585 Digestibility by growing pigs of amino acids in heat-damaged sunflower meal and cottonseed meal 1 F. N. Almeida,* J. K. Htoo,† J. Thomson,‡ and H. H. Stein* 2 *University of Illinois, Urbana 61801; †Evonik Industries AG, Rodenbacher Chaussee 4, 63457 Hanau, Germany; and ‡Evonik Degussa Corporation, Kennesaw, GA ABSTRACT: Two experiments were conducted to determine the effects of heat damage, achieved by auto- claving, on the nutritional composition and on the stan- dardized ileal digestibility (SID) of AA in sunflower meal (SFM) and cottonseed meal (CSM) fed to grow- ing pigs. The second objective was to establish a rela- tionship between the concentration of SID AA in SFM and CSM and the concentration of fiber components, reducing sugars, and AA. In Exp. 1, 10 growing pigs (initial BW: 23.1 ± 1.3 kg) were surgically equipped with a T-cannula in the distal ileum and allotted to a replicated 5 × 5 Latin square design with 5 diets and 5 periods in each square. A common source of SFM was separated into 4 batches that were either not autoclaved or autoclaved at 130°C for 20, 40, or 60 min. Four diets (approximately 14.5% CP) that contained each of the 4 batches of SFM were formulated, and SFM was the only source of CP and AA in the diets. A N-free diet that was used to determine the basal endogenous losses of CP and AA from pigs was also formulated. Each period consisted of 5 d of adaptation to the diets followed by 2 d of ileal digesta collection. The SID of Lys in SFM was reduced (linear, P < 0.05) from 83.2% in nonauto- claved SFM to 63.5% in SFM autoclaved for 60 min at 130°C. The concentrations of total Lys and reducing sugars in SFM may be used as predictors (R 2 = 0.85) of the concentration of SID Lys in SFM. In Exp. 2, 10 growing pigs (initial BW: 35.0 ± 1.5 kg) were surgically equipped with a T-cannula in the distal ileum and allot- ted to a replicated 5 × 5 Latin square design with 5 diets and 5 periods in each square. A source of CSM was separated into 4 batches that were either not autoclaved or autoclaved at 130°C for 15, 35, or 60 min. Four diets (approximately 13.4% CP) containing CSM as the only source of CP and AA were formulated. A N-free diet was also formulated and used as described for Exp. 1. The SID of Lys in nonautoclaved CSM (66.2%) was greater (P < 0.05) than in autoclaved (60 min at 130°C) CSM (54.1%). The equation (R 2 = 0.68) that best pre- dicted the concentration of SID Lys in CSM included the concentration of ADIN. In conclusion, heat damage reduces the SID of AA in SFM and CSM. For SFM, the concentration of SID Lys may be predicted from the concentrations of total Lys and reducing sugars. The concentration of ADIN may be used to predict the con- centration of SID Lys in CSM. Key words: amino acids, cottonseed meal, digestibility, heat damage, pigs, sunflower meal © 2014 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2014.92:585–593 doi:10.2527/jas2013-6769 INTRODUCTION Sunflower meal (SFM) and cottonseed meal (CSM) are protein sources for swine diets (González-Vega and Stein, 2012). Cottonseed meal contains the antinutrition- al factor gossypol, which may be deactivated by heat treatment of the meal, but processes involving heat and moisture may cause Maillard reactions (Nursten, 2005), and the application of heat to feed ingredients may de- crease the concentration, digestibility, and utilization of Lys and other AA (Van Barneveld et al., 1994; Pahm et al., 2008; Boucher et al., 2009; González-Vega et al., 2011). Amino acids that participate in the Maillard reac- tion may become unavailable to pigs and Lys is the AA most susceptible to participate in these reactions (Pahm et al., 2008). Conventional AA analysis of heat-damaged feed ingredients is believed to overestimate the concen- 1 Financial support for this research from Evonik Industries AG is greatly appreciated. 2 Corresponding author: hstein@illinois.edu Received May 31, 2013. Accepted November 25, 2013. Published November 24, 2014