The effects of replacing monensin with sodium bicarbonate in diets for confined heifers on weight gain (WG), dry matter intake (DMI), feed:gain ratio (FGR) and rumen fermentation parameters were evaluated. Fifity six heifers were utilized (Santa Gertrudis x Braunvieh). Diets were formulated with two levels of concentrate (50% and 80% concentrate) with sodium monensin or sodium bicarbonate. The DMI was higest in heifers with an intake of 80% concentrate. There was not difference when the same concentrate levels were evaluated in relation to the DMI. The heifers at 80% concentrate showed highest WG. There was no significant difference in relation to WG between monensin and bicarbonate treatments and levels concentrate proportions. There were significant effects regarding FGR between treatments. The heifers on 80% concentrate showed lowest FGR. In the evaluation of N-NH3, the highest values were observed, on the whole, at 80:20 diets in relation to 50:50 diets. In the additive use, the monensin on 80:20 diets promoted the highest values of N-NH3 at 1 for 9 hours after feed intake. In the values of ruminal pH, the bicarbonate increased the values on 50:50 at 6 for18 hours after feed intake, in relation to the 80:20 diet. In this case, it was concluded that the use of sodium bicarbonate in diets for confined finishing heifers is a viable option for the replacement of monensin sodium.
beef cattle; performance; buffer; feedlot; ionophore
