Significance of breeding value indicators for prediction of milk yield

Abstract

A comparative assessment of the significance of various indicators of the breeding value of breeding bulls for predicting milk yield in the highly productive herd of the farm economy "Alfa" was carried out. The milk yield of cows, whose bulls-fathers were evaluated in Ukraine and abroad, was studied. It was established that in the period from 2009 to 2014, the milk yield of first-calf heifers increased by 23.9 % and reached 5894.3 kg. Accordingly, during the specified period, most of the quantitative indicators of the breeding value and milk productivity of the bulls' daughters also increased: the breeding value of the parent bulls in terms of milk yield increased from +245.3 kg in 2009 to +540.4 kg in 2014; the breeding value of parent bulls in terms of the total amount of milk fat per lactation increased from +10.2 kg to +29.7 kg. A correlation analysis of the relationships between various indicators of breeding value of parent bulls and the milk yield of their daughters was carried out. It was established that the actual milk yield of first-calf heifers in FE "Alfa" most (correlation coefficients r higher than 0.8) and most significantly (p<0.001) depended on the average milk yield and amount of milk fat yield of bull's daughters in the herds where the breeding value of these bulls was evaluated. The breeding value of the sire bulls by the amount of milk fat yield was also characterized by high (r=0.675) and significant (p<0.01) relationship with the actual milk yield of the first-calf heifers (daughters of these sires). The variance analysis of the influence of the breeding value estimation method of breeder bulls (BV, ETA, ZW, DRV, RPC) on the actual milk yield of their daughters during the first lactation established that this influence was significant (p=0.001), and the power of influence was η2=0,59. Significant differences were mostly observed between milk yields of first-calf heifers whose parent bulls were evaluated abroad and in Ukraine. The biggest difference in terms of actual milk yield was revealed between the daughters of bulls evaluated by the ETA method (Canada) and by the "daughter-of-the-same-age (DRV)" method (Ukraine). This difference was 2640 kg of milk (p<0.01) in favor of firstcalf heifers from Canadian bulls. Key words: breeding bulls, breeding value, milk productivity, daughters of bulls, milk yield, selection index, evaluation method.