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Received: February 18, 2026

Revised: March 2, 2026

Published: March 30, 2026

 

The study analyzes the influence of non-genetic factors on the reproductive qualities of Holstein cows. The material consisted of record data of cows (n = 644 heads) raised at LLC «Promin» (Mykolaiv region).

The study established a statistically significant effect of the year of conception on the age of first-calf heifers at conception (P<0.001). The highest age at conception was observed in 2014 – 914.8 days, while in 2020-2022 it was significantly lower – 766.0-775.3 days. Similarly, the year of conception significantly influenced the number of services (P<0.001): the maximum value was recorded in 2017 – 2.46, the minimum ones – in 2018 and 2021 – 1.59 and 1.59, respectively.

The month of conception had a statistically significant effect on the age of first-calf heifers at conception (P=0.010), as well as on the pregnancy duration (P=0.020). The lowest age at conception was observed in December, August, and October, and the maximum one was in February. The shortest pregnancy duration was recorded in cows calving in March and January, and the maximum one was in June, May, and September.

The number of services until conception significantly influenced the age of first-calf heifers at conception and the second calving (P<0.001), as well as the duration of the service period (P<0.001). At the same time, the pregnancy duration remained stable (275.0-277.0 days, P=0.935), and the dry period fluctuated within 55.0-62.4 days without significant influence (P=0.369).

The year and month of calving significantly influenced the duration of the dry period (P=0.034-0.009) and calving intervals (P<0.001-0.017).

 

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