a Genetic and Phenotypic Relationship of Age at First Calving and Early Growth Traits of Holstein Friesian×Boran Crossbred Dairy Cattle

The objective of this study was to estimate the genetic and phenotypic correlation between age at first calving and early growth traits for Holstein Frisian x Ethiopian Boran crossbred cattle in the central highland of Ethiopia. The data used for this study was sourced from records of Holetta Agricultural Research Center dairy cattle herds’ farm collected from ۲۰۰۰ to ۲۰۱۹. The genetic and phenotypic correlation values for age at first calving (AFC) and early growth traits were estimated using WOMBAT software through multivariate analysis of the animal model. The estimated direct genetic correlation between age at first calving and early growth traits ranged from a weak positive (۰.۱۱±۰.۳۳) for yearling weight (YW) to a strong positive of ۰.۷۷±۰.۳۶ for weaning weight (WW). The phenotypic correlation ranged from a moderate negative of -۰.۴۴±۰.۰۳ for AFC and YW to a weak positive correlation of ۰.۱۲±۰.۰۴ for AFC and YW. Both environmental and genetic effects could influence phenotypic correlations of the age at first calving and early growth traits. The results of the genetic correlation between early growth traits and AFC indicate that early growth traits should be given some consideration in the selection criteria of heifers. A cow with high growth performance has poor reproductive performance due to genetic antagonism between those traits. Selection could be done with caution.The objective of this study was to estimate the genetic and phenotypic correlation between age at first calving and early growth traits for Holstein Frisian x Ethiopian Boran crossbred cattle in the central highland of Ethiopia. The data used for this study was sourced from records of Holetta Agricultural Research Center dairy cattle herds’ farm collected from ۲۰۰۰ to ۲۰۱۹. The genetic and phenotypic correlation values for age at first calving (AFC) and early growth traits were estimated using WOMBAT software through multivariate analysis of the animal model. The estimated direct genetic correlation between age at first calving and early growth traits ranged from a weak positive (۰.۱۱±۰.۳۳) for yearling weight (YW) to a strong positive of ۰.۷۷±۰.۳۶ for weaning weight (WW). The phenotypic correlation ranged from a moderate negative of -۰.۴۴±۰.۰۳ for AFC and YW to a weak positive correlation of ۰.۱۲±۰.۰۴ for AFC and YW. Both environmental and genetic effects could influence phenotypic correlations of the age at first calving and early growth traits. The results of the genetic correlation between early growth traits and AFC indicate that early growth traits should be given some consideration in the selection criteria of heifers. A cow with high growth performance has poor reproductive performance due to genetic antagonism between those traits. Selection could be done with caution.

Keywords:

Crossbred , Growth trait , Crossbred Dairy Cattle , Age at first calving