Estimation of variance components and genetic parameters for milking, udder and milk yield traits in holstein cattle

The aim of this study is to estimate variance components and genetic parameters for milking, udder and milk yield traits in Holstein cattle. The material of the study consisted of 1001 cows of Holstein cattle in a private farm in Bursa. The study was conducted between December 2017 and March 2018. Some udder characteristics were measured before milking in 4 different periods and morning milking and milking characteristics were determined. ANOVA was used to determine the factors affecting these properties, REML was used for estimation of variance components. Two models were used for variance components. In the first model, besides the fixed factors, only animals were included as a random factor, while in the second model, the permanent environmental impacts from animals and coincidental factors were added to them. Minitab for ANOVA, and MTDFREML for REML were used. The mean for the rear teat length (RTL), rear teat thichness (RTT), rear teat distance (RTD) and the udder height (UH), respectively; 4,78, 2,84, 4,36 and 56,71 cm. The mean values for milking time (MT) and milking speed (MS) were found to be 5.10 min and 2.75 kg/min. Milk yield in the last milking, average daily milk yield in the last two days (Avr24-48), milk yields from morning, evening and night milk respectively; 13,9, 40,6, 14,3, 12,4 and 13,8 kg. Heritabilities for model 1 and model 2 for RTL 0.21, 0.02, RTT for 0.15, 0.04, for RTD 0.78, 0.14, for UH 0.73, 0.46 estimate it were. The repeatabilities were 0.18, 0.10, 0.59 and 0.24, respectively. Heritabilities were estimated as 0.92, 0.38 for MT, 0.79 and 0.24 for MS for two models. The repeatabilities were estimated between 0.00 and 0.54. The heritabilities for Avr 24-48 were estimated to be 0.72 and 0.12, and the repeatability was 0.53. Genetic correlations were 0.34 for MS-Avr24-48, -0.86 for MT-MS, 0.36 for RTL-MT, -0.29 for RTL-MS, and 0.26 for RTT-MT, for RTT-MS -0.18, found. According to the results of this study, it can be said that there is sufficient genetic variation in udder, milking and milk yield characteristics. Sufficient genetic progress can be achieved by selection.