Detailed Explanation of Key Points in the Feeding and Management Techniques for Open (Non-pregnant) Sows

An open sow refers to a sow that has finished giving birth to piglets and then entered the lactation period; after the piglets are weaned, the sow enters the open period, and this period lasts until the next mating. The feeding and management techniques for open sows are as follows.

Key Management Points

To prompt the sow to come into heat as soon as possible and be mated, so that she conceives.

Short-term flushing to promote estrus and ovulation

1. Under normal feeding and management conditions, a lactating sow should have a body condition of 7-8 tenths fat when the piglets are weaned. After weaning, she should be able to come into heat again and be mated within 7-10 days, starting the next reproductive cycle. Some people pay very little attention to open sows, mistakenly believing that since an open sow is neither pregnant nor nursing piglets, feeding her casually is enough. In fact, this is not the case. Many experiments have proven that short-term flushing of open sows before mating has a good effect on promoting estrus and ovulation and making conception easier.

2. In the few days before the piglets are weaned, the sow can still secrete a considerable amount of milk (especially sows weaned early). To prevent the sow from developing mastitis after weaning, the amount of compound feed should be reduced for 3 days before and after weaning, and some green and coarse feed should be given to satisfy hunger, prompting the sow to dry off as quickly as possible. After the weaned sow has dried off, since her burden is reduced and her appetite is strong, supplying more nutrient-rich feed and ensuring adequate rest can help the sow quickly recover her strength. At this time, the nutritional level and feeding amount of the daily ration should be the same as in late gestation. If animal-based feed and high-quality green and succulent feed can be added, so much the better, as this can promote estrus and ovulation in open sows and lay the material foundation for improving the conception rate and litter size.

3. Sows that nursed many piglets during lactation, or sows with a longer lactation period, are often weak. At this time, feeding should be strengthened as soon as possible to help them recover their strength and maintain a body condition of 7-8 tenths fat. This is the basic condition for ensuring that sows come into heat in a timely manner after weaning.

4. Open sows likewise require environmental conditions such as dryness, cleanliness, suitable temperature and humidity, and fresh air. If an open sow cannot obtain good feeding and management conditions, it will affect estrus, ovulation, and conception after mating.

Methods for Controlling Normal Estrus in Sows

1. Boar induction method: Regularly use a teaser boar to chase and mount open sows that are not in heat. Through the pheromone odor secreted by the boar and contact stimulation, the nervous reflex action can cause the pituitary gland to secrete follicle-stimulating hormone, prompting the sow to come into heat and ovulate. This method is simple, easy, and effective. Another simple and effective method is to play an audio recording of a boar's courtship calls. By using the conditioned reflex effect and conducting continuous teasing, this biological simulation approach also works very well.

2. Grouping and pen merging: Merge open sows that are not in heat into pens with sows that are in heat. Through stimulation from behaviors such as mounting, promote estrus and ovulation in the open sows.

3. Udder massage: The method is to use the palm of the hand to perform superficial massage after feeding every morning, about 10 minutes per udder. After a few days, once the sow shows signs of estrus, perform superficial and deep udder massage for 5 minutes each every day. On the day of mating, perform deep massage for about 10 minutes.

4. Increase exercise: Driving sows that are not in heat to exercise can promote metabolism and improve body condition. Driving exercise allows them to receive sunlight and breathe fresh air, prompting estrus and ovulation. If it can be combined with grazing, the effect will be even better.

5. Litter merging: After the piglets born to sows with small litters and poor milk production have finished their colostrum, foster all of them to other sows that farrowed at the same time for nursing. In this way, the sow can dry off earlier, come into heat and be mated earlier for use, increasing the number of litters per year and the number of piglets born per year.