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

Objective

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.

Materials and Methods

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).

Results and Discussion

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).

Implications and Applications

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).