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Use of liquid nitrogen tank: preservation and use of frozen bovine semen

Time: 2020-09-15 10:10 Source: unknown Author: Bander liquid nitrogen tank Click: second
Cryopreservation of bovine semen is a special treatment of semen and preservation in ultra-low temperature to achieve the purpose of long-term preservation. It is usually stored in liquid nitrogen (- 196 ℃) and dry ice (- 79 ℃). Its advantages are that it can be preserved for a long time, and its use is not limited by time, region and the life span of male species. It can improve the utilization rate of bull. Now the preservation of frozen semen and how to thaw and insemination of cows are introduced as follows for reference. liquid nitrogen tank

Formula of diluent

12% sucrose solution 75 ml, glycerol 5 ml, yolk liquid 20 ml.

Dilution method

The qualified semen should be diluted by 1:2-5 times diluent. The principle of dilution should ensure that the number of sperm in each granule is not less than 30 million ~ 40 million, and the number of sperm running in a straight line after thawing is not less than 15 million.

freezing

Place a copper gauze net on the container containing liquid nitrogen, about 2 cm away from the liquid nitrogen surface. Use a dropper to drop the balanced semen into the copper gauze net according to a certain amount. Stop the last drop for 3-5 minutes. When the semen particles turn white, immerse them in liquid nitrogen immediately. Take all the semen particles out and collect them in the sperm storage bottle or gauze cloth bag, mark them, and then move them in immediately liquid nitrogen tank Storage in.

thaw

Put 1 ml of pre prepared 9% citric acid solution into a clean small test tube, and then put it into a warm water cup at about 40 ℃. Quickly take one granule of frozen semen and put it into the test tube. Gently shake to thaw, take out the test tube from the water cup, and then check the semen vitality, which is the qualified product.

Pay attention to sperm preservation, rapid thawing and microscopic examination

1. According to the performance requirements of liquid nitrogen tank, liquid nitrogen should be added regularly, and the lifting cylinder containing frozen semen in the tank should not be exposed outside the liquid nitrogen.

2. When taking the essence, use long tweezers as far as possible, and do not lift the lifting cylinder or gauze bag above the critical line (about 10cm on the top of the jar).

3. When taking out the frozen semen from the liquid nitrogen, gently swing it once or twice. Put the cotton stopper end of the plastic tube into the warm water of 35 ℃ ~ 40 ℃, and leave the sealing end 3 cm outside the water. When the semen in the tube is half melted, take it out immediately for standby.

4. After thawing, sperm motility should not be lower than the standard before it can be used for insemination to ensure normal fertilization. liquid nitrogen tank

5. The thawed semen should be transfused immediately, and should not be stored for too long. It should be thawed and inseminated now.

Timely insemination

The normal ovulation of cows is 6 hours to 12 hours after the end of oestrus. The survival time of sperm in the reproductive tract of cows is 12 hours to 20 hours, and it takes 4 hours to 6 hours for the process of capacitation to combine with the eggs. Sperm will arrive at the fertilized site of fallopian tube in 15 minutes. Therefore, it is a prerequisite to increase the conception rate that sperm arrive at the fertilized site of fallopian tube earlier than the egg.

1. Suitable insemination time: in the late estrus of cows. At this time, the cow's spirit is stable, the vulva swelling disappears, and the vagina no longer flows transparent liquid. Rectal examination of follicular swelling, surface tension, there is a touch is broken feeling, at this time insemination time.

2. Suitable site of insemination: 1 cm of the internal orifice of the cervix, that is, the base of the uterine body. If it is too shallow, it is easy to cause semen outflow; if it is too deep, it is easy to damage the uterine mucosa.

3. Suitable method of insemination: the method of insemination by rectum and cervix. The left hand is inserted into the cow's rectum to gently hold the back of the cervix. With the right hand, the insemination device is slowly inserted into the cervix from 5 cm to 10 cm above the vulva syncline (to avoid the urethral orifice), and then horizontally inserted into the cervical orifice. Slowly cross the wrinkled wall of the cervical tube and reach the base of the cervix. After slowly injecting semen, the inseminator is slowly pulled out.

4. Suitable insemination times: 1 ~ 2 times is suitable. The first insemination can be carried out at 6-12 hours after oestrus climax in cows, 18-20 hours in buffaloes, and the second insemination in 8-12 hours interval. liquid nitrogen tank

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