Studies On The Method Of Improving Liquid Storage Of Goat Semen And Elevating Fertilizing Ability Of Goat Spermatozoa

Artificial insemination(AI) is a key technology of accelerating excellent breeder reproduction and breeding by long or short storage semen. Long storage semen is freezing storage. The storage of semen, particularly in frozen state, causes ultrastructural, biochemical and functional damage to the spermatozoa resulting in a reduction of motility, viability, impaired transport and fertility. Pregnancy is low(about 50%) by AI with freezing storage goat semen, the result is a limit to the application of the technology of AI. So, we are investigating the liquid storage semen. The time that pregnancy rate got 80% was no more than 72 hours.In 2005,our laboratory developed a new diluent mZAP .we use this extender to store goat semen and find more than 30% of the spermatozoa having progressive motility after storage 9 days at 5℃.This makes a good base for the liquid storage of goat semen and let us imagine the probability of further extending the storage time.Therefore we studied on the base of this finding in order to further extend the storage time.We studied the effect of cooling velocity ,regular resuspending the stored semen,coating with diluents containing 20% egg yolk when collecting semen ,coating with extenders of pH 6.04 and pH 6.6 containing 20% egg yolk,different dilution rate after coating and centrifugation,treatment of diluents during the time of storage on the motility ,percentage of intact membrane and percentage of intact acrosome of goat spermatozoa.We find the cooling manner of 50ml water of 30℃make the motility of spermatazoa decline,the reason of this is because cooling velocity too quick from 30℃to 15℃.There is no effect of mixing on the storage of goat semen.In autumn ,the diluents of mZAP containing 2% egg yolk is best,while in spring we'd better not add egg yolk to mZAP extenders.Coating improve the effect of storage .The dilution rate of 1:20 is best of the three dilution rates. Treatment of diluents extend the storage time to 13 days.The results of IVF indicate that the 13 days spermatozoa have fertilizing ability,although their cleavage rate (56.5%)and morula/blastocyst rate(13.6%) are lower than that of fresh semen.