Reasons and Solutions for Sows Not Coming into Estrus After Weaning

Under normal circumstances, sows will come into estrus about one week after weaning. But quite a few farmers report that ten to twenty days after weaningthey still do not come into estrus. Why is that? What should be done?

What should be done if a sow does not come into estrus after weaning?

First, feeding should be strengthened, choosing a complete feed specially designed for lactating sows, and feeding 3-4 times a day to ensure that weight loss at weaning is not excessive; second, ventilation in the pig house must be ensured, and cooling is needed in summer. In addition, for sows that do not come into estrus, an appropriate dose of diethylstilbestrol, anterior pituitary gonadotropin, cloprostenol, etc. can also be injected intramuscularly.

What are the reasons for sows not coming into estrus after weaning?

1. Gilts bred too early for their first mating

For gilts that have just entered puberty, although their reproductive organs already have normal reproductive function, breeding and conceiving gilts too early will not only lead to fewer piglets in the first litter, low birth weight and low weaning weight of piglets, and a low survival rate, but will also affect the sow's own weight gain.

2. Excessive weight loss of the sow at weaning

Under normal circumstances, after going through a lactation period, a sow will lose weight to varying degrees, with the weight loss ratio generally about 25%, and this does not affect normal estrus and mating after weaning. However, if the diet lacks nutrition, milk yield is high, and the sow is nursing too many piglets, the sow will become abnormally thin at weaning, and the extent of weight loss will be relatively large; if it exceeds 60 jin, then estrus and mating after weaning will be noticeably delayed.

3. Seasonal influence

Sows are polyestrous livestock and can come into estrus and be mated year-round? But in the hot summer season (June—September), in the 7 days after piglets are weaned, the estrus rate of sows is 20% lower than in other seasons, and this is even more obvious in first-parity sows.

4. Sows being too fat

Some sows have low milk yield during lactation and nurse few piglets; some farms also feed high-protein and high-energy diets, with unrestricted feeding for a long time, so that body weight does not decrease at weaning and a large amount of fat is deposited in the body, causing the sow to become excessively obese and leading to arrested follicular development, so that the sow cannot come into estrus and be mated normally and naturally.

5. Endocrine abnormalities

During farrowing, the sow may suffer birth canal injury or contamination, retained placenta or retained fetal tissues and fragments, retention of lochia when the uterus is atonic, unclean surgery during dystocia, incomplete disinfection during artificial insemination, or the boar's reproductive organs or semen containing inflammatory secretions during mating; or the sow may suffer from brucellosis or inflammation of the reproductive system caused by other microbial infections.

6. Unscientific feed use

Some farms do not use feed specially designed for sows, but instead choose feed for growing-finishing pigs to raise sows. Although the feeding cost is somewhat lower, feeding this way for a slightly longer time may cause great harm.