ARS | Publication request: Microbial production of volatile sulphur compounds in the large intestine of pigs fed two different diets

Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 10, 2012
Publication Date: May 31, 2012
Citation: Poulsen, H.V., Jensen, B.B., Finster, K., Spence, C., Whitehead, T.R., Cotta, M.A., Canibe, N. 2012. Microbial production of volatile sulphur compounds in the large intestine of pigs fed two different diets. Journal of Applied Microbiology. 113:143-154.

Interpretive Summary: Diet components in swine feed are important for proper growth and health of the animals. However, little is known regarding microbial production of volatile sulfur compounds in the gastrointestinal tract and the impact of adding dried distillers' grain and solubles (DGGS), which are produced by the ethanol industry, to the diet. Such compounds may be detrimental to the gastrointestinal (GI) tract and reduce animal growth and performance. We now present results of feeding control diet and one with DGGS on the production of sulfur compounds in the GI tract of swine. The results indicate that sulfur compounds are produced throughout the large intestines, and the bacteria that produce and use the compounds can be affected by the dietary composition. This information will be useful in determining dietary guidelines for the swine industry.

Technical Abstract: Only little is known about the microbial production of volatile sulphur compounds (VSC) in the 18 gastrointestinal tract, the dietary influence, and the magnitude of this production. To investigate intestinal VSC production in more detail, pigs were fed diets based on either wheat and barley (CONTROL) or wheat and dried distillers’ grains with solubles (DDGS). Net production of VSC was followed in intestinal content from four segments of the large intestine. In addition, the potential sulphate reduction rate (SRR) was determined and the number of sulphate reducing bacteria (SRB) and the total bacteria number were determined by quantitative polymerase chain reaction (PCR). Hydrogen sulphide, methanethiol, and dimethyl sulphide were found in digesta from all four segments, though their distribution and magnitude of production differed widely. The net production rate of hydrogen sulphide increased from cecum towards the distal colon and was significantly higher in the pigs fed the CONTROL diet. Also, the potential SRR (sulphate saturated) was significantly higher in the CONTROL pigs, whereas no diet-related difference was observed in numbers of SRB or total number of bacteria. The net methanethiol production rate was significantly higher in the pigs fed the DDGS diet, while no difference was observed for dimethyl sulphide net production rates. Overall, the results showed that VSC are produced throughout the large intestine of pigs. The observed effects of diet strongly suggest that the microbial processes involved in VSC production and consumption can be affected by dietary composition and that inclusion of DDGS in pig diets might adversely affect odour emission.