Effects Of LDL And PCS On Cryopreservation And Contents Of Lipids In Sheep Spermatozoa

For the lower pregnant rate of AI with sheep frozen semen than that of natural mating, the sheep frozen semen was still not used commercially. One of the reasons of lower pregnant rate might be the depletion of cholesterol from sheep spermatozoa during freezing, leading to premature capacitation. Therefore, the paper studied on the changes of cholesterol and phospholipids of sheep spermatozoa during freezing which was protected with egg yolk (EY). Then low density lipoprotein (LDL) was used to instead of egg yolk in diluents to study on the protection of spermatozoa from cholesterol depletion. Additional, Potassium cholesterol sulfate (PCS) was supplemented to LDL diluent and EY diluent to study on the ability of LDL+PCS and EY+PCS to maintain the cholesterol and phospholipids contents, motility, membrane and acrosome of spermatozoa.1. The cholesterol contents and cholesterol and phospholipids ratio of sheep sperm were decreased from 234.54 to 163.76nmol/10~9sperm and from 0.54 to 0.36 freezing, when the egg yolk was added to the semen diluent.2. When EY was insteaded with LDL in sheep semen frozen diluent, LDL could maintain the cholesterol content and the ratio of cholesterol and phospholipids. LDL could also increase the motility of frozen sheep sperm. Therefore, LDL could be used to replace the EY in diluent, and the suitable dosage was 9g LDL in 100 ml diluent.3. In LDL diluent, PCS could increase the ratio of cholesterol and phospholipids, but did not influence the membrane and acrosom of frozen sheep spermatozoa. PCS was harmful to sheep sperm in LDL diluent during freening.4. In EY diluent, PCS could maintain the cholesterol content and the retio of cholesterol and phospholipids of frozen sheep semen and increase the motility, the rate of no-effected membrane and acrosome. EY diluent supplemented with PCS might have batter protection to sheep sperm than that of EY only in diluent during freening.