Semen from six adult male Black Bengal goats (Capra hircus) 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. تفاصيل المقالة

Black Bengal goat is the heritage and one of the potential genetic resources of Bangladesh. Genetic and phenotypic parameters for semen characteristics and their relationships with scrotal circumference in Black Bengal bucks were estimated in this experiment. Genetic parameters were estimated by residual maximum likelihood procedure, fitting an animal model ignoring maternal genetic or permanent environmental effects. The least-squares means of semen volume (mL/ejaculate), sperm concentration (109cells/mL), mass motility (%), sperm livability (%) and normal spermatozoa (%) were 0.56, 2.55, 79.7, 86.8 and 90.5, respectively. Season of collection and scrotal circumference significantly affected all semen characteristics studied. Age of bucks affected all the semen characteristics, except mass motility. Body weight had a significant effect on semen volume and mass motility. Heritability estimates were moderate for sperm concentration (0.38) and low for semen volume, mass motility, sperm livability and normal spermatozoa (0.05 to 0.18). Phenotypic correlations ranged from slightly negative (-0.001) to moderately positive (0.42) and the genetic correlations ranged from moderately negative (-0.37) to strongly positive (0.99). Sperm concentration was the only semen trait of Black Bengal goat where reasonable genetic progress may be possible through selection. Selection for increased scrotal circumference should have favorable correlated response in semen characteristics. تفاصيل المقالة