Effect of different roughages sources on performance, milk composition, fatty acid profile, and milk cholesterol content of feedlot feed crossbred cows (Holstein × Zebu).

Abstract

The aim of the study was to evaluate the effect of different forage sources in diets for feedlot dairy cows and their implications on production, composition, fatty acid profile, and milk cholesterol content. Nine Holstein × Zebu crossbred cows were distributed in three 3 × 3 Latin squares, in three periods of 21days each, and three diets: elephant grass silage + concentrate, briquette from Brachiaria + concentrate, and sugarcane + concentrate. Elephant grass silage resulted in lower milk production and milk protein content. Cows fed elephant grass silage had lower concentrations of the saturated fatty acids C10:0, C11:0, C12:0, and C15:0 in the milk and higher of the unsaturated fatty acids C15:1, C16:1, C18:1n-9t, C18:1n-9c, C18:3n-6, CLAc9t11, and CLAt10c12 in relation to the other diets. Data were analyzed using the GLM procedure of the Statistical Analysis System (SAS) and the means were compared by the Tukey's test (P = 0.05). It is recommended to use the briquette from Brachiaria as a forage source for lactating cows, since it led to higher milk yield. On the other hand, the use of elephant grass silage as a forage source is recommended if the farmer is paid for milk with higher concentration of monounsaturated and polyunsaturated (CLA) fatty acids, which exerts beneficial effects on human health.