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چکیده
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The purpose of this study was to investigate the effect of diet nutrient density (energy and protein) on the performance of Holstein cows milked three (3×) or six times (6×) daily in the first 25 days after calving. A total of 20 fresh cows (eight in first lactation and 12 in second lactation) were selected in a factorial 2 × 2 arrangement on the basis of complete stochastic blocks, which were stochastically allocated in experimental groups. The cows were fed two levels of diet density, high (H) and low (L) concentrate from day 1 until day 25 after calving, after which all groups were milked 3 times daily and fed the same diet. Cows were milked three (3×) or six (6×) times daily. Four experimental groups were formed consisting of H3 (high concentrate and 3×), L3 (low concentrate and 3×), H6 (high concentrate and 6×) and L6 (low concentrate and 6×). Milking frequency increased dry matter intake (DMI), milk production, milk fat and milk protein yield, but milk fat or protein content were not affected. Milking frequency also increased non-esterified fatty acids (NEFAs). Diet density on did not affect DMI, milk fat and protein percent and blood metabolites, but it did influence milk production and yield of fat and protein. There was no significant interaction between diet and milking frequency. In conclusion, increasing diet density and milking frequency in early lactation increased milk production
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