What is the main mode of action of organic acids as feed additives?

• A. They raise gut pH to preserve feed.
• B. They have no preservative effect.
• C. They lower gut pH to preserve feed and inhibit pathogens.
• D. They act only as energy sources.

Answer: (C)

Organic acids mainly work by lowering the pH in the gut and in the feed, creating an acidic environment that slows the growth of spoilage microorganisms and inhibits pathogens. The acidic form that remains undissociated can penetrate microbial cell membranes and then dissociate inside the cell, acidifying the cytoplasm and disrupting enzymes and metabolic processes. This antimicrobial action helps preserve feed and promotes a healthier gut environment for the animal. While some organic acids can serve as energy sources after metabolism, that is not their primary action as feed additives, and they do not raise gut pH.