Pancreatic exocrine secretion in steers infused postruminally with casein and cornstarch.

Our objective was to evaluate the effect of postruminal protein infusion on pancreatic exocrine secretions. One Holstein, two crossbred, and five Angus steers (305 ± 5 kg) with pancreatic pouch-duodenal re- entrant cannulas and abomasal infusion catheters were used in a replicated 4 × 4 Latin square. All steers were abomasally infused with 1,050 g/d of raw cornstarch with treatments of 0, 60, 120, or 180 g/d of sodium casein suspended in water to yield 6,000 g/d of infusate daily. Steers were limit-fed (1.5 × NEm; 12 equal por- tions daily) a 90% corn silage, 10% supplement diet formulated to contain 12.5% CP. Periods consisted of 3 d of adaptation to infusion ,7do ffull infusion ,1do f collection, and 7 d of rest. Pancreatic juice was collected in 30-min fractions continuously for 6 h. Total juice secreted and the pH of individual fractions were re- corded, a 10% subsample was retained to form a com-