Effect of long term storage in LN2 on bacterial load and preservability of semen in Murrah bulls

Abstract

Successful preservation of semen for longer period can be achieved by maintaining the viability of spermatozoa from its collection till its use for insemination. Therefore, we perceived the idea to determine the effect of long term storage of cryopreserved buffalo semen on sperm quality, bacterial load and fertility. Twenty years semen samples (1981-2000) from twenty bulls and the data on conception rates of these bulls were collected from record room at ABRC, ICAR- NDRI, Karnal. The data was analyzed using least square analysis. The differences in individual motility percent in the semen between estimated initially at the time of freezing and estimates after storage (at the time of evaluation) were 6.49, 14.09, 13.13 and 6.02 percent, respectively. Even after long term storage (up to 20 years) there were little changes in the sperm motility percent. Changes in non-eosinophilic sperm count, sperm abnormalities, HOST and acrosome status, were less up to 20 years storage of semen in liquid nitrogen and the differences were non-significant between different years of storage semen in liquid nitrogen. In similar fashion the microbial load in semen was decreased with the increased storage period of semen in liquid nitrogen, but the differences were non significant. The differences in sperm motility percent between 370C and room temperature were not significant, but the temperature and incubation period significantly (P<0.01) influenced motility percent estimates. Whereas, temperature-incubation period interaction was not found to be significant. The conception rate and sperm motility was highly and positively correlated (r=0.67 and 0.55) with sperm oocyte attachment. It can be concluded that there was little change occurred in semen quality even after twenty years of storage in liquid nitrogen without affecting fertility of semen.