Adapted methods to quantify, predict and mitigate enteric methane in sub-Saharan Africa

Abstract

Several methods have been proposed for in vivo measurement, prediction and mitigation of ruminant enteric methane (eCH₄) emissions. Most of these methods are expensive, technically complex and not adapted to the specificities of livestock systems in Sub-Saharan Africa (SSA). This review aims to analyze the different individual measurement techniques according to farming conditions in SSA. In vivo measurement techniques include the respiratory chamber, the ventilated hood, the GreenFeed system (C-Lock) and sulfur hexafluoride as a tracer. They are discussed and classified according to their field of application. The eCH₄'s indirect measurement approaches rely on proxies (or predictors) derived from different biological matrices. In SSA, the proxies likely to be used in the various rearing conditions are the characteristics of intake (quantity, composition), milk (quantity, global composition estimated by MIR spectra), faeces (archeols, global composition estimated by SPIR spectra) or exhaled gases. Furthermore, potential eCH₄ mitigation strategies adapted to SSA include 1) the use of tree legumes, by-product-based concentrates, crop co-products and residues, and preserved forages; 2) grazing improvement; 3) replacement of unproductive animals; 4) maintaining of animal good health; and 5) reducing of females first calving age.