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

Authors: Beck, Matthew - Matt; PROCTOR, JARRET - Texas A&M University; KASUSKE, ZACHERY - Former ARS Employee; SMITH, JASON - Texas A&M Agrilife; GOUVÊA, VINICIUS - Texas A&M Agrilife; LOCKARD, CATHERINE - Former ARS Employee; MIN, BYENG - Former ARS Employee; Brauer, David

Submitted to: Applied Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2023
Publication Date: 12/1/2023
Citation: Beck, M.R., Proctor, J.A., Kasuske, Z., Smith, J.K., Gouvêa, V.N., Lockard, C.L., Min, B., Brauer, D.K. 2023. 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. Applied Animal Science. 39(6):525-534. https://doi.org/10.15232/aas.2023-02435.
DOI: https://doi.org/10.15232/aas.2023-02435

Interpretive Summary: Reducing methane (CH4) emissions is the number one means to limit the effects of climate change in the short term. Enteric CH4 accounts for 27% of U.S. CH4 emissions and represents the largest contributor to U.S. CH4 emissions. Accordingly, enteric CH4 is an important source of greenhouse gases that must be reduced. Malted barley is a natural source of a-amylase, which may alter ruminal fermentation and subsequently reduce CH4 production when fed to cattle. However, the effects of feeding malted barley to finishing cattle on enteric CH4¬ and animal production is unknown. To answer this question, researchers from ARS (Bushland, TX); Texas A&M University; and Texas A&M AgriLife conducted a feeding trial to assess the efficacy of malted barley to reduce enteric CH4 emissions. It was determined that enteric CH4 emissions increased with increasing malted barley inclusion in the diet. Furthermore, there was also a linear reduction in feed conversion efficiency with increasing malted barley inclusion. Based on these results it was concluded that feeding malted barley is not a recommended strategy to reduce enteric CH4.

Technical Abstract: Objective: The objective of this experiment was to determine the effects of feeding malted barley (MB) as a source of exogenous a-amylase to finishing beef steers on performance and methane (CH4) emissions. Materials and Methods: Forty-two mixed breed, predominately Bos taurus influenced yearling steers (initial BW = 522 ± 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) and individual feed bunks with Calan gates (American Calan, Northwood, NH). Animals were then randomized within block to receive finishing diets for 92 days formulated to be iso-nitrogenous and iso-energetic but contain (dry matter basis) either 0% MB (0MB), 10% MB (10MB), or 20% MB (20MB). Results and Discussion: There was no significant effect of MB inclusion on dry matter intake (DMI) or average daily gain (ADG; P = 0.20); however, due to numerical differences, there was a linear reduction (P = 0.02) in feed efficiency and dry matter digestibility (DMD) with increasing MB inclusion. Further, increasing MB inclusion resulted in a significant (P = 0.05) quadratic increase in CH4 production (g CH4/d). 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. Implications and Applications: We speculate that the reduced DMD and feed efficiency are due to the MB being fed unprocessed – highlighting the need for further research where MB is fed processed (e.g., dry rolled).