Comparative assessment of milk productivity of cows of different genotypes

The improvement of cattle of the black-mottled and Kholmogorsky breeds is carried out by the method of purebred breeding with the use of Holstein bulls of the black-mottled breed in reproduction. Analysis of indicators of dairy productivity of cows has shown that with an increase in blood supply for the Holstein breed, milk yield increases significantly. A comparison of milk yield for the last completed lactation showed that cows of a black-and-white breed with a blood ratio of more than 87.5% for the Holstein breed have an advantage (+1026 kg) compared to purebred Holsteins. The cows of the Kholmogorsky breed are inferior to Holsteins (-359 kg). The mass fraction of fat in the milk of Holstein cows was lower in both I and II lactation compared to the indicators of animals of Kholmogorsky and black-and-white breeds with a blood content of more than 87.5%, and was in the range of 3.88-3.93%. The amount of protein in milk is higher in black-and-white cows in both I and II lactation compared to Holstein cows by 0.04%. The correlation analysis showed that in the studied herds, the main characteristics of cows had negative relationships. Thus, milk yield in cows for 305 days of lactation and fat content in milk was r = -0.175, r= -0.176, r = -0.276, respectively, in Holstein, Kholmogorskaya and black-and-white breeds. A negative relationship of mother-daughter milk yield (r= - 0.034), % of mother-daughter fat (r= - 0.033) was obtained in Holstein cows. Positive correlation of mother-daughter milk yield (+ 0.170; +0.396) percentage of fat, mother-daughter (+0.015;+0.116) is observed in animals of Kholmogorsky and black-and-white breeds.