The objectives of this study were to evaluate consumption, ruminal parameters and milk production of F1 Holstein x Zebu milking cows fed nitrogenated supplements with or without monensin added to the silage. Cows with 21 days on milk and producing initially 19.2kg of milk/day were distributed in a 5X5 Latin square design with three replicates per treatment. The treatments (T) were: 1- concentrate fed during the milking time and corn silage fed after milking (C.SM); 2- C.SM + nitromineral(NM) (C.SMNM); 3- C.SM + nitroproteico (NP) (C.SMNP); 4- C.SMNM + monensin (C.SMNM+MO) e 5- C.SMNP + monensin (C.SMNP+MO). The addition of NP e NM to the T C.SM increased the DMI when compared to C.SM (P<0.05). The addition of monensin did not change the DMI (P>0,05). The protein supplementation did not alter acetate (P>0,05), but increased propionate and butyrate concentrations. (P<0.05) The N-NH3 concentration increased (P<0.05) only in T C.SMNM (P<0.05). The addition of monensin to T C.SMNP decreased propionate and butyrate concentrations (P<0.05) related to T C.SMNP. The milk production was greater in the C.SMNP treatments than T C.SM (P<0.05). Cows in T C.SM produced milk more efficiently than cows fed C.SMNM (P<0.05), but did not differ from the others.
consumption; ruminal parameters; F1 Holstein-Zebu; monensin; protein supplementation
