Effects of replacing steam-flaked corn with increasing levels of malted barley in a finishing ration on feed intake, growth performance, and enteric methane emissions of beef steers

The objective of this experiment was to determine the effects of feeding malted barley (MB) as a source of exogenous α-amylase to finishing beef steers on growth performance and methane (CH4) emissions. Forty crossbred yearling steers (initial BW = 522 ± 31.4 kg) were used in a randomized complete block design. Steers were blocked by BW and assigned to 1 of 2 pens, each containing an automated head chamber system (GreenFeed; C-Lock Inc., Rapid City, SD) and individual feed bunks with Calan gates (American Calan, Northwood, NH). Animals were then randomized to receive finishing diets formulated to be iso-nitrogenous and iso-energetic but contain (DM basis) either 0% MB (0MB), 10% MB (10MB), or 20% MB (20MB). There was no effect of MB inclusion on DMI or ADG (P ≥ 0.20); however, there was a linear decrease (P ≤ 0.02) in feed efficiency and DM digestibility with increasing MB inclusion. Furthermore, MB inclusion resulted in a quadratic response (P = 0.05), where CH4 production (g of CH4/d) was increased by the MB diets. Increasing MB did not affect CH4 yield (P ≥ 0.13; g of CH4/kg of DMI), but there was a tendency for a linear increase in emission intensity (g of CH4/kg of ADG; P = 0.09). We speculate that the decreased DM digestibility and feed efficiency were caused by the MB being fed unprocessed—highlighting the need for further research where MB is fed processed (e.g., dry rolled).