Effects of a blend of cinnamaldehyde-eugenol and capsicum (Xtract® Ruminant 7065) and ionophore on performance of finishing Holstein steers and on characteristics of ruminal and total tract digestion

Abstract

Our objective was to evaluate the interaction of supplemental essential oils (EO) and monensin (MON) on performance and digestion. Two levels of EO (0 vs 0.011% Xtract®) and two levels of MON (0 vs 33 mg/kg) were evaluated in a 2 × 2 factorial arrangement. Treatment effects on 216-d growth performance were evaluated in 96 Holstein steers. Supplemental MON enhanced (P ≤ 0.05) ADG, DMI and gain efficiency. Without EO, MON improved (P < 0.05) gain efficiency and dietary NE. However, in diets with both EO and MON, gain efficiency and dietary NE were not different from non-supplemented diets (interaction, P < 0.10). Treatment effects on characteristics of digestion were evaluated using four cannulated steers. Ruminal digestion of OM and N were greater for MON alone. Ruminal digestion of OM and N were similar for EO-alone vs MON-alone, but not by the combination of the two (interaction P ≤ 0.02). Supplemental MON enhanced (P ≤ 0.02) total tract digestion of OM and N. We conclude that supplemental EO-alone or MON-alone may enhance gain efficiency and NE value of the diet. However, effects are negated when fed in combination. Treatment effects on performance are consistent with digestion measures.