Modeling the breeding index of milk producing ability of cows of red cattle breeds

The research findings on modeling the breeding index of milk producing ability of cows of red cattle breeds are discussed. The research was carried out using the BLUP Multitrait AM method based on the databases of 18 breeding farms whose animals together made up the majority of red dairy cattle population in the country. The number of breeding stock in the sample amounted to 12886 heads including cows with lactation completed in 2018-2023: from the first to the fifth lactations. To calculate the index, the selection and genetic parameters of five key indices of milk producing ability were initially determined: milk yield (kg), butterfat yield (kg), milk protein yield (kg), butterfat percentage in milk and protein percentage in milk. Special attention was paid to the indices of butterfat and protein yields since high values of both genetic and phenotypic correlation between these traits and milk yields confirmed their importance for overall milk producing ability. The weight coefficients for each index were determined: for milk yield (kg) - 1, for butterfat yield (kg) - 3, and for milk protein yield (kg) - 3. Next, subindexes for each group were calculated, and then these subindexes were combined into a common selection and economic index taking into account the determined weight coefficients. It is important to note that in order to achieve more accurate results the model may be improved by including additional parameters. In addition, the weight factors may be revised to take into account fluctuations in prices for dairy products and changes in market demand. Thus, the developed breeding index is a dynamic model and may be used to calculate the forecast of the breeding value of cows of red dairy cattle breeds, and for further selection of the best genotypes for breeding.