The secret to mastering the best breeding time for sows

In order to improve the conception rate of sows and increase the number of embryos, not only boars are required to provide high-quality sperm, sows are required to produce more fertilized eggs, but also to allow boars and sows to mate in an appropriate time, so that most or all of the eggs have a chance to be fertilized. This is the key to determine the conception rate and the number of babies to be born. For this reason, we should first grasp the law of oestrus and ovulation in sows, and then consider comprehensively according to the time for the bisexual germ cells of spermatozoa and eggs to maintain the ability of fertilization in the reproductive tract of sows.

(1) the regularity of oestrus of sows after delivery

Sows usually have three times of estrus in a short time after delivery: the first time occurs 2-7 days after delivery, the estrus symptoms are not obvious and cannot ovulate normally, which is an infertile estrus; the second estrus occurs at 22-32 days after delivery; the symptoms are not obvious, but if mating can conceive, it will not affect lactation and litter performance, so it is a breeding opportunity that should be used; the third time is 3-7 days after weaning. According to statistics, under normal feeding and management conditions, 85% of sows are in estrus within 7 days after 35-day-old weaning, which is a breeding opportunity that must be grasped.

(2) ovulation regularity of estrus sows

After the sow reaches sexual maturity, the sexual cycle occurs regularly. in the sexual cycle, the estrus is the peak of the sexual cycle. during this period, sows accept the climbing and mating of boars, and it is also the duration of ovulation in sows. Sows accept mating or insemination during this period, so it is an important period for sows to accept boar crawling. As for other signs of estrus, they are auxiliary symptoms of estrus. When the estrus sow accepts the boar and the duration of the climb is related to the type, breed, age, feeding and management conditions of the pig.

(3) timely breeding

It was observed that the longest survival time of sperm in the reproductive tract of sows was 42 hours, but the time of sperm with fertilization ability was only 25 hours and 30 hours, and the sperm had fertilization ability after 2-4 hours in the reproductive tract of sows. This is commonly known as "sperm capacitation". Only the sperm that has acquired the ability to fertilize can combine with the egg.

The egg is excreted from the ovary and enters the enlarged part of the fallopian tube through the umbrella, where the sperm and the egg meet before they can be fertilized. The time for the egg to pass through this part of the fallopian tube, that is, the time for the egg to maintain fertilization ability, is 8 to 10 hours, and the longest is about 15 hours. If the egg is not fertilized in the enlarged part of the fallopian tube, it continues to move along the fallopian tube to the uterine horn, and the egg will gradually age and be wrapped in fallopian tube secretions, hindering the entry of sperm and losing the ability to fertilize.

The experiment shows that the time for the sperm to reach the fallopian tube of sows is very short, and after capacitation, the time of fertilization ability is much longer than that of eggs. Therefore, it is necessary to inseminate or inseminate sows before ovulation, especially a few hours before the peak stage of ovulation, that is, 2-3 hours before ovulation or 12-24 hours after the onset of estrus, so that sperm can wait for the arrival of eggs.

As there are differences in different varieties, ages and individual ovulation time, it should be mastered flexibly when determining the mating time. From the point of view of breeds, Chinese local pig breeds have a longer duration of estrus and ovulate later, and can be mated on the 3rd-4th day of estrus, while the introduced breeds have shorter duration of estrus and ovulate earlier, and can be mated on the second day of estrus. Hybrid pigs can be mated in the afternoon or 3rd day after estrus. In terms of age, the oestrus of young sows was shorter than that of aged sows, while that of local breeds in China was the opposite. Thus it can be seen that the breeding experience of "old mating early, small mating late, not old many in the middle" is only in line with the law of oestrus and ovulation of pig breeds in our country.

From the estrus performance, the sow mental state from restlessness to daze (hands pressing waist and buttocks do not move), vulva from red and swollen to pale wrinkles, mucus from watery to sticky, it means that it has reached the adaptation period. When the vulva mucosa is dry and refuses to mate, it means that the adaptation time has passed.

At present, it is best to adopt the method of insemination or insemination twice during estrus, so that during ovulation, there will always be energetic sperm waiting for the egg to arrive at the fertilization site. The exact time of two insemination or insemination in one estrus varies slightly due to the breed type, age and feeding and management conditions of pigs. It is generally believed that the conception rate and litter performance of estrus sows are better when they are mated for the first time at 8-12 h after boar climbing and the second mating at 12 h interval.