The association of productive and reproductive traits in cows of genealogical line Refl ection Sovereign in different lactations

Abstract

In order to effectively carry out breeding work in dairy cattle, it is necessary to take into account the association between economically useful traits in cows. The magnitude of the positive and negative correlation varies depending on the direction of selection, feeding conditions and housing of animals. The purpose of the work was to study the association between productive and reproductive traits in cows of the genealogical line Refl ection Sovereign 198998 in diff erent lactations. It was found as a result of the conducted research that the majority of cows belonging to the genealogical line Refl ection Sovereign 198998 (64,0 %) were young cows in the fi rst and second lactations. Cows with mature (third) lactation had the highest milk yield. Their milk yield was 8834±288,54 kg, which was 1555 kg or 21,4 % more than that of the fi rst-calf heifers. There was a natural increase in milk yield from the first lactation to mature age, and then a gradual decrease until the end of the use of animals. The difference in the value of milk yield for adjacent lactations was insignifi cant. The average daily milk yields of cows for diff erent lactations were quite high and range from 15,0 to 30,0 kg or more. There was a direct association between milk yield for the entire lactation and the duration of the open day’s period. The correlation coeffi cients between these traits were from +0,49 to +0,85 in cows of the genealogical line Refl ection Sovereign 198998, which indicates an average and high correlation of traits. This circumstance should be taken into account, because excessive lengthening of lactation leads to a decrease in the level of reproduction in the herd. The increase in milk yield positively correlated with the mass fraction of fat in milk and the yield of milk fat during lactation.