The effect of season of calving on milk production and milk quality

The study was performed on a herd of purebred and crossbred with the Holstein breed of black-motley cattle in OAO "Oryol black soil" in the Orel region. The productivity of Holsteins crossbred animals compared to purebred black-and-white animals was higher regardless of the calving season. High milk yield in complete lactation was obtained from cows, parturient during the winter months. Cows calving in winter and spring months had uniform type of lactation curves. The largest number of somatic cells in milk was in the spring, when the animals lactate in the most extreme conditions, respectively, in groups 237 and 252 thousand/cm3. Less somatic cells in milk was in summer, the difference compared to spring were 89% and 99 thousand/cm3 (P3 (P3 (P≤0.001). High bacterial content of milk noted in spring, in purebred cows amounted to 458 thousand/cm3, in hybrid - 511 thousand/cm3. Relative to other seasons of calving low bacterial content of the milk was from cows calving in winter - 368 and 380 thousand/cm3, respectively. The difference with the spring period was 90 and 131 thousand/cm3 (P3 (P