Effect of rate of enteral nutrient supply on gut mass

Early enteral feeding after injury is important for maintenance of gut integrity. However, enteral nutrients are frequently administered at low rates because of decreased gastrointestinal motility. These low rates are said to 'maintain the gut.' This study was performed to evaluate the effect of rate of enteral nutrient delivery on gut mass. Six male Sprague-Dawley rats had no surgery and served as controls (ad libitum rat chow diet). Twenty-four male Sprague-Dawley rats underwent abdominal surgery for placement of gastroduodenal feeding tubes (tip located 2 cm into intestine from pylorus) and were randomized (n = 6 per group) to ad libitum rat chow, 1/2 strength peptide diet (Reabilan HN, RHN) at 1 mL/h (1/2RHN-1 mL), full- strength peptide diet at 2 mL/h (RHN-2 mL), or full-strength peptide diet at 4 mL/h (RHN-4 mL). These diets supplied approximately 30%, 13%, 50%, and 100% of rat recommended daily allowances. The control animals gained weight (38 ± 3 g over 5 days) whereas all postsurgery animals lost weight. Weight loss was greatest in the 1/2 RHN-1 mL (-55 ± 3 g over 5 days) and RHN-2 mL (-52 ± 6 g over 5 days) groups compared with the RHN-4 mL animals (-41 ± 5 g over 5 days). All animals fed liquid enteral diets had reduced gut weights compared with chow-fed animals. Gut weights did not differ between control and postsurgery ad libitum chow animals. Proximal gut mucosal protein content was significantly (p < .05) higher in the RHN-4 mL animals (0.88 ± 0.03 mg/cm) compared with control (0.74 ± 0.003 mg/cm) and ad libitum chow animals (0.73 ± 0.05 mg/cm). There were no differences in mid- and distal gut mucosal protein levels between groups. We conclude that the rate of enteral feeding has little effect on gut mass in the early (5 day) postoperative period in rats.