Effect of common anti-nutritive factors and fibrous feedstuffs in pig diets on amino acid digestibilities with special emphasis on threonine

¹ Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada, T6G 2P5
² Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL, Canada, A1B 3X9

^* To whom correspondence should be addressed. E-mail: ron.ball{at}ualberta.ca.

	Abstract

Most feedstuffs contain anti-nutritive factors (ANF) such as insoluble fibers, lignins, tannins and lectins. Intake of these ANF has the ability to reduce nutrient digestibility and to increase endogenous protein losses, such as through increased intestinal mucus secretion. The objective of this experiment was to determine the apparent ileal digestibilities (AID) of AA of six ANF-enriched diets to estimate endogenous protein loss associated with these ingredients in diets for young pigs. Forty-two, 10 kg pigs fitted with a simple T-cannula at the distal ileum, were randomly assigned to one of seven casein-based diets with: no supplement (C), 100 g/kg canola meal (CM), 100 g/kg wheat bran (WB), 150 g/kg barley (BR), 22.5 g/kg lignin (LG), 15 g/kg kidney beans (as a lectin source, LE), and 15 g/kg tannins (TN). All diets were formulated to be similar in nitrogen, indispensable amino acid and caloric contents. After a 7-d adaptation to the test diets, nitrogen balance was conducted for 5 d, followed by 24 h of collection of digesta for analyses of AA. Pigs fed BR had 17% lower ADG and 15% lower feed conversion ratio (P < 0.05) compared to C and CM pigs. Pigs fed diets containing WB and BR had lower nitrogen retention as a percent of absorbed nitrogen compared to all other groups (P = 0.03). The AID for CP was lower in BR, WB and LE pigs compared to C. Of the amino acids, AID of Thr was notably lowest in BR, WB and TN pigs (P < 0.05). The standardized ileal digestibility was lower in WB and BR pigs for most indispensable amino acids. Altogether, these data suggest that hemicellulose fiber, at concentrations typical in commercial swine diets, reduces AID of amino acids by increasing endogenous losses. Understanding the differential effects of ANF on endogenous losses of individual dietary AA will improve the accuracy of diet formulation. the differential effects of ANF on endogenous losses of individual dietary AA will improve the accuracy of diet formulation.

Key Words: amino acid digestibility, anti-nutritional factor, fiber, nitrogen balance, pigs, threonine