307 Effects of Incorporating Malted Barley in a Finishing Ration on Intake, Performance, and Enteric Methane Emission of Beef Steers

Abstract Incorporations of malted barley (MB), as an exogenous source of α-amylase, demonstrated the potential to reduce methane (CH4) emissions in an in vitro experiment. However, this finding had not been confirmed in vivo. Forty-two mixed breed (predominately Bos taurus) influenced yearling steers (initial BW = 521.7 ± 31.4 kg) were used in a randomized complete block design experiment. Steers were blocked by BW and assigned to one of two pens, each containing an automated head chamber system (GreenFeed; C-Lock Inc., Rapid City, SD). Each steer was assigned to an individual feed bunk with Calan gates (American Calan, Northwood, NH) and fed a finishing ration for 92 days. Within each block, animals were assigned to 1 of 3 treatments based on MB inclusion level (DM basis): 0% MB (CON), 10% MB (10MB), or 20% MB (20MB), which were formulated to be iso-nitrogenous and energetic. All data were analyzed using orthogonal polynomial contrasts. There was no significant effect of MB inclusion on DMI or ADG (P ≥ 0.20); however, due to numerical differences, there was a linear reduction (P = 0.02) in feed efficiency with increasing MB inclusion. Further, there was a significant (P = 0.05) quadratic increase in CH4 production (g CH4/d) with increasing MB inclusion, such that MB fed steers had, on average, 7% greater CH4 emissions compared with the CON steers. Increasing MB did not affect CH4 yield (P ≥ 0.13; g CH4/kg DMI), but there was a tendency for a linear increase in emission intensity (g CH4/kg ADG; P = 0.09) with increasing MB inclusion. We speculate that the discrepancy between the previous in vitro experiment and the current experiment may be related to grain processing (diets ground for in vitro vs. MB not processed in current experiment); highlighting the need for further research.