Effects of the addition of some medicinal plants on methane production in a rumen simulating fermenter (RUSITEC)

Plant material from Rheum palmatum (root) and Frangula alnus (bark) were tested to study their effects as feed additives to decrease methane production from ruminal fermentation of a forage-based diet, using a rumen simulating fermenter (RUSITEC). Sixteen fermentation units (vessels) were set up for the experiment that lasted 19 days. Each vessel was fed 16 g of a mixed substrate consisting of 800 g/kg forage and 200 g/kg concentrate. Treatments were assigned to the experimental units (vessels) according to a completely random design. Treatment vessels were supplied with either milled root from R. palmatum or milled bark from F. alnus (four vessels per plant species) added at 1 g/day (62.5 mg additive/g substrate or 1.66 g/l in the fermenter). Another four vessels received 12 μM of monensin (positive control) added to the basal diet, and the remaining four vessels were controls (no additive). Monensin induced changes that were coincident with those usually reported in the literature. R. palmatum caused a significant decrease in methane production, associated with changes in the VFA production pattern. F. alnus altered slightly fermentation parameters.