference: when the vulva is smeared with grass, insemination is just right; when the expression is dazed, insemination leads to conception; when standing still, it is exactly the time to mate; when the mucus becomes thick, that is precisely the moment. Song Youxue