Nutritive and Antimicrobial Effects of Organic Acids in Pigs

The mode of action of organic acids is two fold referring to the fact that they consist of a proton and anion. The proton effect of an organic acid is based on the acidification of feed and digesta and the anion effect on its ability to inhibit growth of microbes. The extent of the anti-microbial properties of organic acids depends on their ability to change from the undissociated to the dissociated form. The latter is mainly influenced by the environmental pH relative to their pKa value. The pKa value indicates at which pH 50% of the acid is dissociated. In their undissociated form organic acids passively diffuse through the bacterial wall and interfere with the fine-tuned pH balance in the cytoplasm, which upsets the energy balance and disrupts biochemical processes. Suppression of cellular enzymes transport systems is also reported, which prevents bacteria from multiplying.