Environmental factors affecting milk yield and fertility traits of simmental cows raised at the Kazova state farm and phenotypic correlations between these traits

Abstract

The aim of this study was to investigate environmental factors affecting milk yield and fertility traits of Simmental cows raised at the Kazova state farm and the phenotypic correlation between these traits from 1473 records between 1992 and 2001. The least square means of 305-days milk yield, lactation duration, dry period, service period, calving interval, gestation length and number of inseminations per conception (NIPC) were 4700 kg, 300 days, 81 days, 94 days, 379 days, 283.6 days and 1.76, respectively. The effect of calving year on milk yield and fertility traits was statistically significant (P < 0.001). The effect of calving age on gestation length and milk yield was also statistically significant (P < 0.001-P < 0.05). The effect of calving season on gestation length, 305-days milk yield and NIPC was also statistically significant (P < 0.001-P < 0.05). Birth type did not significantly affect any traits, except for gestation length. The phenotypic correlations between 305-days milk yield and lactation duration (0.39), between NIPC and service period (0.81), between NIPC and calving interval (0.77), between calving interval and service period (0.96) and between calving interval and gestation length (0.12) were statistically significant (P < 0.001). Correlations between milk yield and fertility traits (0.09-0.77) were statistically significant (P < 0.001-P < 0.05), except for gestation length. These results are acceptable and it can be concluded that Simmental cattle are raised successfully on this farm and under Turkish conditions.