Determination of genetic and environmental factors affecting reproductive and productive characteristics of holstein bred in Kütahya conditions

The records of 740 Holstein cows were used to determine the fertility and milk production characteristics, the environmental factors affecting them, and the genetic parameters in Holsteins raised in a private enterprise in the province of Kütahya. Least squares analysis revealed that age at first calving (AFC), services per conception (SPC), service period (SP) and calving interval (CI) were significantly (P<0,05) affected by the breeding or calving year. In the study, least squares mean for AFC was 714.47 ± 3.001 d; for SPC was 1.91 ± 0.078; for SP was 111.40 ± 3.08 d and for CI was 401.06 ± 3.61 d. It was determined that the highest lactation milk yield (LMY) was reached in the third lactation, and this trait significantly (P<0.05) affected by the service period. Lactation length (LL) was only affected by calving year, whereas the effects of parity and SP were significant (P<0.05) on dry period (DP). The least squares means for LMY, LL and DP were 12119 ± 131 kg, 330.17 ± 3.27 ve 69.45 ± 1.94 d, respectively. The heritabilities of different traits, genetic and phenotypic correlations were examined, and it was found that the heritability of the calving interval (0.208 ± 0.103) was significant (P<0.05). In addition, it was concluded that genetic and phenotypic correlations between traits should be considered in selection programs.