Organic acids for performance enhancement in pig diets

Organic acids and their salts appear to be potential alternatives to prophy lactic in-feed antibiotics and growth promoters in order to improve the per formance of weaned piglets, fattening pigs and reproductive sows, although their growth-promoting effects are generally less than that of antibiotics. Based on an analysis of published data, the growth-promoting effect of for mates, fumarates and citrates did not differ in weaned piglets. In fattenin g pigs, formates were the most effective followed by fumarates, whereas pro pionates did not improve growth performance These acids improved the feed:g ain ratio of both weaned piglets and fattening pigs. In weaned piglets, the growth-promoting effects of dietary organic acids appear to depend greatly on their influence on feed intake. In sows, organic acids may have anti-ag alactia properties. Successful application of organic acids in the diets fo r pigs requires an understanding of their modes of action. It is generally considered that dietary organic acids or their salts lower gastric pH, resu lting in increased activity of proteolytic enzymes and gastric retention ti me, and thus improved protein digestion. Reduced gastric pH and increased r etention time have been difficult to demonstrate, whereas improved apparent ileal digestibilities of protein and amino acids have been observed with g rowing pigs, but not in weaned piglets. Organic acids may influence mucosal morphology, as well as stimulate pancreatic secretions, and they also serv e as substrates in intermediary metabolism. These may further contribute to improved digestion, absorption and retention of many dietary nutrients. Or ganic acid supple mentation reduces dietary buffering capacity, which is ex pected to slow down the proliferation and/or colonization of undesirable mi crobes, e.g. Escherichia coli, in the gastro-ileal region. However, reduced scouring has been observed in only a few studies. As performance responses to dietary organic acids in pigs often varies, more specific studies are n ecessary to elucidate an explanation.