Productivity of Holstein cows with early insemination of heifers

The age at first insemination is a critical factor influencing the duration of the non productive period, subsequent milk yield, and reproductive performance of cows. Accordingly, the study aimed to determine the impact of early insemination age on cows’ milk productivity and reproductive capacity. The research was conducted using Holstein cows and carried out at Rozhnivka-Agro LLC, located in the Ichnia District of Chernihiv Region. The findings revealed that the live weight of the experimental animals at first calving showed no significant deviations, remaining within a 3.3% range. During the first lactation, the shortest service period was observed in animals inseminated at 13 months of age, with differences of 4.5 (Group I ↓) and 3.9 days (Group III ↓). The highest insemination index, reaching 3.1, was recorded across all experimental groups during the third lactation. The highest insemination index of 3.1 across all experimental groups was observed during the third lactation. Milk productivity was analysed daily by lactation months, considering milk fat and protein yields. The results indicated no significant differences in milk yield during the first lactation across all groups. However, during the second lactation, a general upward trend in milk yield was noted in all groups. Notably, cows inseminated at 13 months of age exhibited 4% and 1% higher milk productivity compared to Groups I and III, respectively. The peak milk yield across all groups occurred during the third lactation. The lowest milk yield was recorded in cows inseminated early (at 12 months), with differences of 7.8% (Group II ↑) and 6.9% (Group III ↑). Regarding lactation-specific fat content, Group II (13 months) demonstrated higher fat content during the third lactation by 0.23%, 0.13%, and 0.05% compared to the first, second, and fourth lactations, respectively. No significant differences were observed in milk protein content, which ranged between 3.20% and 3.23%. Thus, reducing the age of first insemination can enhance the economic utilisation of animals without compromising their reproductive performance or adversely affecting subsequent milk productivity