2. timely breeding to improve the fertilization rate of ovulated eggs. Because of the differences of breeds, ages and individual ovulation time, we should be flexible in determining the breeding time. In terms of breeds, local pig breeds in China have short estrus duration, early ovulation and can be bred on the second day of estrus: imported breeds have long estrus duration and late ovulation, and can be bred on the third to fourth day of estrus; Hybrid pigs can be bred in the afternoon or the third day after estrus. From the age point of view, the estrus time of young sows introduced with pig breeds is shorter than that of old sows, while the local breeds in China are the opposite.
3. Improve the feeding management of pregnant sows and improve the embryo survival rate at the peak of embryo death. The first peak of embryo death is fertilized egg formation 9- 13d, which is the early stage of fertilized egg implantation, and it is easy to die due to various factors, with a mortality rate of about 50%. Therefore, all kinds of stress factors in this period should be reduced as much as possible, and sows should be kept in the original feeding mode within 3-4 weeks after mating. The second death peak is about the third week after pregnancy, that is, the third week after mating. This period is a period of organ differentiation, and the mortality rate is about 30%-40%. Attention should be paid to various stress and nutritional deficiency factors. During this period, the placenta stops growing and the fetus grows rapidly, which may be due to the fact that the placenta is not enough to support the development of the fetus, resulting in death, and the mortality rate is about 15%. Therefore, the nutrition of sows should be strengthened in the third trimester of pregnancy.
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