Abstract:In the present study, the gastric evacuation rates, hepatic and intestinal digestive enzyme activities, and serum glucose and cortisol concentrations in “Yunlong” groupers (Epinephelus moara ♀ × E. lanceolatus ♂: body weight (680.35±39.84) g) were evaluated to illustrate the characteristics of gastric evacuation and digestive enzyme activity. In addition, the degree of fitting of the gastric emptying curve was analyzed using a linear model, square root model, and cubic root model. The gastric evacuation rates of “Yunlong” groupers exhibited a typical curve digestive pattern (slow-fast-slow) during the gastric evacuation process. All the three mathematical models could fit the gastric evacuation data of “Yunlong” groupers; however, the cubic model obtained the optimal result. According to the cubic model, 80% (appetite basic recovery) and 100% (complete recovery of appetite) gastric emptying occurred at feeding after 9.5 hours and 14.8 hours in “Yunlong” groupers, respectively. The hepatic and intestinal digestive enzyme (amylase, chymotrypsin, and lipase) activities increased significantly from 0 to 6 h, and then decreased from 9 to 24 h during the gastric evacuation process in “Yunlong” groupers. The concentrations of serum glucose and cortisol corresponded with digestive enzyme activities during gastric emptying in “Yunlong” groupers. In addition, serum cortisol and glucose concentrations and digestive enzyme activity increased slowly from 0 h to 3 h, then increased significantly from 3 h to 6 h (P<0.05), with the highest values obtained at 6 h, and then decreased significantly until gastric evacuation was completed (P<0.05). In addition, the gastric evacuation rate was positively correlated with digestive enzyme activity during gastric evacuation in “Yunlong” groupers. In conclusion, the results reveal that the optimal interval feeding recommended is at 10 h and twice per day, based on the gastric evacuation rate and feeding digestion characteristics of “Yunlong” groupers in captivity.
