The purpose of raising sows is to obtain more piglets, and there are two main indicators for measuring the reproductive performance of sows: the number of weaned piglets per year and the reproductive use of sows per sow.
Factors affecting the reproductive performance of sows include genetics, nutrition, disease, environment, and management. In recent years, with the rapid development of nutrition technology, research on improving the reproductive performance of sows through nutrition regulation has achieved initial results. Studies at home and abroad have found that almost all vitamins have a greater impact on the reproductive performance of breeding pigs. The main vitamins that affect the reproductive performance of sows are as follows:
1 Vitamin E
Vitamin E is closely related to reproductive function, can promote the production of thyrotropin (TH) and adrenocorticotropic hormone (ACTH) and gonadotropin, enhance ovarian function, increase follicles to increase luteal cells, and supplement vitamin E in sow diets. Not only can improve the conception rate, reduce fetal death, increase the litter size, but also enhance the anti-stress ability of piglets, reduce the death of piglets before weaning, shorten the weaning to estrus interval, and improve the quality of boar semen. Studies have shown that the number of litters and the number of litters in the sows fed high levels of vitamin E are higher, and the incidence of mastitis, metritis, and milkless syndrome (MMA) is lower. When the sow lacks vitamin E, the ovarian function declines, the sexual cycle is abnormal, it cannot be fertilized, the embryo is abnormally developed or the stillbirth occurs.
2 folic acid
It plays an important role in maintaining the reproductive performance of sows and promoting the early development of the fetus. Its main function is the involvement of coenzymes in various enzyme systems in the synthesis of purines, so it is important for the synthesis of DNA and RNA. In terms of maintaining the stable reproductive function of the sows, the litter size can be increased, the lactation can be maintained, and lactation disorders can be prevented.
3 β-Carotene
Supplementation of beta-carotene in sow feed will improve litter size, correct sow estrus and ovulation delay, and increase embryo survival. Beta-carotene is also associated with the synthesis of lutein, which is insufficient to cause termination of pregnancy. Recent studies have also found that the addition of beta-carotene to boar feed can promote testicular development and improve semen quality. Vitamin A and carotene are easily destroyed by oxidation, especially in the case of moist heat and contact with trace elements and rancid fat.
4 Vitamin A
Properly increasing the amount of vitamin A added to the diet can increase litter size and number of weaned piglets (Antipas, 2003). When the sow lacks vitamin A, the conception rate decreases, the estrus is abnormal, dystocia, miscarriage, stillbirth, weak fetus, deformed fetus and placenta are not enough; piglets blink and limb paralysis are prone to pneumonia, diarrhea, etc.; young sows have delayed estrus, affecting Ovarian development, high embryo mortality.
5 Biotin
The main function is to maintain the health of the sow's hooves and prevent shins, lameness and sputum. At the same time, it can promote fetal growth and development, reduce fetal death and promote lactation, increase ovulation rate and conception rate of sows, and shorten the weaning to estrus interval. If the biotin content in the diet is less than 330ug, it will result in an increase in stillbirth and a poor growth and development of suckling piglets due to insufficient breast milk. The study found that supplementation with biotin can increase the length of the sow's uterine horn by 20%, which in turn increases the space occupied by the fetus in the uterus, which is of great significance for the growth and survival of the fetus.
Studies have shown that 300mg biotin is added to the full-price feed per ton of sows, and the average number of weaned pigs at 21 days is significantly higher than that of the un-biotin control group. The addition of biotin to the sow diet can prevent the sow from cracking in the winter, significantly reducing the incidence of foot problems in the herd and lameness.
6 Vitamin C
It plays an important role in various redox reactions in living cells, participates in the synthesis of sterols in the adrenal cortex, helps relieve stress, and eliminates the adverse effects of high temperature on semen quality. After the boar is fed with vitamin C, the sperm quality is improved, and the sow has an increased conception rate. Especially in the summer high temperature or sow before and after childbirth to withstand environmental or physiological stress, and vitamin C has a strong anti-stress effect, can improve the sow reproductive performance by relieving stress. Breast milk is the only source of vitamin C in piglets before 1 week of age. Supplementation of vitamin C to sows during pregnancy and lactation reduces the mortality of piglets before weaning.
7 Vitamin B2 (riboflavin)
Studies have shown that feeding 4 mg of riboflavin for 4-7 days after sow breeding can increase the number of live embryos, embryo survival rate, litter size and litter size. Tilton (1991) confirmed that supplementation of 90-100 mg/d riboflavin to sows during early pregnancy significantly increased sow littering rates.
8 Vitamin K
Adding 100mg/kg vitamin K3 to the diet of pregnant sows increased the litter size by 5.66%. Adding 100mg/kg vitamin K3 to the diet of lactating sows can increase the weight gain of piglets by 7.78% and increase the survival rate of piglets by 3.81%.
9 Vitamin B6
Pregnancy sow diet plus 15mg/kg vitamin B6 (control group 1mg/kg) can reduce the interval from weaning to estrus by 1.1 days.
10 Niacin
The addition of 33 mg/kg niacin to the sow's gestational and lactation diets reduced the incidence of sow's metritis-mastitis-milk-free syndrome by 30%.
In summary, vitamins play an important role in sow production and reproduction. Lack of vitamins can cause sows to produce various diseases. Therefore, the vitamin needs of sows must be met during the production process.
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