Authors: OKAN ERTUĞRUL, MEHMET NURULLAH ORMAN, GÜVEN GÜNEREN
Abstract: This study was carried out to estimate the heritabilities and the genetic and phenotypic correlations between some milk production traits in Holstein cows in Ceylanpınar State Farm. A mixed-model equation was used in the study. The heritabilities and the genetic correlations were estimated by the Restricted Maximum Likelihood method (REML) for all the variables. Phenotypic correlations were estimated from measurements of the traits. Paternal half-sib correlations were used for the estimation of the heritability values. The heritabilities for the 2x305ME milk yield, the lactation length, the length of the dry period, and the calving interval were estimated to be 0.169±0.0287, 0.013±0.0205, 0.017±0.0270, 0.007±0.0240 and 0.138±0.0556, respectively. The phenotypic correlations between the lactation period and milk yield, the calving interval and the length of the dry period were 0.128, 0.006, and -0.005, respectively. The correlations between the milk yield and the calving interval and the length of the dry period were estimated to be 0.092 and 0.051, while the correlations between the length of the dry period and the calving interval was 0.621. The genetic correlations between the milk yield and the lactation length and the calving interval were 0.411 and 0.097, respectively. The genetic and phenotypic correlations for the milk yield and the age at first calving were 0.802 and 0.019, respectively. The correlations between the lactation length and the milk yield at first lactation and the age at first calving were 0.113 and -0.030, respectively. It was concluded that the use of selection methods would result in genetic improvements in the Holstein herd at Ceylanpınar State Farm.
Keywords: Cattle, Genetic correlation, Heritability, Holstein, Milk yield, Phenotypic correlation
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