Всероссийский научно-исследовательский институт физиологии, биохимии и питания животных – филиал Федерального государственного бюджетного научного учреждения «Федеральный научный центр животноводства – ВИЖ имени академика Л.К. Эрнста»
ABSTRACT. Study of blood chemistry was performed on three groups of cows aged 3 years and older, 10 cows each, of different breeds: 1) Yaroslavl purebred, 2) Canadian Holstein, 3) Yaroslavl holstenized (Mikhailovsk type), at different stages of the reproductive cycle: calved (15 days after calving) in mid-lactation (4-5 mo.) and during dry period. In fresh Holstein cows, the level of calcium and inorganic phosphorus in serum was significantly lower compared with the Yaroslavl breed (P<0.05), indicating a predisposition of Holstein cows to violations of calcium-phosphorus metabolism. Milk yield per lactation in groups 1-3 was 5028±220, 6316±376 and 6719±419 кg, milk protein − 165±10, 190±11 and 207±16 kg respectively. The average length of productive life of cows was in group 1 – 2.2, in the 2 and 3 groups – 4.5 and 4.4 lactations. The main reasons for the culling of Holstein cows were diseases of extremities, digestive and reproductive system – 27.7; 24.1 and 13.4%, in Yaroslavl and Mikhailovsk type cows – gynecologic diseases and infertility, diseases of extremities and udder – 24.4; 8.9; 20 and 20; 14.5 and 10.3% respectively. The data obtained suggest that Yaroslavl cattle and animals of Mikhailovsk type are superior to imported Canadian Holstein cattle for clinical and physiological parameters and longevity in the conditions of Yaroslavl region of Russian Federation. In order to improve animal production and breeding, it must search for specific symptom complexes and diagnostic tests for selection of animals with increased viability.
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