A Comparative Study of Fresh and Frozen-Thawed Semen Quality in Relation to Fertility of Black Bengal Goats

Abstract

Semen from six adult male Black Bengal goats (<em>Capra hircus</em>) was collected to compare the fresh and frozen-thawed semen quality and investigate its relationship with the fertility. Each collected samples was divided into two parts: One part of semen was used as fresh and another part was filled into 0.50 ml straws, sealed, cooled (5 ˚C) and equilibrated for freezing.In both cases, semen was diluted with commercial Triladyl diluent (a Tris based diluter). The motility and morphology of fresh and frozen-thawed semen was subjectively evaluated by one operator. It was revealed that motility and sperm abnormality of the frozen semen differed significantly (P<0.05), but differed insignificantly in fresh semen between males. Besides these, fresh and frozen-thawed sperm motilities also differed significantly (P<0.01) between males which varied from 70.83±1.54 to 74.23±1.59% and 44.17±2.39 to 52.31±1.08%, respectively. A significantly (P<0.01) higher sperm abnormalities was observed in frozen-thawed semen (11.18±0.42 to 16.55±0.09%) than that of fresh semen (8.82±0.24 to 9.71±0.52%). Cervical inseminations were performed with fresh and frozen-thawed semen in 997 and 1004 female goats, respectively, both at Nucleus Breeding Flock (NBF) and four project areas. Fresh semen showed significantly (P<0.01) higher kidding rates (59.8%) than that with frozen-thawed semen (43.9%). The motilities of fresh and frozen-thawed semen were positively correlated (0.526 and 0.987; P<0.01), whereas the proportion of morphologically abnormal spermatozoa was negatively correlated (-0.530 and -0.776) with fertility of Black Bengal goats. Males with a higher motility and lower proportion of abnormal spermatozoa provided better fertility.