What are the common reasons a sow does not come into heat?

Normally, a sow can come into heat at 7-8 months of age, but some sows are over 9 months old and weigh more than 140 kg and still do not come into heat, and some weaned sows do not come into heat for more than a month. When a sow does not come into heat, it cannot be mated normally, which seriously affects breeding profits. So what are the reasons a sow does not come into heat? Let's find out.

1. Reasons for not coming into heat

The reasons a sow does not come into heat are mostly improper feeding and management, poor growth, and disease. Especially in rural free-range farming, many farmers manage feeding improperly, which often makes sows too fat or too thin, leading to delayed estrus. In addition, too high or too low temperature and humidity in the pig house can also affect a sow's estrus; high temperatures inhibit the development of the sow's gonads, and for replacement gilts that have already reached the appropriate age and weight for estrus, failure to go through boar induction can also cause them not to come into heat.

2. Methods to induce estrus

There are many methods to induce estrus in sows. The common one is boar induction: house a sow that does not come into heat in the same pen as a boar, let the boar chase and mount her, and the boar's odor will stimulate the sow's pituitary gland, promote gonadal development, and bring on estrus. Playing a recording of a boar's courtship calls can also have a stimulating effect. You can also house sows in heat together with sows not in heat, which will also stimulate estrus, or appropriately increase the sow's exercise by putting her out to pasture, creating a suitable environment to promote estrus in the sow.

3. Medication

In addition to the estrus induction methods above, medication can also be used. You can inject a sow with 5 ml of pregnant mare serum gonadotropin; for a sow weighing 75-100 kg, an intramuscular injection of 1000 units of chorionic gonadotropin can promote estrus and ovulation, with good results. Traditional Chinese medicine can also promote estrus: decoct 100 g of dodder seed in 250 ml of water, add it to the feed, and feed 1-2 times a day for 2-3 consecutive days, or decoct Chinese medicinal herbs such as ricepaperplant pith, papaya, and magnolia bark in water and feed the liquid.

4. Principles of handling

For a sow that does not come into heat, the first step is to improve its feeding and management, then use various prevention and treatment methods according to the reason it does not come into heat, so as to achieve good results. For sows that still do not come into heat after measures are taken, cull them promptly, or sell them as fattening pigs for market, to avoid further economic loss.

The above is an introduction to the reasons sows do not come into heat. We hope it helps you. To learn more related knowledge, please follow us.