Dietary Supplementation of Inorganic, Organic, and Fatty Acids in Pig: A Review.

Reduction of antibiotic use has been a hot topic of research over the past decades. The European ban on growth-promoter use has increased the use of feed additivities that can enhance animal growth performance and health status, particularly during critical and stressful phases of life. Pig farming is characterized by several stressful periods, such as the weaning phase, and studies have suggested that the proper use of feed additives during stress could prevent disease and enhance performance through modulation of the gastrointestinal tract mucosa and microbiome. The types of feed additive include acids, minerals, prebiotics, probiotics, yeast, nucleotides, and phytoproducts. This review focuses on commonly used acids, classified as inorganic, organic, and fatty acids, and their beneficial and potential effects, which are widely reported in the bibliography. Acids have long been used as feed acidifiers and preservatives, and were more recently introduced into feed formulated for young pigs with the goal of stabilizing the stomach pH to offset their reduced digestive capacity. In addition, some organic acids represent intermediary products of the tricarboxylic acid cycle (TCA), and thus could be considered an energy source. Moreover, antimicrobial properties have been exploited to modulate microbiota populations and reduce pathogenic bacteria. Given these potential benefits, organic acids are no longer seen as simple acidifiers, but rather as growth promoters and potential antibiotic substitutes owing to their beneficial action on the gastrointestinal tract (GIT).