Influence of ruminal or abomasal starch hydrolysate infusion on pancreatic exocrine secretion and blood glucose and insulin concentrations in steers

Seven Holstein steers (234 +/- 6.4 kg) surgically fitted with pancreatic cannulas, ruminal and abomasal infusion cannulas, and hepatic-portal vein catheters were used in a 4 x 7 incomplete Latin square design experiment to examine the influence of ruminal and abomasal carbohydrate infusion on enzyme secretion and composition of pancreatic juice. Four treatments were arranged in a 2 x 2 factorial: 1) ruminal starch hydrolysate (SH; 34.2 g/[h.site]) or abomasal water and 2) abomasal SH or ruminal water. Starch hydrolysate is raw cornstarch that has been partially digested by a heat-stable alpha-amylase. Experimental periods were 14 d with 9 to 10 d of adaptation, 4 d of pancreatic collection, and blood collection on d 14. Abomasal SH infusion tended (P < .10) to increase pancreatic fluid secretion. The pH of pancreatic juice was higher (P < .01) for ruminal SH infusion, and abomasal SH infusion tended (P < .10) to result in lower pH of pancreatic juice. alpha-Amylase concentrations (units/milliliter and units/milligram of protein) and secretion (units/hour) were less (P < .002) for abomasal SH infusion. Chymotrypsin concentration (units/liter; P < .01) and secretion (units/hour; P < .10) were less for abomasal SH infusion; however, a rumen x abomasal interaction was found (P < .05). Chloride concentration (milligrams/deciliter) and secretion (milligrams/hour) were increased (P < .01) for abomasal SH infusion. Abomasal SH infusion resulted in increased (P < .01) portal blood glucose concentrations; however, portal plasma insulin concentration was not affected (P > .10). Abomasal SH infusion altered alpha-amylase secretion in steers, but ruminal SH infusion had minimal effect on alpha-amylase secretion. These changes suggest abosamal infusion of SH may negatively impact secretion of pancreatic alpha-amylase.