BioProject

The aim of this study was to investigate the effects of 3-nitrooxypropanol (3-NOP) and chloroform on methane and hydrogen production, rumen metabolites and microbial community structure in cattle fed a tropical roughage diet. More...

The aim of this study was to investigate the effects of 3-nitrooxypropanol (3-NOP) and chloroform on methane and hydrogen production, rumen metabolites and microbial community structure in cattle fed a tropical roughage diet. Eight rumen-fistulated steers were fed a roughage hay diet (Rhode grass; Chloris gayana). Four animals received the antimethanogenic compound chloroform (1.6 g choloroform-cyclodextrin /100 kg LW) while the other four received 3-NOP (2.5 g 3-NOP/ animal/ day) for 21 days. Methane reduction compared with control period was similar for both treatments (30 to 38 %) with no differences of H2 expelled between controls and treatments. Daily weight gain was significantly increased when animals were treated with 3-NOP compared with chloroform and control. Regarding the rumen fermentation parameters increases in ammonia, acetate and branched chain fatty acids were observed with both compounds compared with the controls. Also, methylamines, alcohols and dimethylsulfone concentrations were significantly increased with the treatments compared with control. The rumen microbiome analyses revealed a similar profile for both treatments, with a shift in operational taxonomic units (OTUs) assigned to the Prevotellaceae and Campylobacteraceae family. Moreover, major archaeal OTUs associated with Methanobrevibacter and Methanosphaera were significantly affected to varying extents based on the inhibitory treatments compared to the control. Also the abundance of the Methanobrevibacter spp was decreased by 3-NOP and chloroform, while the Methanomassiliicoccaceae family was inhibited only by 3-NOP. The results suggest that despite the specific mode of action of 3-NOP on methanogens, inhibition of methanogenesis by both compounds resulted in similar responses in metabolism and microbial community structure in the rumen. We hypothesized that these changes were driven by the redirection of metabolic hydrogen by both treatments. Therefore results from previous publications using chloroform as an inhibitor of methanogenesis may be useful in predicting rumen microbiome and fermentation responses to 3-NOP. Less...