Document Type

Thesis - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)


Animal Science

First Advisor

Richard C. Wahlstrom


Three experiments were conducted using a total of 30 young weaned pigs, surgically fitted with simple T-cannula at the terminal ileum, to evaluate the effects of dietary crude protein (CP) and fiber on the ileal and fecal digestibilities of various dietary fractions. Pigs (avg wt, 7.9 kg) were rotated through a series of diets in crossover designs. Experiment 1 addressed the effect of 12.2, 17.2 and 20.8% dietary CP on ileal and fecal digestibilities of dietary dry matter (DM), nitrogen, amino acids, neutral detergent fiber (NDF), acid detergent fiber, crude fiber, cellulose, hemicellulose lignin and ash. With increasing dietary CP ileal and fecal DM digestibility decreased (P<.03) while nitrogen, amino acid, NDF, acid detergent fiber, crude fiber, cellulose, hemicellulose, lignin and ileat ash digestibilities all improved (P<.05). There appeared to be a plateau at 17.2% cp where depression in DM digestibilities and improvements in nitrogen and amino acid digestibilities were no longer significant (P<.05). In experiment 2 the effects of dietary fiber on the digestibility of various dietary fractions was studied. Dietary NDF concentrations were 20.5, 24.5 and 30.5%. Crude protein was held constant at 20.8%. Increased dietary NDF depressed (P<.05) DM digestibility and ileal amino acid measures but did not affect (P>.05) nitrogen, NDF, hemicellulose and ash digestibilities. Acid detergent fiber, cellulose and lignin digestibilities improved (P<.04) due to increasing dietary NDF. In experiment 3, a factorial arrangement of 2 CP (18.6 and 24.4%) and 2 NDF (10.8 and 23.2%) concentrations were studied. Increasing dietary NDF had a negative effect (P<.05) on all dietary component digestibilities measured except lignin. Dietary NDF depressed (P<.05) amino acid digestibilities over the entire digestive tract but depressed only histidine, lysine, glycine and serine when measured at the ileum. Crude protein improved (P<.05) ileal and fecal nitrogen digestibility with little affect on amino acid digestibilities. Fecal digestibilities of all dietary fractions measured improved with time. Results suggest the young weaned pig is able to make limited use of fibrous diets without greatly affecting other dietary component digestibilities. Also, it may be possible to lower CP content below recommended CP concentrations without adversely affecting digestibilities. Increasing fecal digestibility coefficients over time brings to question the time period (age) at which it becomes important to use cannulated pigs for apparent digestibility measures.

Library of Congress Subject Headings

Swine -- Feeding and feeds

Proteins in animal nutrition

Fiber in animal nutrition



Number of Pages



South Dakota State University