Essentials for the technology of frozen sperm breeding in Liaoning Cashmere Goats

With the further development of the Liaoning cashmere goat breeding industry, the use of excellent male rams to freeze the breeding of species, improved areas of low-yield groups and farmers gradually increased. However, judging from the effect of the application in recent years, the fertility rate of freeze-thawed mating in each region varies by a large margin, generally ranging from 25.6% to 86.8%. According to some experiences of freeze-thawing production, thawing and freezing, the author made a summary of the technical points of Liaoning Rongrong goats when they were frozen and matched, so that they can be used for reference by the farmers.

1, according to the age of the ewes to choose the appropriate method of insemination

When spermatozoa were mated, the fertility rate of the ewe ewes was higher than that of the young ewes. The effect of intracervical insemination was better than vaginal insemination. In estrus, the ewe's ewes have good opening of the cervix, and the cervix insemination can achieve a satisfactory fetal effect. The general insemination depth is 0.5 cm to 1.0 cm in the cervix; the young ewes are in the estrus state. The cervix is ​​in a semi-closed or slightly open state and cannot be inseminated in the cervix. The vaginal insemination can be performed at the bottom of the vagina. That is, when the ewes are in the inverted state, the semen is fed into the gap between the cervix and flows into the gap between the cervix. In the mouth of the cervix, the insemination is completed, and the hen's hindquarters are suddenly beaten by hand to promote the contraction of the ewes' abdominal muscles, so as to facilitate the operation of the sperms.

2, grasp the estrus heat, timely breeding

Artificial insemination and breeding, especially the use of frozen sperm to control the oestrus oestrus, is crucial to improve the fertility rate of the ewe. Esh heat can be inferred from sexual behavior, physiological changes in the reproductive tract, and estrus time. The proper estrus symptoms for ewe are: frequent swinging tails, active approach to rams and rams, constant buzzing, crawling across other ewes or crawling by other ewes, loss of appetite, and increased fighting. Observing the vagina with an opener and a flashlight: Visible mucus is slightly viscous, cervix opening is good, vaginal mucous membrane is pink, whitish mucous membrane and old red mucous membrane respectively indicate that the estrus does not reach the heat or is over-fired. The estrus duration of ewe differs depending on the ewe's age and sensation. The age of sheep is generally 24h ~ 36h, young sheep are generally 5h ~ 12h, and very irregular, aged sheep is generally 12h ~ 24h. The most appropriate breeding time in the middle and late estrus. Therefore, ewe ewes should be bred 12h after estrus, young sheep can not rely on estrus, should be estrus, and elder ewes should be estrus 8h ~ 10h after mating.

3, Baoding breeding ewes

In the artificial insemination operation, Baoding of the ewes should facilitate the flow of semen to insemination sites. There are two general postures. If you use a breeding stand to protect the estrus ewes, they should show a low angle of 35 degrees before and after, which is conducive to semen operation. If you do not use Baoding frame, you can pour two ewe's hind legs by one person and move your abdomen forward. The legs of the sheep are clamped by the legs, which is also conducive to the operation of the sperm to the site of fertilization. In the Baoding process, care should be taken to avoid brutality and try to keep the ewes in a state of comfort in order to avoid the ewes struggling, causing the inseminated personnel to be injured or inseminating the guns to injure the ewes vagina to cause bleeding and infertility.

4. Thawing of frozen semen

There are many thawing methods for frozen semen, and scientific thawing methods can maintain thawing semen with the best thawing activity and acrosome integrity, and relatively long survival time. High temperature rapid thawing effect is good, but not easy to grasp. Regardless of the method used, care must be taken that the temperature of the semen does not exceed room temperature after thawing.

4.1 Fine tube frozen essence

The tube of frozen sperm (volume 0.25ml) was placed in warm water at 40°C and shaken constantly, and the see-through semen in the slim tube became transparent and immediately taken out (about 8s). Wipe off moisture with dry sterilization gauze.

4.2 Granular frozen essence

4.2.1 Wet Thawing

Take 3-4 granules of lyophilized powder, place it in a clean 40°C water bath tube containing 0.5 ml of 2.9% sodium citrate thawing solution, and remove it when it is melted to 2/3, and use hand temperature to completely dissolve. The method is suitable for use when there are few estrus ewes.

4.2.2 Dry thawing

Sterilize the sterilized aluminum lunch box (medium size) in a 40°C water bath, then take a tablespoon of frozen essence and spread it to the bottom of the box to make it as evenly distributed as possible. Then shake the lunch box till it is completely dissolved and tilt the lunch box. Semen is inhaled into the insemination gun or other storage container for use. Note that the container should be warmed to 25 °C ~ 37 °C. The law applies to the use of large numbers of ewes.

5, the normalization of insemination

After the genital area of ​​the ewes was disinfected and cleaned, the inseminators took openers in one hand and the handles were parallel to the ground. Tilt into the ewe's vagina and when it reaches the bottom of the vagina, rotate 90 again. Open an opener and use a flashlight to perform vaginal or cervical insemination. When the insemination gun is withdrawn, the opener should be slowly rotated and the inseminat should be withdrawn slowly to prevent the negative pressure from causing the return of the semen; the tips of the opener must not be closed to prevent the semen from being carried out by the injection of mucus. At the same time, we must pay attention to the insertion of the cervix when it is close to the body temperature of the ewes, and avoid the chilling of the ewes causing the ewes to blame or burn the ewes vagina.

6, pay attention to the aseptic operation

The opener, insemination gun, and tweezers are sterilized with high-temperature steam and rinsed with normal saline before use. After cleaning the genital area of ​​the ewes, they can be cleaned with 0.1% KMnO4 and then wiped with a clean towel and water. The breeding room should be smoke-free and dust-free and regularly sterilized with ultraviolet radiation. For utensils that cannot be boiled with high temperature, use a 75% alcohol scrub to dry and rinse with sterile saline or 2.9% sodium citrate solution before use.

7, the quality of semen must meet the insemination requirements

After thawing microscopic examination at 37 °C, the vitality is greater than 0.3 can be used for insemination, the effective number of sperm per sheep per insemination should not be less than 5107. Frozen sperm should be used immediately after thawing, otherwise it will reduce the rate of conception.

8, preservation of frozen sperm

The stored frozen essence must always be immersed in liquid nitrogen. When the liquid nitrogen in the liquid nitrogen tank is reduced to one third, it must be promptly replenished. When thawed, the amount of unthawed semen exposed to air must not exceed 5 s. To extract and remove frozen essence, use a bucket containing liquid nitrogen to reduce the exposure time of the frozen essence to the air.

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