Analysis of correlation of indexes of the milk productivity for the cows of Ayrshire breed of breeding farm of the Leningrad area
In this article, the analysis of between such breeding signs as a yield of milk, the mass fraction of fat and protein, the amount of milk fat and protein for 305 days for 8 lactations for the cows of Ayrshire breed. All the of the appraised animals made 815 heads. Were calculated and studied mean values of all signs, range between maximal and minimum values, standard deviation. The mean values % of fat and % protein was maximal in the first and last to the lactation, and in other lactations insignificantly, so that on the diagrams a trend line is horizontal. The middle indexes of the amount of albumen and fat had a tendency to constancy and insignificantly increased to the last lactations, that it is related to the increase in the yield of milk to the last lactation. Standard deviation the fat mass fraction was 0.05; the protein mass fraction was 0.06; the amount of milk fat 12.2; the amount of milk albumen 6,8; that shows homogeneity of meanings on these signs. Between the mass fraction of fat and the mass fraction of protein, the correlation was r = 0.3; between yield of milk and mass fraction of fat, the correlation was r = -0.2; between yield of milk and the mass fraction of protein r = -0.3. A weak positive or negative correlation was observed in all lactations. Genetic correlation between the amount of milk fat and amount of suckling albumen, by the yield of milk and amount of suckling albumen, by the yield of milk and amount of suckling fat was positive r=0,9, because these attributes are linked through milk. To illustrate the changes in lactation parameters and compare them, diagrams were constructed. It can be concluded on the results of the work done that the selection of cattle in this breeding center was carried out simultaneously by yield of milk, milk fat and milk protein and was progressive, which led to a high productivity of animals up to 8 lactations.