Meta-analysis of seminal traits affecting bull fertility.

Abstract

The pedigree information on bulls was collected from Frozen Semen Bank (FSB). Male reproductive data on seminal characters (semen volume (SV), sperm concentration (SC), initial progressive motility (IPM), post-thaw motility (PTM), and total spermatozoa (TS)) were analyzed to calculate their repeatability, heritability, genetic correlation, phenotypic correlation, and environmental correlation values. The principal component analysis revealed SV and SC were the two most important characters among the five seminal characters that can be further used. The repeatability value for seminal characters was very low (0.02-0.2). The sire component of heritability value varied from very low to low (0.0001 to - 0.24). The dam component of heritability value varied from very low to high (0.01 to 0.64). The genetic correlation value calculated from the sire component indicated a slightly antagonistic relationship between SV and SC (- 0.007) and SV and PTM (- 0.049). The environmental correlation value was found to be negative for all the traits except the value calculated from the dam component between SC and IPM (0.027). The phenotypic correlation values between the seminal traits were low and mostly negative except between SC and IPM (0.107) and PTM and TS (0.109). Statistically significant correlation was observed between PTM and SV (- 0.157), PTM and IPM (- 0.145), PTM and TS (0.109), and SC and IPM (0.107). Since the estimated heritability, repeatability, and the correlation values were found low, individual selection method cannot be applied on these bulls.