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The effect of betaine on in vitro fermentation of carbohydrate and protein combinations under osmotic stress in pigs.

BACKGROUND
There is evidence that dietary betaine might improve nutrient digestibilities in pigs due to its osmoprotective properties. This in vitro study was performed to assess the potential of supplemented betaine sources to affect fermentation characteristics of different carbohydrate and protein combinations, under conditions of osmotic stress. In vitro fermentation was performed by use of the modified Hohenheim gas test with pig faeces as microbial inoculum.


RESULTS
At the end of in vitro fermentation under osmotic stress conditions, differences (P < 0.05) in gas production, ammonia concentration, and concentration of short-chain fatty acids were observed for the different carbohydrates, while for the two proteins only differences (P < 0.05) in ammonia and short-chain fatty acid concentration were obtained. Supplementation of a native betaine source rather than addition of pure betaine increased propionic acid (P < 0.05) and butyric acid (P < 0.05) production.


CONCLUSION
These results suggest that only supplementation of a native betaine source but not of pure betaine products affects microbial fermentation under osmotic stress. Furthermore, both the carbohydrate and protein source play an important role in modifying microbial activity under osmotic stress conditions. It can also be concluded that the modified Hohenheim gas test is suitable to scrutinise fermentation activity of different assay substrates under osmotic stress.