ENDOGENOUS AMINO-ACID FLOW IN THE STOMACH AND SMALL-INTESTINE OF THE YOUNG GROWING PIG

Endogenous ileal amino acid flows were determined in the young growing pig given an enzymically hydrolysed casein (EHC)-based diet with subsequent treatment of the digesta by ultrafiltration. Comparison was made with endogenous excretions obtained from pigs fed an EHC-based or a protein-free diet but without treatment of the digesta. Ten entire male pigs of 15 kg liveweight were fed either an EHC-based diet or a protein-free diet, and samples of digesta were collected following euthanasia. The digesta from the EHC-fed pigs were divided into two equal portions. One portion was untreated, and the second portion was ultrafiltered after centrifugation with the retentate (high-molecular-weight fraction) being added to the precipitate. Endogenous ileal amino acid flows were determined for the untreated digesta and for the digesta following the centrifugation plus ultrafiltration treatment. Except for arginine, glycine, leucine and phenylalanine, the endogenous amino acid flows were significantly (P < 0.05) higher for the untreated digesta than for the digesta following the centrifugation plus ultrafiltration treatment. The pigs fed a protein-free diet generally had lower amino acid flows than those fed the EHC-based diet (ultrafiltration treatment), significantly (P < 0.05) so for lysine, aspartic acid, threonine, serine, glutamic acid, glycine, valine, isoleucine and leucine. The endogenous flows in different segments of the upper digestive tract of the young growing pig were also determined in the animals fed the protein-free diet. The endogenous amino acid flow was highest in the second third of the upper digestive tract. There was a significant (P < 0.05) difference between the amino acid flows determined in the first and second thirds of the small intestine for most of the amino acids.