Effect of rice bran extract on in vitro rumen fermentation and methane production.

This study was done to investigate which components of rice bran (RB) are involved in the inhibition of methanogenesis by fractionating the rice bran and adding it to a rumen in vitro culture system. The RB extract obtained using ethanol and water was screened in an in vitro fermentation system. The experimental treatment conditions were as follows: a control group containing a substrate without supplements; substrates with 0.06 g of RB; 0.6 mL of ethanol; 0.6 mL of distilled water (DW); 0.6 mL of ethanol-soluble fraction (ESF); 0.06 g of ethanol-insoluble rice bran (EIRB); 0.6 mL of water-soluble fraction (WSF); and 0.06 g of water-insoluble rice bran (WIRB). Based on the result of the analysis, the addition of ESF significantly decreased CH4 and CH4 /g dry matter digested, methanogen population (p < 0.05), while gas and dry matter digestibility (DMD) were comparable with the control group. Total short-chain fatty acid (SCFA), and proportion of propionate were reduced, and the proportion of butyrate was increased by the addition of ethanol and ESF (p < 0.05). This result suggests that the supplementation of 10% ESF can substantially reduce methane production in vitro without a negative effect on substrate digestibility.

Validation of a phenol-sulfuric acid method in a microplate format for the quantification of soluble sugars in ruminant feeds.

Soluble sugars in feeds are important for ruminant production; however, performing numerous sugar analyses within a short period is a laborious task. Here, we developed a phenol-sulfuric acid (PSA) assay in a microplate format to quantify soluble sugars in ruminant feeds. This method is easy and quick and requires only a small quantity of harmful reagents. We found that assay measurements were not affected by the representative organic acids and sugar alcohol contained in feeds. The treatment of activated charcoal with ethanol extract prior to the PSA assay was effective in removing interfering compounds for a more accurate determination of soluble sugars in certain feeds. Furthermore, the inter-day and intra-day repeatability of the present method was acceptable. Hence, we conclude that the method developed in this study is suitable for routine analysis of soluble sugars content in ruminant feeds.