Genetic Parameters Estimation for Reproductive Traits of Pure Jersey Breed at Adea-Berga Dairy Research Farm

The data collected from 1986 to 2019 at Adea-Berga Jersey herd improvement farm was used to estimate genetic parameters for reproductive traits (age at first service (AFS), age at first calving (AFC), calving interval (CI), days open (DO) and the number of services per conception (NSPC)). The traits were estimated by using WOMBAT software. Univariate analysis was undertaken for each trait for the estimation of parameters (heritability, repeatability, and breeding values) and genetic and phenotypic correlations were estimated with bivariate analysis. The direct heritability estimates for AFS, AFC, CI, DO and NSPC were 0.05±0.08, 0.05±0.05, 0.03±0.02, 0.04±0.02 and 0.001±0.02, respectively. Low direct heritability estimates for the reproductive trait in this study indicate that improvements of the traits are possible through management rather than through genetic selection. The repeatability of CI, DO and NSPC were 0.09±0.02, 0.08±0.02, and 0.05±0.02, respectively. The genetic correlations between reproductive traits varied from -0.10±00 to 1.00±0.11 while the values of phenotypic correlation were found ranging from 0.03±0.04 to 0.98±0.00. The positive direct genetic correlations among traits in the present study indicated that the selection of one trait might improve the other trait. The average breeding values for AFS, AFC, CI, DO and NSPC were -0.00948 months, 0.02269 months, -1.13339 days, -3.00389 days, and -0.00021, respectively. The negative breeding values for reproductive traits tend to be associated with below-average performance. In conclusion, improvement of management (feeding, disease climate control, etc.) should be implemented to improve the reproductive traits of the pure Jersey cattle population. Selection and breeding using worldwide sire semen in the farm also creates genetic variability within the herd and improves heritability, genetic correlations among reproductive traits, and breeding values.