INFLUENCE OF YEAR AND SEASON ON MILK PRODUCTIVITY OF COWS

Introduction. Numerous studies of domestic scientists testify to the sometimes significant, but multidirectional influence year and season calving birth on formation milk productivity other economically useful traits. In our previous studies, it was established that at population level, among mentioned environmental factors, most significant phenotypic variability first-calf heifers is caused by herd (15–22%), first (4.7–12%) (4.2–12%), lowest (0.05–0.2%) (1.5–2.1%). A number researchers report a higher smaller one especially heifers. opinion, manifestation signs in different herds influenced levels breeding feeding, technological solutions cow keeping milking systems. Research materials methods. The research carried out farms Ukrainian Red dairy cattle LLC "Nova Niva" Donetsk region. electronic information database DCMS ORSEK format as October 11, 2021 were used. controlled animals, intensity growth live weight growing periods up half years age, 18 months, age calving, length service period, coefficient reproductive ability between second carvings, fertility output fat protein for 305 days three lactation. results. On average, during entire accounting level rearing ensured average daily gains almost 600 g, 12 months – more than 550 g. Thus, practically met standard breed. reached 27.9 which corresponded optimal recommendations time (27 months). general, under control characterized relatively low ability. duration period 72 or 90% longer optimum (80 days). Univariate variance analysis an equal share factors studied characteristics cows. determines from 12.6 68.6% total variability, 12.5 70.4% with high degree significance. factor has 1.5–2 times greater old 12–18 months. 10% calving. (0.1–2.3%) (0.2–2.7) exerts much investigated seasonal turned be somewhat higher. productivity, fluctuations conditions show low, reliable only During older lactations, this effect leveled off unreliable statistical cases, intergroup differentiation impact cultivation chronologically naturally climatically economic years, stable feeding cows over years. Correlation direct relationship delivery heifer increase 39.3 ± 1.51% (P < 0.001), six 14.4 1.63% 31.4 1.56% 0.001) 22.4 1.60%, confirms assumptions. Undoubtedly, cannot improvement conditions. accounted genetic herd, particular, conditional blood introduced into improving Holstein breed 25.3 87.5%. terms intensity, autumn had advantage, exceeded counterparts spring 22 2.4 kg 6.4% 0.001). This resulted younger (by 49 5.6 5.9%, P According calved summer slight advantage analogues 2.6 6.3% according 0.001. animals winter 42 5.9 5.0% 0.001 compared calving). Cows distinguished better yield lactation, 203 57.5 3.0% Conclusions. growth, cows, significance (0.2–2.7%) comparison group averages confirmed significantly development analysis.