Impactul ritmului parturiției asupra reproducției și producției de lapte la vacile din rasa Holstein

The impact of the calving process (easy, moderate, difficult, very difficult) on the main reproductive indicators (the duration from calving to first insemination, the service period, the number of inseminations per pregnancy, and the calving interval) and cumulative milk production (milk yield per normal lactation of 305 days and total milk fat) in Holstein cows exploited in the pedoclimatic conditions of the Republic of Moldova was studied. The effect of calving ease on reproductive performance and milk production was analyzed using linear regression with calving ease category adjusted as a fixed effect. The frequency of difficult calvings with assistance from the farmer was 3.4% lower, and that of very difficult calvings with veterinary assistance was 0.26% lower in heifers, compared to the situation when male calves were born. In cows with very difficult calving assisted by a veterinarian, the period from calving to first insemination was 24.9 days longer, and the service period was 43.4 days longer, compared to cows with easy calving. Consequently, they required 0.76 more inseminations to achieve pregnancy and had a calving interval 40.5 days longer, compared to unassisted females. Milk losses during normal lactation (305 days) after a veterinary-assisted calving were significant in the first three months of lactation at 1.28 kg/day/head, generating a loss of 1.22 kg/day/head, compared to modern farmer-assisted calving.