336 Anavrin®, Monensin or Both on the Diet of Finishing Steers fed TMR? Effect on Performance and Rumen Fermentation

Abstract

The objective of this was to evaluate the effects on dry matter consumption (DMI), daily gain (DG), feed efficiency (FE) and rumen fermentation of including monensin or an additive composed of essential oils, flavonoids and tannins. (Anavrin) in the diet of fattening steers, studying possible associative effects between them. Thirty steers (12 with 8 mm rumen probes), feeders with TMR diet (ground corn, soybean meal, grass hay, mineral-vitamin concentrate; 65% MS, 12.8% PB, 23% FDN), offer 2.8% of your PC (MS base), were blocked by PC and distributed in 3 treatments (n=10/treatment), adding to the basal diet: 1) 0.033 g of monesin/kg TMR offered: MON', 2) 0.35 g of Anavrin/100 kg BW: 'Anavrin' or 3) both included each at the same dose of 1 and 2 treatments: 'Anavrin® +MON'. The experiment lasted 60 d, and the steers were weighed every 12 d, for 2 consecutive days each time. The DMI was measured individually 3 times over 5 consecutive days, starting on days 20, 34 and 48, by difference offered-rejected for each food. Rumen pH, N-NH 3 and volatile fatty acids (VFA) were measured on days 19, 33 and 47, at 9:30; 13:00; 15:00; 17:00; 19:00; 21;00; 3:00 and 9:30h. Productive behavior (GR and FE) was similar for all treatments, and rumen fermentation was similar for Anavrin and MON. Adding a combination of both additives (Anavrin+MON) leads to a lower DI with respect to Anavrin alone, a lower butyrate concentration than monensin alone, showing associative effects. The percentage of propionic tended to be higher when the combination was added, which should lead to lower methane emissions. Overall, the use of Anavrin led to results similar to those of monensin.