Milk Yield and Milk Fatty Acids from Crossbred F1 Dairy Cows Fed on Tropical Grasses and Supplemented with Different Levels of Concentrate

SIMPLE SUMMARY: The objective of this study was to determine milk fatty acids (FA) from crossbred F1 dairy cows fed on tropical grasses and supplemented with different levels of concentrate. Milk yield and milk composition were not affected while very mild effects were found in milk fatty acids. Overall, this study shows that adding up to 450 g/kg of concentrate to crossbred F1 dairy cows fed on tropical grasses does not have negative effects on milk yield and milk quality. Therefore, under these production conditions, farmers can avoid the use of concentrate, rely on tropical grasses, and reduce feeding costs. ABSTRACT: The objective of this study was to determine milk fatty acids from crossbred F1 dairy cows fed on tropical grasses and supplemented with different levels of concentrate. Twelve dairy cows (50% Holstein × 50% Brahman) with 60 days of lactation grazing tropical grasses were assigned to a Switchback design, with three periods of 15 days with different concentrate levels: 0, 150, 300 and 450 g /kg. Milk samples were obtained on the last five days of each experimental period. Milk yield and milk composition were not affected. Cows fed with 300 g/kg of concentrate had higher contents of C15:0 (p = 0.004), C22:0 (p = 0.031), and C24:0 (p = 0.013). C17:1 cis9 was higher (p = 0.039) with 150 g/kg and lowest with 450 g/kg. C18:1 cis9 was higher (p = 0.042) with 150 g/kg. C18:2n6trans was higher (p = 0.05) with 300 g/kg and lower (p = 0.018) with 450 g/kg. This study shows that adding up to 450 g/kg of concentrate to crossbred F1 dairy cows fed on tropical grasses does not have negative effects on milk yield and milk quality. Therefore, under these production conditions, farmers can rely on tropical grasses and reduce feeding costs.