Composition of milk protein in cows of different genetic groups

The aim of this research was to study the effect of crossbreeding Finnish Ayrshires with Norwegian Reds in the temperate climate of Ukraine on the content of essential amino acids and their biologi cal value. The study was conducted on a commer cial farm in Poltava region on Finnish Ayrshire cows and their crossbreeds with Norwegian Reds. On the farm, cows are kept loose in an easily assembled building on deep, long-lasting straw bedding. Milk ing takes place twice a day in the milking parlour on a 2×12 «Parallel» unit. Groups of purebred (n=16) and crossbred (n=20) cows of the first lactation were formed for the study. The animals were in the third month of lactation for 74±17 days and were not preg nant. The use of interbreed crossing of Finnish Ayr shires with Norwegian Reds had a positive effect on the protein composition of milk. For the protein of Finnish Ayrshires, the first limiting (lower than the recommended content in the reference protein) ami no acid was methionine + cystine (affects the rate of clot formation during cheesemaking), the content of which was 96.3 %. In the protein of crossbred cows, amino acids in which the rate was less than 100 % were not detected. The most excessive were phenyl alanine + tyrosine – 143.7 % and leucine – 122.1%, which are aromatic amino acids and affect the taste properties of milk. The protein of crossbreds was characterized by a slightly higher total utility coef f icient compared to purebred counterparts (by 12.77 %). Also, the aminogram of the crossbred group was closer to the «ideal». In terms of the three functional groups of amino acids studied, the Finnish Ayrshire and Norwegian Red crosses were slightly superior compared to the purebred Ayrshires. The best protein composition was the milk of the Finnish Ayrshire and Norwegian Red crosses, which gives reason to con sider it more suitable for the production of cheeses and fermented milk products compared to the pure bred counterparts. Key words: dairy cows, breeds, crossbreeding, milk protein, amino acids.