October 25, 2018

Interpretive Summary: Effects of reductive acetogenic bacteria and lauric acid on in vivo ruminal fermentation, microbial populations, and methane mitigation in Hanwoo steers in South Korea

Interpretive Summary: Effects of reductive acetogenic bacteria and lauric acid on in vivo ruminal fermentation, microbial populations, and methane mitigation in Hanwoo steers in South Korea.

By: Anne Wallace

Reducing methane (CH4) emissions in livestock is an important area of animal science research. Previous studies have examined the effects of diet on the production of greenhouse gasses in ruminant animals. In this October 2018 Journal of Animal Science study, researchers looked at how Acetogenic bacteria and lauric acid (LA) supplemented feed affected CH4 production in Hanwoo steers. They also evaluated rumen microbial population and their metabolic byproducts.

Acetogens are anaerobic bacteria that use hydrogen to produce acetate as a metabolic byproduct. Lauric acid is a saturated medium-chain fatty acid in which previous studies have indicated may reduce the production of microbial CH4.

The Acetogen probiotics (AP) used in this study were related to the Proteiniphilum acetatigenes GA03 strain. A total of four Hanwoo steers were used. Steers were fed a control diet (CON) with basal feed, LA diet (T1), AP diet (T2), and a mixed diet with LA and AP (T3) for 15 days plus another 6 days. The experimental period took place in the latter. Digesta was collected from fitted cannula ports, starting on the experimental feeding day. Rumen microbiota and volatile fatty acids were measured by real-time PCR and Nuclear Magnetic Resonance, respectively.  

Results indicated that six hours after feed was administered, total VFA, acetate, and propionate concentration was significantly increased in the T1 treatment compared to T2, T3 and CON. The production of CH4 was significantly decreased in T1 and T3, and slightly decreased in T2, when compared to CON. Methanogen populations were reduced in all treatments compared to CON.

The results of this study suggest that there may be potential for reducing methanogen or CH4 production in Hanwoo steers by supplementing their feed with lauric acid and Acetogenic bacteria. However, the very small size of this study must also be considered (4 steers total). The authors suggest that dietary supplementation with LA and AP may inhibit CH4 production in Hanwoo cattle by changing rumen microbial populations and also by competing with methanogens for hydrogen and carbon dioxide, which the Acetogens use for making acetate. Overall, larger and more in-depth studies is warranted.

To view the article, “Effects of reductive acetogenic bacteria and lauric acid on in vivo ruminal fermentation, microbial populations, and methane mitigation in Hanwoo steers in South Korea,” visit the Journal of Animal Science.