Profiles Of Amino Acids Released From Different Nitrogen Composited Diets In Different Segments Of The Gastrointestinal Tract Of Pigs

This study was conducted to determine the profiles of AA in different segments of the gastrointestinal tract of pigs fed with different nitrogen composited diets. Twenty-four pigs (19.5 kg BW) were randomly assigned into 4 groups (6 pigs per group) and fed diets containing corn and fish meal (FM), soybean meal (SBM), cottonseed meal (CM), or rapeseed meal (RM) with equivalent AA compositions for 7 d. The contents of the stomach, proximal jejunum, distal jejunum, and ileum were collected at 4 h after feeding. The hydrolysate AA of undigested protein, free AA (FAA), and peptide-bound AA (PAA) in the contents were determined. There were more FAA in the proximal jejunum of SBM protein diets treatment, whereas more peptides were obtained from FM protein diets in the stomach and ileum as well as from SBM protein diets in the distal jejunum. The concentrations of FAA in the proximal jejunum and ileum as well as PAA in the jejunum with RM were higher than those with CM. When all 4 treatments were considered together, whereas few FAA were in the stomach and then increased in the jejunum and ileum, PAA were distributed uniformly in the 4 segments. These results showed that the RM protein diet gave a relatively continuous release of hydrolysis products in the stomach and small intestine. And FM and SBM protein diets were superior to CM for the release of peptides and FAA in the proximal gastrointestinal tract. These results regarding the AA profiles in different segments of the gastrointestinal tract should help to provide some information for the application of CM and RM in pigs.