Authors : Suleyman cilek and Ali Kaygisiz
Abstract: In this study, it was aimed to calculate genetic parameters of 305 day milk yield and breeding value estimation of Brown Swiss Cattle reared on Ula State Farm. Later, analysis results were compared. In this study, 830 first lactation records of daughter sired by 58 bulls that had at least 5 daughters were used. Additive genetic variance, error variance, permanent variance, environment variance, heritability, repeatability and breeding value were estimated using REML animal model. Heritability of test day milk yields (0, 10) was higher than the heritability of 305 day milk yield (0, 02) Correlation between breeding values estimated using test day milk yields and breeding value of 305 day milk yield was found statistically significant (p<0.01) and high level (0.862). In estimation of breeding value for test day milk yields and 305 day milk yield, Spearman and Kendall correlations between rankings of bulls were found 0.853 and 0.662 and statistically significant (p<0.01). According to results of this study, in genetic evaluation of dairy cows, test day milk yields should be used instead of 305 day milk yield. Furthermore, in genetic evaluation of dairy cows, there are advantages for using test day milk yields. Test day milk yields ought to be taken into consideration in early culling and selection of cows for milk yield.
Suleyman cilek and Ali Kaygisiz , 2008. Breeding Value Estimation of Dairy Cattle Using Test Day Milk Yields for Brown Swiss Cows Reared at Ula State Farm. Journal of Animal and Veterinary Advances, 7: 703-706.