B. Metzler and R. Mosenthin 49ConclusionsLiterature available to date reveal that organic acids represent a useful alternative to in-feed antibiotics in order to enhance and secure growth performance, and reduce pathogen loading in weaning and fattening pigs. This effect is more pronounced in the younger animal. Despite increasing information about the possible modes of action of organic acids in the different sections of the GIT, several aspects still require elucidation. The extent to which organic acids affect growth performance and digestibility depends on the type and the inclusion level of the acid used, as well as on diet and animal factors. Although research results vary, organic acids may enhance the digestibilities of protein and amino acids in weaned and fattening pigs. Regarding their antimicrobial activity, organic acids selectively inhibit the proliferation of harmful bacteria in the proximal part of the digestive tract (stomach and small intestine).referencesAumatre, A., Peiniau, J. and Madec, F. (1995) Digestive adaptation after weaning and nutritional consequences in the piglet. Pig News and Information 16: 73N-79N. Best, P. (2000) Adding acids to swine diets. Feed management 51: 19-22. Blank, R., Mosenthin, R., Sauer, W.C. and Huang, S. (1999) Effect of fumaric acid and dietary buffering capacity on ileal and fecal amino acid digestibilities in early-weaned pigs. Journal of Animal Science 77: 2974-2984. Blank, R., Sauer, W.C., Mosenthin, R., Zentek, J., Huang, S. and Roth, S. (2001) Effect of fumaric acid supplementation and dietary buffering capacity on the concentration of microbial metabolites in ileal digesta of young pigs. Canadian Journal of Animal Science 81: 345-353. Boling, S.D., Webel, D.M., Mavromichalis, I., Parsons, C.M. and Baker, D.H. (2000) The effect of citric acid on phytate-phosphorus utilization in young chicks and pigs. Journal of Animal Sciences 78: 682-689. Canibe, N., Steien, S.H., verland, M. and Jensen, B.B. (2001) Effect of K-diformate in starter diets on acidity, microbiota, and the amount of organic acids in the digestive tract of piglets, and on gastric alterations. Journal of Animal Science 79: 2123-2133. Canibe, N., Hjberg, O., Hjsgaard, S. and Jensen, B.B. (2005) Feed physical form and formic acid addition to the feed affect the gastrointestinal ecology and growth performance of growing pigs. Journal of Animal Science 83: 1287-1302. Cranwell, P.D. and Titchen, D.A. (1974) Gastric secretion in newly born pigs. Research in Veterinary Science 16: 105-107.
