Productive longevity of white-and-black cows of different genotypes CSN3 and DGAT1

Abstract

The article studies the duration of use and life-long productivity black-motley breed cows with different allelic variants of the kappa-casein and diacylglycerol O-acyltransferase genes. The research consists the data study on cows dropped out the herd during 2012–2016 in the Dusym LLC of Atninsky District in the Republic of Tatarstan. The cows were previously genotyped for CSN3 and DGAT1. The herd of black-and-white cattle consisted the genotypes CSN3 AA and DGAT1 AK with a frequency of 60.9 and 53.5 % and less often CSN3 BB and DGAT1 KK – 4.0 and 6.3 %. Moreover, the frequency of occurrence of the desired B allele of the CSN3 gene was 0.22, and the K allele of DGAT1 was 0.33. Cows with the CSN3 AB genotype reliably surpass animals with the CSN3 AA genotype in the duration of use by 0.39 lactations (P <0.05), life-long milk yield by 2401 kg of milk (P <0.05), and the amount of milk fat by 90 kg (P <0.05), mass fraction of protein in milk – by 0.04 % (P <0.01), the amount of milk protein – by 83 kg (P <0.05). Animals with the DGAT1 KK genotype also have an excess over other groups of cows in terms of productive longevity, but the difference is significant only in fat milk (P <0.01–0.001).