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PROTEIN DIGESTION BY WEANLING PIGS
Abstract
Three experiments were conducted to investigate protein digestion and absorption in pigs weaned at 3 wk of age using a total digesta collection procedure when pigs reached 5 wk of age. In Exp. 1, a 22% CP corn-soybean meal (SBM) diet containing chromic oxide and PEG as nonabsorbable markers was offered ad libitum to 6 pigs, while another 6 pigs were fed a similar amount of the same diet in 4 equal meals per day. There were no differences in apparent N digestibility, flow rates and retention times of the particulate and soluble fractions of the digesta or N due to feeding method. More than 80% of the soluble protein in the stomach and 65% in the small intestine was between 2 and 15,000 molecular weight (MW). In Exp. 2, endogenous N secretion was estimated by feeding a protein-free (PF) diet offered ad libitum to 8 pigs. A SBM control diet was also fed to 8 pigs. Flow rates of total endogenous N were: 1.1, 6.3, 4.0, 5.1, 2.3, 3.1, 3.4 and 3.4 g N/kg DM intake for the stomach, duodenum, jejunum, ileum, cecum, proximal colon, distal colon and rectum, respectively. Molecular weight profiles of the soluble protein as a proportion of the total soluble protein were similar for pigs fed SBM and PF diets and resembled the MW profiles in the stomach and small intestine of the pigs used in Exp. 1. This suggests that most of the endogenous enzymes are hydrolyzed rapidly, as little soluble protein corresponding to the MW of the pancreatic enzymes was found. In Exp. 3, corn-based diets supplemented with dried skim milk (DSM), SBM or corn gluten meal (CGM) were offered ad libitum to 6 pigs per treatment. Flow rates of DM, total N and the particulate fraction of the digesta were higher (P $<$.05) in pigs fed DSM than those fed SBM. The amount of soluble protein as a percentage of total N and apparent N digestibilities in the stomach were highest for pigs fed DSM, intermediate for pigs fed SBM (P $<$.05) and lowest for pigs fed CGM (P $<$.001). Soluble proteins from 10 to 100,000 MW were higher (P $<$.05) in the stomach and small intestine of pigs fed DSM than those fed SBM. Free amino acids and soluble proteins from 2 to 100,000 MW were lower (P $<$.05) in the small intestine of pigs fed CGM than those fed DSM and SBM. Protein solubility and the rate of proteolysis in the stomach and upper small intestine limited the digestion of SBM and especially CGM compared to DSM.
Subject Area
Livestock
Recommended Citation
ASCHE, GARY LEE, "PROTEIN DIGESTION BY WEANLING PIGS" (1987). ETD collection for University of Nebraska-Lincoln. AAI8717246.
https://digitalcommons.unl.edu/dissertations/AAI8717246