Abstract: 【Objective】 This study aimed to investigate the effects of dietary fiber levels and digesta collection periods on ileal digesta digestive enzyme activities,nutrient flow,and short-chain fatty acid (SCFA) composition and content in growing pigs. 【Method】 A single-factor completely randomized design was employed,with 18 pigs fitted with T-cannulas at the terminal ileum randomly assigned to three treatments (6 pigs per treatment).The treatments included a control diet,a 10% alfalfa fiber diet,and a 20% alfalfa fiber diet.Ileal digesta samples were collected over two 10-day periods to determine activities of amylase,lipase,trypsin,and chymotrypsin,analyze nutrient flow,and measure SCFA content. 【Result】 ①The ileal digesta pH in growing pigs increased significantly with elevated dietary fiber levels,and the differences between groups were extremely significant (P＜0.01).The activities of amylase,trypsin,and chymotrypsin in the ileal digesta of growing pigs in high fiber group were significantly lower than those in other dietary groups (P＜0.05).Collection periods had no significant effects on ileal pH or the four digestive enzymes (P＞0.05).②Compared with the control group,the total carbohydrate and acid detergent fiber flow in the ileum of growing pigs in both experimental groups increased significantly (P＜0.01),while the crude fat flow decreased significantly (P＜0.01).Collection periods did not affect nutrient or energy flow in the ileum (P＞0.05).③The contents of acetic acid,valeric acid,and total SCFAs in the ileal digesta of growing pigs in the high fiber group were significantly higher than those in the other treatment groups (P＜0.05).As the collection period of the experiment extended,the concentrations of propionic acid,valeric acid,and total SCFAs in ileal digesta significantly increased (P＜0.01). 【Conclusion】 High-fiber diets reduced ileal digestive enzyme activities but increased ileal flows of carbohydrates,fiber,and total SCFAs in growing pigs.Collection periods did not influence digestive enzyme activities or nutrient flow,but extended fiber intake duration enhanced ileal fermentation capacity.

Key words: dietary fiber; digestive enzyme; nutrient flow; short chain fatty acid; pig