How to Increase the Number of Live Piglets Born per Litter in Sows? A Detailed Guide to Practical Methods

The number of piglets born per litter in sows is an important indicator for measuring sow reproductive performance. It reflects the production management level of the entire pig farm and has a direct impact on the economic benefits of pig farming.

Depending on the target of interest, the number of piglets born per litter in sows can be classified as follows: total number born, which refers to the total piglets born, including stillborn and mummified fetuses; number born alive, which refers to all live piglets excluding mummified fetuses and stillborns. The number of viable piglets refers to the number of live piglets excluding weak piglets.

To ensure the production performance of a pig farm, efforts must be made to increase the number of live piglets per litter in sows

1. Increase the number of ova released and egg quality in sows

An increase in the number of ova released during estrus in sows, along with good egg quality, is very important for increasing the number of live piglets born per litter. To increase the number of ova released and egg quality in sows, short-term flushing can be applied before mating.

Production practice shows that increasing the feed intake of sows 1-2 weeks before mating and appropriately raising the nutritional level of the diet can increase the number of ova released and the number of piglets born in sows. For multiparous sows, efforts can be made to increase feed intake from weaning to estrus.

However, attention must be paid to the nutrition in the diet. Since hormones secreted by the intestinal tract after weaning in sows can interfere with the metabolism of nutrients, feeding a diet with a high protein level has little effect on the number and quality of ova, while feeding a feed with a higher fiber content can promote greater feed intake in sows and also eliminate hormones secreted by the intestinal tract.

2. Improve the fertilization rate

To improve the fertilization rate, the first step is to improve the semen quality of breeding boars.

To improve the semen quality of breeding boars, their nutrition should be strengthened, with attention to the supply of protein, vitamins, and trace elements in the diet. For example, increasing the content of selenium and VE in the diet of breeding boars can significantly improve semen quality, because selenium and VE have antioxidant effects and play a major role in improving sperm motility and ensuring sperm quality.

The protein level in the diet greatly helps improve semen quality and quantity, especially for boars with a high semen collection frequency. Therefore, during the breeding period, breeding boars can be fed 1-2 eggs per day. To improve the conception rate of sows after mating, on the one hand, the quality of ova should be improved; on the other hand, mating should be done at the right time, the optimal mating time should be grasped, and scientific mating methods should be adopted to improve the fertilization rate.

3. Improve the embryo survival rate

In the early stage of gestation in sows, the fertilized eggs are in a free state, and embryo death and miscarriage are likely to occur during implantation, reducing the number of live piglets born per litter. Generally, in the early stage of gestation, excessive nutrient intake by sows can cause early embryo death.

Therefore, within 2 weeks after mating, the nutritional level of the diet needs to be controlled, or the feeding amount should be reduced, to improve the embryo survival rate. However, if the feed intake of sows in early gestation is insufficient, or nutrient intake is low and unbalanced, it will cause hunger in sows, lead to malnutrition, and affect embryo implantation.

In the early stage of gestation, the feed only needs to maintain the sow's own nutritional requirements, but attention should be paid to the amount of vitamins and trace elements in the diet. For example, VA is closely related to the reproductive performance of sows. VA participates in ovarian development, follicle maturation, corpus luteum formation, functional perfection of oviduct epithelial cells, and embryo development in sows. Therefore, increasing the VA level in the diet of breeding sows can effectively reduce embryo death and is extremely beneficial for increasing the number of live piglets born per litter.

In addition, early embryo development requires an increased amount of folic acid to maintain rapid embryo differentiation, thereby improving the survival rate of embryos and fetuses and further increasing the number of live piglets born per litter in sows. Feed quality should be ensured, and feeding moldy feed is strictly prohibited, because mycotoxins can cause miscarriage in sows or cause fetal deformities.

In addition to reasonable feeding, improving the embryo survival rate also requires strengthening daily management. The purpose is to prevent stress responses in sows. Therefore, the ambient temperature of the sow house should be well controlled to prevent heat stress in sows. When sows experience heat stress, embryo development is hindered, the number of stillborns increases, and the number of live piglets born per litter decreases.

In addition, other types of stress in sows should also be avoided, such as feed change stress and environmental stress.

4. Increase uterine capacity
 

The uterine capacity of sows is also a major factor affecting the number of live piglets born per litter. If the number of ova released by sows, after subtracting the number of failed fertilizations and embryo deaths, still exceeds the uterine capacity, the growth and development of embryos will be restricted.

Uterine capacity is determined by genetic factors, but it is also affected by interactions among the uterus, placenta, and fetus. These all affect embryo survival during gestation. Uterine blood flow and uterine proteins are the two main uterine factors affecting uterine capacity. Placental size and the efficiency of nutrient transfer are placental factors affecting uterine capacity. Fetal red blood cell production and fetal nutrition are fetal factors affecting uterine capacity. As the number of fetuses increases, these factors exhibit compensatory behavior.

In addition, constipation in sows increases intestinal pressure on the uterus, affecting uterine blood flow and blood flow distribution, especially in the late stage of gestation, when it is more serious. The occurrence of embryo death and dystocia can lead to a reduction in the number of live piglets born per litter. Therefore, sows should be prevented from constipation during gestation. This can be improved by increasing the fiber level in the diet, thereby improving fetal survival rate.

5. Do a good job in farrowing assistance for sows

Do a good job in farrowing assistance for sows to reduce the occurrence of stillbirths during farrowing. If the farrowing process of sows is prolonged, it will cause fetal suffocation and death, thereby reducing the number of piglets born per litter.

There are many causes of dystocia, including large fetuses and weak labor in sows. Multiple aspects should be addressed to prevent dystocia in sows. In the late stage of gestation, excessive fetal size should be avoided during gestation boosting, and appropriate nutrition and exercise for sows should also be ensured to guarantee strong uterine contractions during farrowing.

During farrowing, sows should be allowed to give birth on their own as much as possible, and the farrowing assistants should observe carefully. If dystocia is found, assistance should be provided promptly using scientific midwifery methods. After the piglets are delivered, nursing care should be done well. If piglets appear to be stillborn, they should be rescued promptly to reduce the number of stillbirths.