INFLUENCE OF CALVING SEASON OF COWS ON THEIR PRODUCTIVITY UNDER ORGANIC AND CONVENTIONAL MILK PRODUCTION

Abstract

The aim of the research was to study the impact of the first calving season of Simmental cows on their future milk productivity and reproductive capacity in conditions of both organic and conventional milk production.
 Research materials and methods. The research was conducted in Simmental breed herds of PE "Galex-Agro" (organic milk production, n = 272) and STOV "Myroslavel-Agro" (conventional milk production, n = 120) in the Zviahel district of Zhytomyr region, Ukraine. First-calving cows in the two farms were categorized into four groups based on the calving season: Group I – Winter (n = 83 and 42 cows in PE "Galex-Agro" and STOV "Myroslavel-Agro" respectively); Group II – Spring (59 and 26);Group III (45 and 12); Group IV (85 and 40 cows).
 Research results. First-calving cows in organic production demonstrated a higher expression of quantitative traits of milk productivity, regardless of the calving season, compared to their counterparts in conventional conditions, albeit with slightly lower qualitative traits. However, statistically significant differences were found only in 305-day milk yield between autumn-calving cows in favor of first-calving cows from PE "Galex-Agro."
 It is worth noting that, in both farms, the first calving in the autumn season was found to be the most favorable, while the summer season was the least favorable, which provides grounds for planning calving in the autumn period. Our research results indicate that animals under organic management, regardless of the calving season, exhibited statistically significantly (P < 0.01–0.001) older age at first calving and longer calving intervals. No statistically significant intergroup differences were found in other reproductive traits.
 The season of first calving in both organic and conventional milk production conditions accounted for 0.3 to 4.7% and 0.2 to 3.3% of the total phenotypic variability in milk productivity traits, as well as 1.0 to 2.9% and 0.6 to 2.5% of the reproductive capacity. Statistically significant effects of the calving season were only observed in PE "Galex-Agro" and exclusively on productivity traits, including lactation duration (3.2%), 305-day milk yield (4.3%), milk fat content (4.7%), milk protein content (4.3%), milk fat, and protein content (4.7%), as well as the duration of dry period (2.9%) (P < 0.05–0.001).
 Conclusion. Our research results highlight the importance for specialists in both farms to pay attention to the seasonality of first calving in cows and, if possible, take these aspects into account when planning breeding and technological measures in the farms.