In vitro ruminal degradability, fermentation metabolites and methanogenesis of different crop residues

Abstract

In vitro rumen fermentation study of different source of crop residues used for livestock feeding in semi-arid region was conducted to compare the effects on degradability, fermentation metabolites and methanogenesis. Cereal crop residues (CCR) included pearl millet, barley, sorghum and wheat; leguminous crop residues (LCR) were chick pea, groundnut, and clusterbean; oilseed crop residues (OCR) were sesamum, and mustard; and spices crop residues (SCR) was cumin and fennel. The samples were incubated with ruminal buffer in glass syringes under anaerobic conditions for assessing the ruminal fermentation attributes. The degradability and methanogenesis parameters were assessed at t1/2(h), being determined following fermentation kinetic study of the crop residues. The CP content (g/kg DM) in legumes crop residues (80.6-194) was higher (P<0.05) in legume and spices crop residues compared to oilseed and cereal crop residues. LCR produced highest and SCR lowest (P<0.05) cumulative gas at t1/2(h). Pearl millet, cumin and groundnut crop residues produced lowest whereas sesamum and mustard crop residues produced highest methane at t1/2(h). The OCR had lower DM digestibility and highest methane per unit digestible DM. Total volatile fatty acids production was higher in fermented substrate of clusterbean, groundnut, sorghum, and wheat having higher proportion of propionate. Above all, pearlmillet, cumin and groundnut crop residues produced less CH4 without compromising digestion and thus feeding of these crop residues could be a strategy to reduce CH4 emissions.