Interpretive Summary: Apparent jejunal amino acid digestibility, gut morphology, and the expression of intestinal amino acid transporters in pigs fed protein or free amino acids

By: Francis Amann Eugenio, Jaap van Milgen, Joël Duperray, Renaud Sergheraert, Nathalie Le Floc’h

The amino acids (AA) in the diet of pigs are usually supplied as a mix of proteins and free AA. Proteins need to be digested first before their constituent AA become available to the animal. Free AA, together with small peptides, are readily available without the need for digestion. Moreover, the different forms by which AA are supplied may also have an effect on intestinal physiology. In this experiment, pigs were fed different diets with the same AA profile but were provided either as protein, as free AA and small peptides originating from hydrolyzed protein, or as a mix of individual free AA. Results showed that feeding pigs free AA and/or small peptides resulted in higher apparent jejunal digestibility of AA compared to feeding proteins. Furthermore, the apparent jejunal digestibility of the AA of a hydrolyzed protein was higher than that of free AA. Providing diets with readily absorbable AA resulted in a higher surface area for absorption and an increase in the gene expression of AA transporters as opposed to proteins.