The frozen semen breeding has the advantages of efficient use of excellent breeds of male animals, no time and geographical restrictions, and no restrictions on the life of the males. The frozen semen of cattle is the earliest and most successful research, and the frozen semen of cockroach is still in the experimental research stage, and what are the factors affecting its conception rate?
1. Cryogenic protectant - egg yolk (cholesterol)
Compared to the conception rate of bovine frozen semen, sputum frozen semen is relatively low. It is well known that cholesterol affects the fertility of horses and sputum semen after resuscitation. Therefore, lowering the proportion of cholesterol in the diluent may increase its conception rate. JJRebecca and other studies found that 20% egg yolk, 5% egg yolk, 20% egg yolk + 60mmol / L hydroxypropyl-β-cyclodextrin were added to the frozen dilution containing 2% ethylene glycol, respectively. It is 6.25%, 46.5%, 58.5%. I.F. Canisso and other studies found that the average conception rate of lactose-EDTA and lactose-yolk two frozen dilutions was 48.33%, the difference was not significant, but in daily use, the simple and convenient lactose-yolk dilution was recommended. RROliVerira and other studies found that fresh refined S-MEDIUM was diluted to 1.2 × 108 / mL, and then added 0,1,2,3mg / mL cyclodextrin cholesterol clathrate (CLC) in lactose-EDTA diluted semen. The semen was treated at room temperature for 15 min, centrifuged, twice diluted and frozen. Although the addition of CLC improved sperm viability (vigor, plasma membrane integrity, acrosome integrity), it reduced the fertility rate of the mare. It can be seen that the high yolk or cholesterol content in the frozen diluent does reduce the conception rate of the mare.
2. Cryoprotectant - glycerin
Studies have found that glycerol has some toxicity to sperm, and the high content is not conducive to the low temperature freezing of sperm, and even affects the conception rate. M.Vida-ment and other studies have shown that glycerol is toxic to horses and cockroaches, and the toxic dose of scorpion sperm should be half of that of horse sperm.
Therefore, as a cryoprotectant for sputum semen, glycerin or its substitute dimethylformamide, ethylene glycol, etc. should not be added in an amount of more than 5%, preferably about 2.2%, to ensure high vitality and conception rate. .
3. Artificial insemination technology
At present, research on using artificial insemination technology to improve the conception rate of female parent is still under investigation. JVOliVerira and other studies have shown that when the input fresh concentration is 5×10 8 /mL, the conception rate of the female pupa is 40% (6/15); and when the input fresh concentration is 10×108/mL, 驴The conception rate was 73% (11/15); in the 24 hours after ovulation, the insemination was performed once every 8 hours, and the insemination site was in the cervix (shallow insemination) and the uterine horn (deep infusion). Fine), the results of the conception rate were 0 (0/12), 28.3% (13/46). It shows that measures such as deep insemination, increase in insemination frequency and insemination concentration can greatly improve the conception rate of females.
The cryopreservation study of sputum semen at home and abroad is slower than other livestock. In recent years, due to the need to produce oyster meat and donkey-hide gelatin, the oyster industry has emerged. At the same time, sputum semen cryopreservation and artificial insemination technology have also become research hotspots. Although some progress has been made in the research of these technologies, the fertility and mortality rate of sputum frozen semen needs to be improved.