Candidate genes for control of cattle milk production traits

The analysis of the frequencies of occurrence of alleles and genoypes by the genes encoding the milk proteins (kappa-casein, casein alpha 1S, and beta-lactoglobulin) and two key enzymes of the lipid synthesis (acil-CoA diacilglicerol aciltransferaza-1 and stearoyl-CoA desaturase-1) in dairy (Black-and-White Holsteinized and Ayrshire breeds) and beef (Aberdeen-Angus and Kalmyk breeds) cattle has been performed. According to the literature and our own data sets, it was ascertained that the allelic variants of candidate genes participating in the metabolic processes and defining their functional specificity to control the important economic traits, including the milk production, are not reliable bioindicators required for the early prediction in this case. However, the allelic variants of the genes, such as kappa-casein and stearoyl-CoA desaturase-1, may be used to predict the quality but not the quantity of milk, for instance, the size of micellae in milk, the suitability of milk for firm cheese production, and the enrichment of products with unsaturated fatty acids.