Polymorphism of the DGAT1 gene and its relationship to milk yield and some chemical properties of milk during the first stage of production in local cows and Holstein cows; a comparative study

Abstract

In present study, 50 dairy cows of the local and Holstein breeds were used (34 local cows and 16 Holsteins). Milk samples were collected from 50 cows once every two weeks from the morning milking (to estimate the daily amount of milk, multiply the amount by 2). One-day test to calculate the daily and monthly milk yield. Samples were taken at a rate of 50 ml for each cow, and the proportions of the main milk components (fat, protein, lactose and non-fat solids) were estimated. Blood samples were drawn from cows for the purpose of DNA extraction. Then the DGAT1 gene was amplified using the primers of the studied piece, which was 411 bp in size. The gene was cut using Taq1 restriction enzyme. The results showed the presence of three genotypes: AA, AK, and KK. In terms of the quantity of daily, weekly, monthly, and first stage milk production, the findings also demonstrated that the genotypes AK and KK of the Holstein breed were superior (P< 0.05) than the two genotypes AA and AK of the local breed. While the genotype AA of the local breed was superior to the genotype AK in terms of daily, weekly, and monthly milk production as well as the first stage, it was also discovered that there is a correlation between the genotypes and the chemical components of milk, as the results showed that the genotype AA was significantly superior (P<0.05) by the percentage of fat in the local breed on the AK and KK genotypes of both breeds.