Amino Acid Release Patterns From Different Protein Diet Sources And Its Effect On Amino Acid Absorption In The Portal Vein Of Growing Pigs

The source of protein in animal diet can affect the release dynamics of amino acids in the animal's intestine and it's absorption in the portal vein.In this study,corn-soybean meal diet was used as the control group,while soybean meal,corn gluten meal,fish meal,and fermented soybean meal were used as different protein sources to formulate a growing pig diet.The standard ileal digestibility(SID)of amino acids was supplemented with crystalline amino acids to achieve a balanced diet.To simulate the pig gastrointestinal environment,the four dietary groups were subjected to in vitro digestion.The concentration of free amino acids in digestive juices after in vitro digestion was measured by ultra-high performance liquid chromatography(HPLC),and the amino acid release patterns of diets from the various protein sources were analyzed.The dynamic changes of amino acid absorption in the portal vein of growing pigs were determined by portal vein cannulation.The results of in vitro amino acid release patterns indicate that the contents of total free amino acids in the diets of the four groups were significantly different due to the addition of different amounts of synthetic amino acids which were expressed as soybean meal> corn gluten meal group> fish meal group> fermented soybean meal group(P < 0.05).However,the total free amino acid content in the fermented soybean meal group was significantly higher than the other three groups due to the difference in the release rate of amino acids between protein sources during the 4h in vitro digestion process.There was no significant difference in total free amino acid content between the soybean meal group,the fish meal group and the corn gluten meal group during the 8 to 16 h in vitro digestion period.However,the fermented soybean meal group still maintained a high level of total free amino acids(P < 0.05).The release rates of the other three groups were different resulting in the total free amino acid levels of the order,soybean meal group > fish meal group.The results of dynamic changes in free amino acid levels in portal vein serum indicate that dietary amino acid release patterns can significantly affect the absorption of amino acids in growing pigs,and the dynamic changes in amino acid levels in portal veins of growing pigs after feeding on four groups of diets Significant.The effect of synthetic amino acids on the absorption of intestinal amino acids was eliminated.After feeding the fermented soybean meal diet,the amino acid absorption in the portal vein reached the shortest peak,and reached the peak of amino acid absorption at about 2 h after ingestion.The soybean meal group and the fish meal group took the second place.At about 3h,corn gluten meal appeared around 4h.The amino acid balance absorbed by the portal vein of the fermented soybean meal group was the best,followed by the soybean meal group and the fish meal group,and the corn protein meal group was the worst.