Indicators of age variability of productive and reproductive qualities of daughters of red-moiled Holsteen breed bulls

The article presents the results of studies on 494 completed lactation cows. The purpose of the research is to study the main indicators of age variability in the daughters of the bulls Gir 1883, Grilyazh 6977, Kulon 1237 of the red-motley Holstein breed. The objectives are to conduct a sample of daughters of bulls Gir 1883, Grilyazh 6977, Kulon 1237; create groups of cows by lactation; carry out mathematical processing of the results obtained according to four indicators (milk yield for the entire lactation, milk yield for the first 240-305 days of lactation, duration of the intercalving period, duration of the service period); conduct a comparative analysis of the results obtained. The average milk yield for the entire lactation of the daughters of bulls Gir 1883, Grilyazh 6977, Kulon 1237 for all lactations is: 5731.4 kg; 6320.4 kg and 5966.7 kg, respectively. In the daughters of the bull Gir 1883, the average milk production tended to increase with each lactation. The same dynamics in average milk productivity over 240-305 days is observed in the daughters of the bull Grilyazh 6977. The daughters of the bull Kulon 1237 show a stable increase in milk productivity up to the fourth lactation inclusive, and in the fifth lactation there is a slight decrease Analysis of the results of studies of the duration of the intercalving period for daughters of bulls manufacturers Gir 1883, Grilyazh 6977 and Kulon 1237 show that after the first calving the difference in MOP is insignificant - 5,6 days. The highest average duration of the service period was observed in the daughters of all three bulls after the first and second calving. Further, with age, this indicator tends to decrease.