Estimating of genetic parameters of milk production of Holstein Friesian breed in Burdur with different animals models

In this study, it was aimed to estimate the genetic parameters of milk yield of Holstein Friesian breed dairy cattle reared in Burdur province with different animal models. For this purpose, a total of 131 169 milk yield records in two separate data sets of Holstein Friesian breed dairy cattle between 2005-2010 and 2016-2023 were utilised. In the study, 305-day average milk yield of 6 189.6 kilgrams, the lactation period 266.2 days and dry-period 127.8 days were determined. The effects of calving season, calving year, farms and lactation order on milk yield characteristics were found to be significant. There was no difference between the lactation orders in terms of dry period. In the study, heritabilities of 305-day milk yield were estimated for each lactation order by using single trait model. Accordingly, estimates were obtained in the range of 0.16 - 0.28 in the first data set and in the range of 0.28 - 0.43 in the second data set. The heritability and repeatability of 305-day milk yields were estimated as 0.31 ± 0.04 and 0.34 ± 0.03 in the first data set, 0.30 ± 0.08 and 0.42 ± 0.07 in the second data set, respectively. In the repeated measurements model, heritability and repeatability of milk yield on the day of inspection were estimated as 0.23 and 0.28 in the first data set and 0.32 and 0.46 in the second data set, respectively. In the study, genetic parameters of milk yield on the test day were also estimated using a random regression model. The heritabilities estimated with this model are between 0.013 and 0.51 for the first data set and between 0.013 and 0.49 for the second data set.