Greenhouse gas emissions and mitigation in the West African sub-region: challenges and opportunities

Abstract Text: Animal agriculture contributes to  about  18%  of the global GHG of which 3% is generated  by  all  ruminants  in  sub-Saharan  Africa. The methane emissions from these ruminants represent about 12% of the gross energy intake which could otherwise be used as energy for maintenance. In an attempt therefore to reduce emissions, researchers in the West African sub region have initiated profiling GHG emissions of feed resources and selection feed with less methane emission potential. Some common feedstuffs in the sub-region were assayed for their methane production using either the in vitro systems or hand-held methane analyser. In vitro assessment of shea nut (Butyrospermum parkii) for methane production  indicated that including 10% of shea-nut cake in finishing feedlot Bos taurus  diets reduced 24 h in vitro methane production by approximately 20% without any significant reduction in total and individual volatile fatty acid production. Methane output was also reduced during in vitro ruminal fermentation of Brachiaria ruziziensis when the in vitro mixture was supplemented with 20% of leaves of the browse plant Securinega virosa. Different fractions of Napier grass were evaluated in Ghana for methane production using a hand-held methane analyser. The stem fraction was 2.5 times higher than that of the leaves and as the grass advanced in age, the methane production increased. Emissions directly associated with animal production have increased globally partly because of the high demand for animal products. It is envisaged that emission intensity from animal agriculture in the West African sub-region will increase due to the nature of feed they feed on. In an attempt to reduce emissions from animals, scientists adopt in vitro method of screening and selection of feed for ruminants. This however fails to estimate emission per feed intake making it impossible to advance the best practices that result in GHG mitigation without any adverse effect on animal productivity. Though the Global research alliance suggests to its member countries of which Ghana is one, to focus on activities that reduce emissions intensity of livestock while increasing productivity, little is seen in terms of investment in developing research activities that reduces emissions. Several agro-by products including palm kennel cake and other cakes of leguminous crop exist in the sub-region. Owing to their high lipids content, when supplemented to the high fibrous diet consumed by ruminants, it is certain that not only will methane emissions reduce, but productivity will also increase. 

Keywords: methane, mitigation, Africa