Effect of rumen modifier management on feedlot performance and carcass attributes of steers

Abstract

Antibiotic rumen modifiers (ARMs) have been routinely included in feedlot rations to improve rumen function and nitrogen retention (Elsasser 1984), but, with the exception of laidlomycin, no new ARMs are being registered. Alternative management strategies for existing ARMs in feedlot finisher rations have been studied to improve productivity and efficiency. Advantages in average daily gain (ADG) and gain to feed of 4.8% and 2.7%, respectively, have been found in Canada with the daily rotation of monensin and lasalocid compared to monensin alone in steers on finisher rations (Shreck et al. 2016). However, few studies have examined the effect of ARM strategies from feedlot arrival to exit, or compared individual ARM with multiple ARMs in daily rotation over the full feeding period. This study sought to quantify how changes in ARM management might deliver growth, and carcass advantages to the Australian feedlot industry.