Dose–Response Effects of Bamboo Leaves on Rumen Methane Production, Fermentation Characteristics, and Microbial Abundance In Vitro

SIMPLE SUMMARY: Due to economic, environmental, and nutritional considerations, mitigating enteric methane production from ruminants is an important issue. Nutritionists have recently shown that feeding livestock natural feed additives could ameliorate this problem, due to the antimicrobial activities of the biologically active components in the additives. Bamboo is widely distributed in Asia and is currently being used in construction and paper pulp production, which results in a significant amount of bamboo leaves as by-products. The present study investigated whether bamboo leaves feeding can decrease methane production in ruminants. Here we found that bamboo leaves supplementation in vitro caused a 12.7–34.2% reduction in methane production after 12 and 48 h. Further studies are needed to demonstrate the effect of bamboo leaves supplementation in vivo, to determine its potential for mitigating methane production from ruminants. ABSTRACT: Ruminants produce large amounts of methane as part of their normal digestive processes. Recently, feed additives were shown to inhibit the microorganisms that produce methane in the rumen, consequently reducing methane emissions. The objective of this study was to evaluate the dose–response effect of Phyllostachys nigra var. henonis (PHN) and Sasa borealis supplementation on in vitro rumen fermentation, methane, and carbon dioxide production, and the microbial population. An in vitro batch culture system was used, incubated without bamboo leaves (control) or with bamboo leaves (0.3, 0.6, and 0.9 g/L). After 48 h, total gas, methane, and carbon dioxide production decreased linearly with an increasing dose of bamboo leaves supplementation. The total volatile fatty acid, acetate, and acetate-to-propionate ratio were affected quadratically with increasing doses of bamboo leaves supplementation. In addition, propionate decreased linearly. Butyrate was increased linearly with increasing doses of PHN supplementation. The absolute values of total bacteria and methanogenic archaea decreased linearly and quadratically with an increasing dose of PHN treatment after 48 h. These results show that bamboo leaves supplementation can reduce methane production by directly affecting methanogenic archaea, depressing the metabolism of methanogenic microbes, or transforming the composition of the methanogenic community. These results need to be validated using in vivo feeding trials before implementation.