Agricultural Institute, BG-9700 Shumen, Bulgaria
IVANOVA, T., 2004. Estimation of the breeding value of bulls from the Black and White cattle breed by some traits. Bulg. J. Agric. Sci., 10: 377-382
The objective of this study was to estimate the breeding value of the bulls from the Holstein-Friesian breed by five selection traits. All used bulls from three herds were an object of the study for the period 1976-2002. The BLUP procedure was used to determine the breeding value of the bulls for the most important selection traits - lactation days, milk yield, fat content, butter fat and age of first calving. The sources of variation were: line (a = 1…5), breed (i = 1…2), season (j = 1…4), period (n = 1…6) and sire (m = 1…49). The bulls were ranked on the basis of the traits estimated. The rank correlation coefficients between the traits of milk productivity and the age of first calving were estimated.
The ranking of the bulls had different values for the basic selection traits. The rank correlations had different values. The selection effect will increase if the estimation of the breeding value of the bulls is performed simultaneously by a number of traits.