Genetic Trend and Heritability Estimates for Milk Production Traits of Jersey Breed in Ethiopian Highland Environment (Published)
The purpose of this study was to assess the genetic merit of Jersey breed under Ethiopian highland environment for further improvement. The long-term performance data (from 1986 to 2016) of Jersey cattle imported from Denmark and maintained at Adea Berga, central highland of Ethiopia was evaluated. Variance components, heritability, repeatability, genetic and phenotypic correlations and estimated breeding values for three milk production traits of Jersey cows were estimated by WOMBAT software while genetic and phenotypic trends were estimated by SAS 2004 software using regression analysis. Heritability estimates for LMY (lactation milk yield), DMY (daily milk yield) and LL (lactation length) were 0.128, 0.113 and 0.037 respectively, while the corresponding repeatability estimates for these traits were 0.33, 0.37 and 0.1 respectively. The magnitude of correlations were ranged from low with negative value -0.04 (DMY-LL) for phenotypic correlations to highly positive value with 0.97 (LMY-LL) for genetic correlations. The estimated annual genetic progress for LMY, DMY and LL were 2.46 kg, 0.0043 kg and 0.175 days indicating annual increase in breeding values over the study period. On the other hand the annual phenotypic trends for LMY and DMY were negative (-8.1 kg and -0.44 kg respectively) which mean directed into unfavorable direction but for LL it was small and positive (1.02 days).