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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2007-0514v1 86/4/909    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Swanson, K. C. Articles by McBride, B. W. Search for Related Content PubMed PubMed Citation Articles by Swanson, K. C. Articles by McBride, B. W.

Pancreatic mass, cellularity, and -amylase and trypsin activity in feedlot steers fed diets differing in crude protein concentration^1,2

Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1

³ Corresponding author: kswanson{at}uoguelph.ca

Twenty-four yearling beef steers (initial BW = 510 ± 4.9 kg) predominantly of Angus breeding were used in a randomized complete block design to determine the effect of dietary CP concentration on pancreatic cellularity, mass, and -amylase and trypsin activities. Treatment diets were formulated to contain 8.8, 11.0, 13.2, and 15.4% CP. Soybean meal and Top Soy (ruminal bypass soybean meal) were used as supplemental protein sources to ensure that MP intake was increased with increasing dietary CP concentrations. Steers were penned in groups of 4 (1 steer per treatment) and individually fed at 2.5x the NE_m requirement by using Calan gates for 28 d before tissue collection. Four steers (1 pen) were slaughtered per week. Pancreases were weighed, subsampled, frozen in liquid N₂, and stored at –80°C until analyses for DNA, RNA, and protein concentrations, and -amylase and trypsin activities. Pancreatic weight (g and g/kg of BW) did not differ among treatment groups. Pancreatic DNA concentration (mg/g) decreased linearly (P = 0.06) with increasing CP concentration. Pancreatic protein (g/pancreas) increased linearly (P = 0.08) with increasing dietary CP concentration. Pancreatic -amylase activity (U/g, U/mg of DNA, U/g of protein, U/pancreas, and U/kg of BW) increased linearly (P 0.04) with increasing dietary CP concentration. Pancreatic trypsin activity (U/g, U/g of DNA, U/g of protein, U/pancreas, and U/kg of BW) increased linearly (P 0.09) with increasing dietary CP concentration. Pancreatic -amylase and trypsin activities (U/mg of RNA) responded quadratically (P 0.09), with the greatest -amylase activity observed in the 13.2% CP treatment. These data indicate that increasing dietary CP concentration decreases pancreatic cell numbers and also increases the concentration and content of pancreatic -amylase and trypsin activities. Changes in cell number and size may be important factors regulating digestive enzyme production in the pancreas of cattle.

Key Words: beef cattle • pancreas • -amylase • trypsin • dietary protein