First, the determination of insemination time cows estrus cycle is an average of 21 days, estrus duration is short, about 20 hours, ovulation generally occurs 10 to 16 hours after the end of estrus, so accurate estrus identification, timely insemination is Improve your fertility rate. The practice of insemination in dairy cows shows that the cows receive the climb (ie, the end of the estrus stage or the beginning of the late lye stage); the best fertility effect is obtained after the follicular development stage or the follicle maturity stage. The non-return rate of insemination from the time the cows accepted the start of the climb to the time of ovulation showed that the rate of conception was the highest when the cows received the inseminations from the eighth to the twenty-fourth hour. The inseminable person should master the following rules: the cow receives a climb in the morning and should lose sperm in the afternoon of the same day. If the climb is still accepted the next morning, the insemination should be performed again; if the cow receives a climb in the afternoon or the evening, it can be postponed until Insemination the next morning. If the inseminator is served by the field staff, a second insemination is generally performed 12 hours after the first insemination. If you are a small group of cows raised by individuals, the insemination time should be more flexible.
Second, insemination site and number of insemination
(1) A large number of insemination sites have demonstrated that there is no significant difference in the conception rate of insemination in the deep cervix, uterus, ovulation or ovulation uterine horn. Cervical deep (intracervical mouth) insemination is currently widely used.
(II) Frequency of insemination Frozen semen insemination, in addition to the reason of the cow itself, the cow's conception rate is mainly affected by the quality of the semen and the accuracy of the estrus identification. If the semen quality is good, the estrus identification is accurate, and a satisfactory fertility rate can be obtained with one insemination. Owing to the large individual differences in the time of ovulation, it is generally appropriate to hold one or two times. Blindly increasing the frequency of insemination not only fails to increase the rate of conception, but may also cause certain infections and uterine or reproductive tract diseases.
Third, the insemination method insemination method There are two kinds of opener insemination and rectal grasp insemination.
(1) Opener insemination method With the aid of an opening device, the cow's vagina is enlarged. With a certain light source (hand tube, frontoscope, headlight, etc.), the cervix is ​​found outside, and the vas deferens is inserted into the cervix at 1 to 2 cm. Inject semen, then remove the vas deferens and the opener. Although this method is simple and easy to grasp, the site of insemination is shallow, susceptible to infection, and the conception rate is low. Therefore, it is rarely used at present. (b) Rectal grasp Cervical insemination is similar to rectal examination. One hand wears thin-film gloves, extends into the rectum, pulls out excrement, looks for the cervix, and holds the outer end of the cervix to make it outside the cervix. The ring formed by the mouth and the little finger is flat (Figure 3 to 4). With the arm that extends into the rectum, open the vulva slit, and the other with the anaesthesia device inserted into the vulva (first obliquely when inserted and then level, do not insert the anaesthesia into the urethral opening). Using the hand on the outside of the cervix of the grip to cooperate with the hand holding the anaesthesia device, the anaesthesia device slowly moves beyond the folds on the inner side of the cervix (generally 42), and then the semen is injected. When grasping the cervix, the position is To be appropriate, it is beneficial to the cooperation of both hands, neither reliable nor too late, otherwise it is difficult to insert the insemination device into the deep cervix. The rectal grasp of the cervix method is widely used at home and abroad. It has the advantages of simple appliance, easy infection, deep insemination site and high conception rate. Its conception rate is 10% to 20% higher than that of the opener method, which greatly increases the reproductive rate and economic efficiency of dairy cows. At the same time, by touching the changes of the cow's uterus and ovaries with the rectum, the estrus or pregnancy can be further judged to prevent mis-allocation or miscarriage. Individual insemination technology has a great influence on conception rate, and experienced artificial insemination workers can obtain the best effect of conception. In hot climates, cows have short estrus time and insemination throughout the day is effective. Under this condition, the dairy breeder himself often obtains better results by performing artificial insemination operations, and receiving certain artificial insemination technical training is the guarantee for obtaining the best results. Frequent assessments of artificial insemination workers can help evaluate and improve their insemination quality and conception effects. In order to obtain a good fetal effect, semen should be stored in a container that can be checked regularly.
IV. Determination of the best interval between calving and the first insemination
Although the timing of early insemination after calving can advance the timing of cows' gestation, it is not wise to perform early mating after calving, because: 1 Postpartum lactation takes a while to recover in the early stages; 2 A young cow is born. Before the second pregnancies have not completed their own development; 3 early postpartum pregnancy rate is very low; 4 Practice shows that the cow's calving interval is less than 365 days is not beneficial; 5 more important reason is that the postpartum mating of their lactating period of less than 305 days. Therefore, many producers have controlled the post-harvest first mating time for 85 to 95 days after birth for some high-yielding cattle.
V. Recombination of cows
It is difficult for all inseminations to be successful in pregnancy, sometimes with multiple inseminations and still not gestation. Some, although able to gestationally normal, sometimes experience embryonic death and miscarriage after pregnancy. Normally, pregnancy in her pregnancy within the first days of her pregnancy is called failure of the embryo; her pregnancy is interrupted during the period of 43 to 151 days of pregnancy, and the death of the fetus is called an abortion. Embryo death may not have any obvious external symptoms. Therefore, it is very important for the cow to observe estrus after insemination. In particular, cows considered to be pregnant after 3 weeks of insemination without estrus should pay more attention. Cows who have been inseminated for 3 to 6 weeks should also continue to observe and find that they should return sperm in time to avoid time and economic waste. After the last insemination, if there is no estrus in 6-8 weeks, pregnancy diagnosis should be performed. If you are still not pregnant after multiple inseminations, you should eliminate them in time. If there are similar problems with the number of cows in the herd, they should be checked and dealt with promptly. Practice has proved that the above problems are often caused by poor management.
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