Relationship of the productivity of first-heifers Holsten with subsequent milk productivity

A study was conducted on the average milk production of Holstein cows for all completed lactations. The relationship between selection traits of Holstein heifers and subsequent milk productivity was studied. The average milk productivity indicators for the first two, first three and first four lactations of Holstein cows, including the cost of milk produced at basic fat content, exceeded the productivity indicators of first calf heifers. The milk yield indicator for the first lactation had a high level of correlation with such average indicators for the first two lactations as: milk yield (0.87), amount of milk fat (0.84) and amount of milk protein (0.87). At the same time, the relationship between milk yield in the first lactation and average milk fat content in the first two lactations was weak (0.25), and the relationship between milk yield and average milk protein content was weak and negative (-0.13). The correlation coefficient between milk yield in the first lactation and average milk yield in the first three lactations was 0.68. There was practically no relationship between milk yield in the first lactation and average milk fat and protein content (-0.07 and 0.04, respectively). The relationship between milk protein content in the first lactation and average milk fat content (-0.92) in the first three lactations was strongly negative. A relationship was found between the milk fat content in the first lactation and the average milk fat content in the first two (0.55), first three (0.34) and first four (0.32) lactations. The positive average values of the coefficients make it possible to include the milk fat content indicator for the first lactation among the traits to be selected when selecting according to the milk fat content indicator for subsequent lactations.