To master the estrus law of sows and judge the best time for sow breeding, to be familiar with the common methods of sow breeding, and to evaluate different breeding methods.
According to the different conditions of pig farms, different methods can be used to identify estrus.
First, external observation and back pressure test methods.
For small pig farms without boar, external observation and back pressure test are mainly used to check the situation.
(A) mental state and behavior
Sows will have symptoms such as loss of appetite or even abandonment, singing, vulvar swelling and mental excitement before estrus. Sows entering the late estrus and estrus will have the behavior of climbing other sows in the same circle.
Sows in the early estrus have crawling behavior and are very sensitive to changes in the surrounding environment and sounds. As soon as there was any movement, they looked up and listened. Look in the direction of the sound. Walk back and forth in a circle or often stand at the door of the circle.
However, these behaviors can only represent that sows may enter estrus, and the sign that sows really enter estrus is the static reflex when they press their backs.
(2) Changes of vulva
Non-estrus sow, vulva is not swollen, labia is closed, and the middle seam is like a straight line.
1 ~ 2 days before estrus or earlier, the sow's vulva began to turn red, then the swelling increased, the vulva was bright red, and sometimes some mucus was discharged.
If the labia is loose and incomplete, the middle seam is bent or even everted, the color of the labia changes from bright red to dark red or dark red, and the amount of mucus is small and sticky.
Vaginal mucosa is slightly dark red.
And can be drawn into filaments between the index finger and thumb, so that it can be judged that the sow has entered the estrus peak.
(3) Back pressure test and stimulation of sensitive parts
Usually, sows who are not in estrus or before and after estrus will avoid people. If the sow does not avoid people's approach, or even approaches people actively, such as pressing the sow's back with hands or riding on it, standing still and supporting hard, or sitting back, accompanied by actions such as vertical ears, hunching back and trembling, it means that the sow has entered estrus, and this series of reactions is called standing still reaction. At this time, ordinary sows will allow people to touch their genitals and touch their genitals with their hands. Sows in estrus will show muscle tension and vulvar contraction. Touching the flank will make the sow nervous and tremble.
It should be reminded that the method of manual investigation often fails to find sows that have just entered estrus in time, because in the absence of the smell, sound and visual stimulation of boars, the time for static reflex of sows to appear is much later only through the back pressing test. If you check the situation once a day, you may have missed the best time for first mating or insemination when you find estrus sows. Therefore, when sows enter estrus, color markers should be applied in time for further observation and back pressure test. In the timing of mating, we should consider finding the lag of sow estrus.
External observation, back pressure test and stimulation of sensitive parts can confirm that sows really enter estrus.
1. Mucus can be drawn into filaments between index finger and thumb;
2. There is a static reaction when pressed back.
Second, try the wild boar to check the situation.
This is the most effective way to identify estrus, because estrus depends on whether sows accept the climbing of boars.
(1) Selection of experimental boars
Boars should meet the following conditions: it is best to be older, move steadily and have a strong sense of smell; Oral foam is rich, and it is good at attracting oestrus sows with sound, which is easy to cause olfactory reaction of oestrus sows; Gentle, patient, and will not attack the breeder under any circumstances; Obey the command, can cooperate with the breeder to check one by one in order, so that we can find the sows in estrus, but we don't want to leave the sows in estrus, so we can't continue the experiment.
(2) the method of checking the situation with boars.
1. If the experiment is conducted once a day, it should be arranged in the early morning, and the experiment in the early morning can find sows in estrus in time. If manpower permits, you can try twice in the morning and twice in the evening. Most pig farms in China are tested twice in the morning and evening.
2. When testing the situation, let the boar and the sow confront each other to test the situation, so that the sow can smell the boar and see the boar. Because the sow in estrus may also approach the boar, in the experiment, another inspector will conduct a back-pressing test on the sow who actively approaches the boar. If standing reflex appears when pressing the back, it is considered that the sow has entered estrus, so it should be registered at the beginning of estrus and marked. If the sow is unstable when pressing her back, it means that she is not in estrus or has passed estrus.
It is reasonable for some pig farms abroad to check estrus by riding back test before trying to love boars.
3. In order to effectively check the situation of the test boars, if possible, it is suggested to set up a door on both sides of these columns in the aisle every 8 ~ 10 (4 ~ 5 columns on each side), so that boars can be separated in these columns, or two people can separate the boars in this area with pig-driving boards, so that they can look for sows in estrus in this small area. Empty sows in groups can put boars between two fences on both sides of the aisle, and then try the other two fences after trying.
It is the best way to use boars to check the situation of pig farms. The characteristic performance of judging whether sows are in estrus is that sows have static reflex before trying to love boars. However, combined with the swelling and relaxation of sow vulva, the amount and viscosity of mucus and the congestion of vaginal mucosa, the judgment of sow estrus stage will be more accurate.
Third, the timing of reproduction.
If the mating time is controlled at 50% of estrus, the mating time of most multiparous sows is 16-32 hours after estrus begins. The picture below shows the estrus law and mating opportunity of sows.
The best mating time for returning sows and sows in estrus for more than 6 days after weaning should be 12- 18 hours after estrus begins. Sows should consider the appropriate breeding time in advance, but it is more important to determine it through other tests. Therefore, on the one hand, we can't accurately determine the duration of sow estrus. On the other hand, when the sow is found to be in estrus, it may have started several hours to more than ten hours ago. But we can have two or three inseminations or mating, so that the effective time of mating and fertilization includes the timing of mating, mainly the first insemination or mating. In this way, we can get the following findings: the relationship between estrus and the first and second mating opportunities is:
1. boars in estrus are checked twice a day (7-9 am and 16- 18 pm), and each sow is bred twice in estrus.
For returning sows and sows with an interval of more than 5 days from weaning to estrus, it was found that the first mating took place in the afternoon and the second mating took place the next morning. In the afternoon, it was found that the first mating was in the afternoon or evening, and the second mating was in the morning or noon the next day. Note that the interval between estrus and first mating is 3- 10 hour. The interval between the first mating and the second mating is 8- 16 hours.
For multiparous sows, if the interval between weaning and estrus is less than 5 days, the first mating is in the afternoon or the evening, and the second mating is in the morning. In the afternoon, it was found that the first mating was carried out the next morning, and the second mating was carried out the next afternoon or evening. Note that the interval between estrus and first mating should be 12-24 hours. The interval between the first mating and the second mating is 12- 18 hours.
For primiparous sows, we should not only check the starting time of estrus, but also pay attention to vulva and vaginal mucosa and mucus.
2. Observe and test the boar that is not in estrus twice every morning and evening (taking mating twice in estrus as an example).
For returning sows and sows whose interval from weaning to estrus is more than 5 days, it is found that the first mating is in the morning and the second mating is in the afternoon. In the afternoon, it was found that it propagated for the first time that afternoon and for the second time the next morning. The interval between the first insemination and the second insemination is 8- 16 hours.
For multiparous sows, if the interval between weaning and estrus is less than 5 days, the first mating is in the afternoon and the second mating is in the next morning. In the afternoon, it was found that the first mating was in the afternoon and the second mating was at noon or the next afternoon. The interval between discovery and mating is 3-8 hours, and the interval between two mating is the same as above.
For the first sow, it is also necessary to check the vulva and vagina mucosa and mucus.
3. reproductive tract and vulva examination factors mastered by reproductive opportunity. In addition to the above considerations, the interval between estrus and mating is judged according to the interval between initial mating and postpartum, weaning and estrus, and the vulva, vaginal mucosa and mucus are also examined and considered comprehensively.
Swelling of vulva: The vulva of sow begins to appear red and swollen during estrus, but at the beginning of estrus, the vulva of sow is highly red, swollen and moist. If the vulva swelling subsides slightly, it turns from bright red to slightly dark red, and the vulva is slack and drooping, except for the vulva fissure and its vicinity, most of the vulva is dry; The vulva of the first mating sow changes from high swelling and luster to wrinkles, and when the finger presses the vulva, the feel changes from hard to soft. At this time, sows are quiet, like to be close to people, have a strong desire to mate, and stand still when pressing their backs, which is the best time for breeding.
Mucus condition: The mucus secreted by sow in estrus is clear and thin, so it can't be drawn into silk between index finger and thumb. At the peak of estrus, the mucus becomes sticky and turbid, and can be drawn into 0.5 cm silk when it is slowly pulled between fingers, which is extremely smooth when it is rubbed between fingers. At this time, the mucus discharged from the vulva has dried and scabbed, and sometimes there are mats and other sundries, which is the best time for reproduction. Postpartum sows may not see mucus, and sometimes they can see a small amount of mucus from the vulva when pressing their backs. You should open the vulva and take a small amount of mucus for examination.
Vaginal mucosa: sows are allowed to touch genitals during estrus. At this time, you can open the vulva and check the vaginal mucosa of the sow. At the beginning of estrus, the vaginal mucosa of sows is flushed, and when estrus is full, the mucosa is swollen and shiny, and the mucosa is slightly dark red. This is the best time for breeding.
Fourth, breeding methods.
There are two ways to breed sows: natural breeding and artificial insemination.
(1) natural reproduction
Natural breeding, commonly known as "local crossing", drives the oestrus sows in the adaptive period to the breeding circle to enclose with the boars. If necessary, the reproductive technician assists the boar's penis to be inserted into the sow's vagina.
Clean the sow's vulva with dry tissue before breeding. When a large amount of urine accumulates in the foreskin cavity of some boars, the urine in the foreskin cavity should be squeezed out when the boars climb on the sows. Before the penis erection of boars, the foreskin of boars should be wiped clean with dry disinfectant paper towels.
The breeder should observe the whole breeding process and drive the sows back to the sow pen at the end of breeding.
Natural mating can be divided into single mating, repeated mating, double mating and multiple mating according to the interval and the number of boars used in one mating.
1. Single mating means that sows and boars mate once in one estrus. Its advantage is that the number of boars is small, but the conception rate and litter size are slightly lower than those of repeated mating, but if the breeder is very familiar with the estrus law of sows, the conception rate and litter size can be guaranteed. This feeding method is widely used by individual pig farmers.
2. Repeated mating refers to the second mating between sows and boars at intervals of 12 ~ 18 hours after the first estrus mating. This breeding method ensures that there are enough capacitated sperm in the fallopian tube during the best fertilization period of the egg, and its conception rate and litter size can be guaranteed, and it is easy to record the parent-child relationship of offspring.
3. Double mating means that one sow is mated with two boars every 15 ~ 20 minutes in a breeding cycle. The advantage of this breeding method is to increase the choice of eggs and the chances of fertilization with sperm from different genetic backgrounds. So it is helpful to improve the fertilization rate of sow eggs. The disadvantage is that the demand for boars is increasing. In addition, because the father of the piglets born by sows cannot be determined, it is impossible to register the pedigree, so it is not suitable for the production of breeding pigs and cannot be used for the identification of boars' offspring.
Commercial pig farms can carry out repeated breeding and double breeding on a sow at the same time, but this method will require more boars and the workload of breeding will double, so it is unacceptable in pig farms.
4. Reproduce sows many times. During the first estrus, after the first mating, the sow is mated every 12- 18 hours until the sow no longer has standing reflex in front of the boar. This breeding method has a large workload and a large demand for boars. This method is helpful to improve the conception rate of sows when they are immature in estrus.
(2) Artificial insemination
Artificial insemination of pigs is a reproductive technology that collects the semen of boars manually, examines and processes the semen, and then transports it to the reproductive tract of sows with instruments to fertilize them. The related detailed technology will be detailed in the third chapter.
(3) Reproduction times
Theoretically speaking, the conception rate of sows can be guaranteed as long as they mate normally once in estrus. However, in actual production, it is difficult to grasp the mating time, which can be solved by increasing the mating times, so that there are enough capacitated sperm in the fertilization site during ovulation. However, the more mating times, the higher the pregnancy rate. Generally speaking, if the breeder has some experience in estrus identification, the sow can achieve a satisfactory conception rate by mating twice (local hybridization or artificial insemination) at one estrus. Too many mating times, if the sow's estrus ends soon after the last mating, it is not only meaningless, but also increases the risk of metritis. It takes about 12 hours for sows to finish estrus after the last mating.
(4) Estrous mating registration and result analysis.
The oestrus registration of sows is helpful to discover the oestrus law of pigs and provide basis for grasping the breeding opportunity in the future. Breeding registration and result analysis are helpful to investigate the influence of the operation of breeding process on the conception rate and litter size of boars, as well as the level of conception rate and breeding opportunity, so as to identify boars more accurately and judge the overall breeding opportunity of pigs.