Ileal Digestibilities of Amino Acids in Wheat Shorts for Growing Pigs

Suxi Huang, Willem Sauer and Bruno Marty

Alberta Pork Research Centre; Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada T6G 2P5

The problem with the use of wheat shorts in diets for swine is the lack of uniformity due to variable proportions of endosperm and bran particles. An increase in the proportion of bran particles will increase the fiber content and decrease the digestible amino acid content. The objectives of these studies were to determine the apparent ileal digestibilities of amino acids in different samples of wheat shorts and the relationships between the digestibilities and neutral-detergent fiber (NDF) contents.

Six barrows, average initial body weight (BW) 37.2 kg, were fitted with a simple T-cannula at the distal ileum. After recuperation, the barrows were fed one of six experimental diets according to a 6 × 6 Latin square design. Six diets were formulated to contain 17% CP. Diets A, B, C, D and E contained 17.53% soybean meal (SBM), which contributed 50% CP to these diets. The wheat fractions contained wheat shorts (WS), wheat bran (WB) or wheat flour (WF) alone or in combination, which contributed the remaining 50% CP to these diets. Diet F contained 35.05% SBM, which was the sole source of dietary CP. The proportions of WS, WB and WF in the wheat fractions were 70% WS and 30% WB in diet A, 85% WS and 15% WB in diet B, 100% WS in diet C, 85% WS and 15% WF in diet D and 70% WS and 30% WF in diet E.

The apparent ileal digestibility values of amino acids in the wheat fractions were calculated using the difference method. The digestibilities were usually lower in wheat fractions A, B and C than in D and E. Of the indispensable amino acids within each wheat fraction, the digestibilities were usually highest for arginine, histidine and methionine and lowest for lysine and threonine. The digestibilities of lysine ranged from 54.7 to 64.1%, while the digestibilities of threonine ranged from 48.9 to 69.2%. The content of NDF in the wheat fractions ranged from 29.5 to 42.3%. Simple linear relationships were established between the NDF or NDF-associated nitrogen (NDF-N) content and apparent ileal amino acid digestibilities in the wheat fractions. For most amino acids, there were significant (P < .05) negative correlations between the NDF or NDF-N content and apparent ileal amino acid digestibilities.

Implication: The simple linear regression equations established in these studies can be used to predict the digestibilities of amino acids in different wheat shorts according to the NDF contents, therefore, this ingredient can be used more effectively in the formulation of diets for swine by producers and feed manufacturers.