Artificial insemination technique of small tail Han Sheep

? 1. Ewe estrus identification is the key.

The estrus performance of small-tailed Han sheep is different from that of goats, and it is not obvious. Only a few sheep can be identified by this method. The main methods are estrus test and vaginal examination.

⒈ test method

The method of testing the estrus is to find the ewe correctly by using the ram to find the ewe. However, when using this method in the vast rural areas, it is necessary to separate the ram from the ewe to ensure the sexual desire of the ram to find the ewe. When the ram is put into the ewe herd, when the ram sniffs the ewe with its nose or teases the ewe with its hoof, the ewe stands still, or the ewe takes the initiative to approach the ram, it is the ewe, and then it is judged by vaginal examination.

⒉ vaginal examination

The vaginal mucosa of the ewe is congested red, the surface is smooth and moist, there is transparent mucus exudation, the cervix is congested, relaxed, open, and when there is mucus outflow, it can be defined as estrus.

? 2. Semen collection and semen treatment techniques of sheep

Sheep artificial insemination technology can be divided into fresh semen artificial insemination and frozen semen artificial insemination.

⒈ semen collection

Install and disinfect sheep false vagina before semen collection, apply a little sterilized Vaseline in front of the inner tube 1-2-3 to achieve the purpose of lubrication. The warm water of 40-42 ℃ (150-180ml) was slowly injected from the irrigation hole between the false vaginal shell and the inner tube, so that the water temperature between the shell and the inner tube reached 38-40 ℃. The water temperature varied with the season, and the water temperature in winter was slightly higher than that in summer. Blow an appropriate amount of gas into the false vagina to adjust the pressure of the false vagina, and it is appropriate to make the entrance of the false vagina "Y" or "X". Then use ewes as Taiyang sheep, preferably ewes in estrus, small-tailed Han sheep taller than Dupo sheep, when it is not easy for Dupo sheep to climb hiking ewes, the ewes should be placed in a slightly lower place. When the ram climbs the back of the ewe, quickly introduce the ram penis into the false vagina, wait for the ram to ejaculate, erect the false vagina, let the collecting cup face down, and remove the collecting cup for semen examination. If the ram climbs the hip several times without ejaculation, the ram should be pushed down several times before semen collection, or the ram's movement is not enough, the ram's movement should be strengthened.

The normal ejaculation volume of Dupo sheep is 1-1.5ml, which is milky white and cloudy. The density and deformity rate are observed under the microscope. When the sperm motility is more than 0.6, the semen density is above "medium". That is, 20-4 billion sperm per milliliter of semen can be used for production, and the sperm deformity rate must be ≤ 15%.

Semen that is qualified after examination can be used for insemination directly, but it is best to dilute it according to the dilution multiple requirement. If the semen is not preserved at that time, it can be diluted with VB12 or milk (boiled and filtered with 8 layers of gauze).

? III. Insemination technique

⒈ insemination

Timely and accurately transfusion of a certain amount of high-quality semen into the cervix of ewes is the key to ensure ewes to conceive. In the operation of insemination, the vulva of the ewe to be inseminated should be scrubbed and disinfected with bromogeramine, then scrubbed with water or normal saline cotton ball, the rear rib of the ewe should be placed on the crossbar with a height of about 70-80cm above the ground, or two people lift the hind legs of the sheep, and the insemination personnel should insert the opener or endoscope into the vagina of the ewe, find the cervix by adjusting the depth and angle, and slowly insert the insemination into the cervix. Slowly inject the required amount of semen (original semen .05-0.1ml), and then massage the inseminal apparatus back and forth for about 1 minute. After pulling out the opener or endoscope from the vagina, pat the ewe's thigh to make its cervix contract and help the semen not to flow out.

Time and frequency of ⒉ insemination

When the ewe begins to show estrus, the first insemination is controlled after 8-12 hours (frozen semen is appropriately delayed for several hours). The characteristics of cervical mucus can also be used as a sign of timely insemination, which marks that the transparent mucus becomes turbid and finally becomes cheese-shaped, the effect of insemination is the best at this time. Generally take one trial, two insemination, that is, the first insemination in the afternoon after the trial in the morning, and another insemination in the next morning; in the afternoon, one insemination in the morning and one in the afternoon.

The accurate judgement of ewe estrus by ① is the key to ensure the conception rate. It is suggested that the estrus test method should be used to identify estrus.

② deep insemination 1.5-2.5cm can effectively increase the conception rate, and as deep as possible, so that the conception rate may be high.

③ in winter when the temperature is low, the seminal apparatus should be heated to body temperature and then put into semen to prevent sperm from freezing shock.

④ insemination device should be rinsed with water immediately after use, and washed with distilled water for 1-2 times, each sheep was disinfected with alcohol cotton ball, and then rinsed with normal saline twice before use.

⑤ avoids all equipment that comes into contact with sperm with water, which can lead to sperm death, so you can rinse it with saline more than twice before use.

Ewes after ⑥ insemination should stay in the original Baoding position for a while and then release their activities to prevent semen reflux.

⑦ for virgin sheep insemination, because of its vaginal stricture, insemination can not reach the cervical mouth, can only do vaginal bottom insemination, so insemination, the amount should at least double.