Methanogenic potential of forages consumed throughout the year by cattle in a Sahelian pastoral area

Abstract

Methane (CH4) emission from ruminants in African pastoral systems may be affected by intake and type of plants, which vary highly between rainy and dry seasons. In each of two sites located in the semiarid Sahelian area of Senegal, three Gobra zebus were monitored throughout 1 year. A representative sample of their diet was obtained once every month. Diet was mainly composed of grasses, herbaceous legumes, tree and shrub foliage and pods, and dried forage residues. CH4 production and volatile fatty acid (VFA) concentration, which reflects VFA production, were determined in vitro. Crude protein, neutral detergent fibre (NDF) and acid detergent fibre were measured by near-infrared spectrophotometry. CH4 production varied between 24.6 and 35.2 mL/g forage dry matter (DM), being minimal in August (rainy season) and maximal in February (dry season). Seasonal difference disappeared when CH4 was expressed in mL/g NDF. The acetate : propionate ratio varied in the same way as CH4 (3.2 and 4.6 in August and February, respectively); VFA concentration was minimum in March and maximum in September (69.2 and 77.4 mmol/L, respectively). CH4 production was closely related to dietary NDF content (r = 0.82) and to acetate : propionate ratio (r = 0.96). For six successive periods (February to July), plant categories constituting the diet were incubated separately. Reconstituting the CH4 production and VFA concentration in the diet on the basis of the proportion of plant components gave values similar to those of the global diet (33.4 and 34.2 mL CH4/g DM and 75.9 and 70.9 mmol VFA/L, respectively). This result suggests the absence of interaction among plant components on rumen fermentation. (Résumé d'auteur

Methanogenic potential of commonly utilised South African subtropical and temperate grass species as influenced by nitrogen fertilisation

“…gayana. These results correspond with results reported by Gemeda and Hassen (2014) and Doreau et al (2016) who reported a positive correlation between CH4 production, cell wall contents and IVOMD of forages. Digitaria eriantha had the lowest average in vitro CH4 production after the 24 and 48 hour incubation periods and tended to have a lower CH4: TGP compared to other C4 species (Table 6) in the present trial.…”

Chemical composition, ruminal degradation kinetics, and methane production (in vitro) of winter grass species

“…In vitro fermentation has been proven to be a successful method for the screening of forage fermentation characteristics and methanogenic potential 12,13 . The advanced, fully automated in vitro gas production (IVGP) technique has been widely used to measure the rate and extent of fermentation of a large number of feed samples 6 .…”

Analysis of Inputs Parameters Used to Estimate Enteric Methane Emission Factors Applying a Tier 2 Model: Case Study of Native Cattle in Senegal

“…Considering the absence of reliable information on livestock in the SSA region, the IPCC Guidelines suggest that the uncertainty of enteric fermentation emission factors ranges from ±30% to ±50% for Tier 1 and ± 20% for Tier 2 approaches, respectively [5]. Hence, the use of a Tier 2 approach may enable a decrease in the uncertainty of predicted enteric methane emission factors used in national GHG inventories [53][54][55]. In Senegal, the third GHG emission inventory was submitted to the UNFCCC in 2015 (see https://unfccc.int/documents/89618).…”

“…The composition of fodder consumed by ruminants is well documented in Senegal, and the profile of organic matter digestibility (OMd) is available [13][14][15]54]. However, there is a need to determine at the national scale, an average value for OMd which takes into consideration seasonality.…”