Reproductive qualities and the duration of using the cows at lines’ crosses

The purpose of the research was to study the influence of the line crosses on reproductive quality and the duration of economic use of black-and-motley cows in the conditions of breeding reproducers of Omsk Region. The objects of the study were the cows of black-and-motley breed numbering 849 heads. Grouping of animals was carried out taking into account the breeding method by which the animals were obtained. In the cross-section of the lines the period of rearing of repair heifers varied from16.5 to 22.6 months. Repair heifers received from the paternal line of V. B. Idial reached the age of the first insemination from 17.5 to 20.0 months. There was significant advantage in terms of reproduction ofcrosses in which the mothers of cows belonged to the Pabst Governor Factory line. The advantage in precocity was + 1.0...+6.1 months or 6.01-39.96 %, for the duration of service- and indifference-periods of 21-73 days and 7-45 days, respectively. Average age of the retirement of cows in entire study population was 3.06 lactations, but depending on the cross of the parent lines, it varied from 2.2 to 3.8 lactations. The minimum age of retirement was characterized by the cows received from the crossR. Sovering × M. Chieftain, their age was only 2.2 lactation, which was 1.6 lactation or 72.7 % less than that of the cross R. Sovering × P. Governer, which differed in the maximum age of retirement of cows. The duration of productive use of cows obtained from the cross R. Sovering × S. T. Rokit was higher in comparison with the peers by 196-620 days, when leaving the herd at the age of 3.5 lactations.