Potential emissions of enteric methane by ruminants: comparison between animal species and mitigation strategies

Abstract

The aim of this study is to evaluate the potential for methanogenesis of dairy cattle (Bos taurus taurus), beef cattle (Bos taurus indicus), buffalo (Bubalus bubalis), sheep (Ovis aries) and goats (Capra hircus) fed similar diets. Moreover, it is intended to: i. assess, using the in vitro gas production technique, the rumen fermentation efficiency of the different ruminant species; ii. check for differences between ruminant species regarding the methanogenesis during fermentation of forages; iii. study if the reactivity of the same tannin source is the same for the different ruminant species; and iv. estimate the ability of enteric methane mitigation through the addition of tannins in the diet. The experiment will be carried out at the FZEA, in collaboration with the CENA, both USP institutions. Fifteen animals will b used, three of each species, as inoculum donors (rumen content). By the in vitro gas production technique, following roughages will be evaluated: corn silage, elephant grass silage, Tifton 85 hay, alfalfa hay and Brachiaria decumbens grass. The extract of acacia will be used as an external source of tannins. Concomitantly to the conventional gas production assay, emissions of methane and concentrations of short chain fatty acids will be determined. The experiment will include, therefore, five sources of inoculum (animals) to test five feeds (substrates) each with two treatments (with and without tannins). These parameters will be adjusted in a randomized design. The results will be compared by Tukey test with a probability level of 5%. (AU)