Productive and reproductive indices of Jersey cows of different origin

Abstract

The research findings on the influence of the line affiliation of Jersey cows on their productive and reproductive qualities in the OOO Mir in the Republic of Tatarstan from 2023 through 2025 are discussed. The research targets were first-calf heifers of three lines: Advanger Sleptng Tester (Group I), Glenmors (Group 2) and Secret Signal Observer (Group 3), 15 cows in each group. The management conditions, milk producing ability, milk physical and chemical composition and reproductive abilities were evaluated. All animals were managed under the same conditions during the research period. The farm of the OOO Mir uses a loose-box cow management technology, and year-round stall barn housing system. It was found that the highest milk yield for 305 days of lactation obtained from the first-calf heifers of the Glenmors line was 7960 kg, which was by 463 kg more than in Group 1 (P ≥ 0.99). The milk of Groups 2 and 3 was characterized by a high solids content level, nonfat milk solids and protein. The high protein content in milk of Group 3 was 4.31% - significantly higher than that in Group 1. The highest butterfat content (5.23%) was in the milk of Group 1. In terms of the reproductive qualities of the first-calf heifers, the Glenmors line also had an advantage over its Group 1 counterparts: the youngest age of the first calving (22.1 months), high percent conceptions after the first insemination (71.3%), and a low insemination index. The heifers obtained from Glenmors line cows were characterized by a higher live weight at 6 months (140.2 kg) and growth rate.