Methanogenic potential of forages consumed throughout the year by cattle in a Sahelian pastoral area
2016
Doreau, Michel | Benhissi, Hanen | Thior, Yakhya Elhadji | Bois, Bérénice | Leydet, Claire | Genestoux, Lucette | Lecomte, Philippe | Morgavi, Diego | Ickowicz, Alexandre | Unité Mixte de Recherche sur les Herbivores - UMR 1213 (UMRH) ; Institut National de la Recherche Agronomique (INRA)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS) | Laboratoire National d'Elevage et de Recherches Vétérinaires [Dakar] (LNERV) ; Institut sénégalais de recherches agricoles [Dakar] (ISRA) | Systèmes d'élevage méditerranéens et tropicaux (UMR SELMET) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro) | UE | European Project: 266018,EC:FP7:KBBE,FP7-KBBE-2010-4,ANIMALCHANGE(2011)
Methane (CH4) emission from ruminants in African pastoral systems may be affected by intake and type ofplants, 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. CH4production and volatile fatty acid (VFA) concentration, which reflects VFA production, were determined in vitro. Crudeprotein, neutral detergent fibre (NDF) and acid detergent fibre were measured by near-infrared spectrophotometry. CH4production varied between 24.6 and 35.2 mL/g forage dry matter (DM), being minimal in August (rainy season) and maximalin February (dry season). Seasonal difference disappeared when CH4 was expressed in mL/g NDF. The acetate : propionateratio varied in the same way asCH4 (3.2 and 4.6 in August and February, respectively); VFA concentration was minimum inMarch andmaximumin September (69.2 and 77.4 mmol/L, respectively).CH4 production was closely related to dietaryNDFcontent (r = 0.82) and to acetate : propionate ratio (r = 0.96). For six successive periods (February to July), plant categoriesconstituting the diet were incubated separately. Reconstituting the CH4 production and VFA concentration in the diet on thebasis of the proportion of plant components gave values similar to those of the global diet (33.4 and 34.2 mL CH4/g DMand 75.9 and 70.9 mmol VFA/L, respectively). This result suggests the absence of interaction among plant components onrumen fermentation.
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