Estimation of the breeding value and ranking of holstein-friesian bulls for milk production traits

Abstract

The aim of this research was to estimate breeding value and rank of Holstein – Friesian bulls for milk production traits. The analysis included 433 daughters of 10 bulls, calving for the first time in the period from 2007 to 2014, on 6 dairy farms of the Agricultural Corporation Belgrade AD. Fixed factors included in the model were the effects of the farm, genetic groups and calving season, and as a random factor the impact of the bull sire. The observed milk traits on the basis of which the breeding values were calculated were the milk yield (kg), the 4% fat-corrected milk yield (kg), the fat content (%), the fat yield (kg), the protein content (%) and the protein yield (kg). Sires were ranked according to abovementioned milk traits and Spearman’s Rank correlation was used to determine association between the ranks of the sires. According to the breeding values calculated by using the Best Linear Unbiased Prediction (BLUP) method, the sire 1676 was best ranked for the traits: milk yield (+363,88 kg), fat yield (+13,57 kg) and protein yield (+15,55 kg), relative to the average of daughters. The effect of the calving season showed a high significance (p<0.01) for the following traits: milk yield, 4% fat-corrected milk yield, fat yield and protein yield while there was no significant effect for other traits (p>0.05). Statistically very significant correlations between sire estimated breeding values for fat content and the protein content of 0,84 (p <0,01) and between the fat yield and the protein yield of 0,96 (p<0,01) was determined by the Spearman coefficient of correlation.