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

Abstract

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).

Understanding intestinal health in nursery pigs and the relevant nutritional strategies

“…The major target of these alternatives has been affecting and improving intestinal health of pigs with some promising outcomes but still without complete answers to replace AGP [ 9 , 54 , 55 ]. Potential and partial success has been obtained from the use of prebiotics [ 56 , 57 ], probiotics or direct-fed microbials [ 53 , 58 ], postbiotics [ 59 – 61 ], phytobiotics [ 62 – 64 ], non-starch polysaccharide degrading enzymes (NSPases) [ 24 , 65 – 67 ], functional amino acids [ 68 – 70 ], acidifiers or organic acids [ 71 , 72 ], and other bioactive compounds [ 38 , 73 , 74 ].…”

Using Nutritional Strategies to Shape the Gastro-Intestinal Tracts of Suckling and Weaned Piglets

“…Organic acids that can be added to the feed or water can act through (1) their direct bacteriostatic/bactericidal effects and by (2) decreasing stomach pH, thereby improving the onset of protein digestion and reducing the survival of pathogens [ 156 ]. Organic acids may also have other modes of action (e.g., as an energy source) along other segments of the digestive tract, as described in previous reviews [ 157 , 158 ]. It should be noted that organic acids can differ in their anti-bacterial properties and their capacity to reduce stomach pH, in which factors including molecular weight, p K a , chain length and buffer capacity play an important role [ 159 ].…”

“…It should be noted that organic acids can differ in their anti-bacterial properties and their capacity to reduce stomach pH, in which factors including molecular weight, p K a , chain length and buffer capacity play an important role [ 159 ]. Furthermore, the use of a blend of organic acids is preferable to the use of a single acid, as together they have a wider range of anti-bacterial properties [ 158 ]. For example, one organic acid may result in the fast reduction in the stomach pH, whilst another may undissociate more quickly at that pH and enter the pathogenic cell wall [ 160 ].…”

Timely Control of Gastrointestinal Eubiosis: A Strategic Pillar of Pig Health

“…Organic acids have been widely used for decades in pig feed as a preserver of feed nutritional qualities [133]. Previous reviews have analyzed the effect of several single and mixed organic acids on post-weaning microbial composition [134,135]. The effects of organic acids in the modulation of intestinal microbiota in post-weaning piglets have been mainly ascribed to their capacity to reduce the pH of the stomach.…”

“…It is known that diet is one of the main factors affecting the microbial profile, there are several reviews dealing with feeding strategies, especially regarding feed additives as gut microbial modulators [117,134,135,141]. However, to avoid redundancy with other reviews specifically focused on nutrients, feed additives and feeding strategies as gut microbial modulators, the authors present an overview of the most promising feeding interventions which modulate the gut microbiota.…”