Characteristics of Amino Acid and Glucose Digestion and Metabolism in Energy and Protein Feedstuffs for Pigs

The objective of this study is to investigate the digestion and metabolism characteristics of amino acids and glucose in energy and protein feeds, and to establish regression equations to accurately predict their release rates in vivo based on the in vitro digestion characteristics of the feedstuffs. A total of 9 energy feedstuffs and 19 protein feedstuffs were selected for in vitro digestion simulation experiments. Additionally, four representative energy and protein feeds were then chosen for the portal vein, femoral artery, and femoral vein blood cannulation experiments in growing pigs. The results showed that among the nine energy feedstuffs tested, wheat bran presented the highest degree of digestion, followed by wheat, whereas potato had the lowest degree of digestion. The digestibility of starch at different time points in vitro was linearly correlated with the crude fiber content, total starch content, and ratio of amylose to amylopectin (R² = 0.61~0.96). Among the 19 protein feedstuffs tested, peas released the highest total amount of amino acids, followed by sugar beet meal. The in vivo digestibility and metabolism trial in cannulated pigs showed that the total amino acid release was linearly correlated with the in vitro amino acid release rates, dry matter, crude protein, neutral detergent fiber, crude fat, and total energy of the feedstuffs (R² = 0.93~0.99).