Quality Control Parameters for Commercial Full-Fat Soybeans Processed by Two Different Methods and Fed to Broilers

Transcription

1 2004 Poultry Science Association, Inc. Quality Control Parameters for Commercial Full-Fat Soybeans Processed by Two Different Methods and Fed to Broilers N. Ruiz,*,1 F. de Belalcázar, and G. J. Díaz ContiGroup Companies, ContiTec Unit, PO Box 2989 Suwanee, Georgia 30024; Nutrianálisis Ltda., calle 22C No 44A-12, Santafé de Bogotá, Colombia; and Facultad de Medicina Veterinaria y de Zootecnia, Universidad Nacional de Colombia, Santafé de Bogotá, Colombia Primary Audience: Nutritionists, Formulators, Poultry Producers, Quality Assurance Personnel, Researchers SUMMARY Full-fat soybean (FFSB) samples obtained from 2 experiments already published were analyzed in vitro for urease activity (UA), Soy-Chek score, trypsin inhibitor (TI) activity, and KOH protein solubility (KOHPS). Samples were also analyzed in vivo for amino acid digestibility using the precision-fed cecectomized rooster assay at the University of Illinois. Samples from experiment 1 corresponded to 6 temperature treatments in a commercial extruder: raw, 118, 120, 122, 126, and 140 C. Samples from experiment 2 corresponded to 6 temperature treatments along with different retention times in a commercial toaster: raw, 113, 120, 130, 135, and 150 C, and 0, 3.0, 4.5, 6.5, 7.0, and 9.5 m, respectively. In vitro results were compared with the already published performance data. The TI and UA were significantly (P < 0.05) correlated to BW and feed conversion ratio in both experiments. There was no correlation in any experiment between KOHPS and performance data, except for feed conversion ratio in experiment 1. Less than 18,000 TI units/g or less than 0.10 ph units of UA are adequate for optimum broiler chicken performance. Both performance and in vivo amino acid digestibility data failed to demonstrate that FFSB were overprocessed in any of the experiments, even though solubility values dropped as temperature treatment increased. Key words: amino acid digestibility, broilers, full-fat soybeans, protein solubility, trypsin inhibitors, urease activity 2004 J. Appl. Poult. Res. 13: DESCRIPTION OF PROBLEM Considerable knowledge has been accumulated over the years to quantify the need and the effects of heat treatment in soybean meal (SBM) for animal feeding [1, 2, 3]. Although full-fat soybeans (FFSB) as an animal feed ingredient may appear fairly related to SBM, in practice FFSB is a different ingredient with different nutritional composition and processing conditions than SBM. Therefore, in the quality control (QC) of FFSB processing, the parameters are not necessarily the same as those used to estimate optimum SBM quality. 1 To whom correspondence should be addressed: nelson.ruiz@contilatin.com.

2 444 Matrai and coworkers [4], as well as Waaijenberg [5], have reported practical QC parameters for FFSB, which are specified according to the intended animal species and age of feeding. However, limited information is available correlating specific QC or in vitro estimators with actual performance of broiler chickens to market age. Therefore, the objective of this paper is to correlate in vitro determinations in representative samples of FFSB used in in vivo feeding trials with broiler chickens. MATERIALS AND METHODS Two different experiments were conducted at the National University of Colombia to determine the optimum processing conditions to produce commercial FFSB by 2 different methods: wet-extrusion and dry toasting. In both experiments treatments consisted of raw soybeans processed at different temperatures and lengths of time, formulated in a single broiler mash feed and fed to broiler chickens from 1 to 42 d of age. In experiment 1, the composition of the experimental diets was 54.84% yellow corn, 41.28% FFSB, and 0.39% soybean oil, and the balance was minerals, vitamins, choline chloride, and DL-methionine. Diets were formulated to contain 3,298 kcal/kg of ME, 20.0% CP, 0.87% TSAA, 1.10% total lysine, 1.0% calcium, and 0.45% available phosphorus. In experiment 2, the composition of the experimental diets was 41.0% yellow corn, 42.3% FFSB, 8.0% wheat middlings, 4.0% unextracted rice bran, and the balance was minerals, vitamins, choline chloride, DL-methionine, and L- lysine HCl. Diets were formulated to contain 3,080 kcal/kg of ME, 19.4% CP, 0.83% TSAA, 1.14% total lysine, 1.04% calcium, and 0.42% available phosphorus. The design, results, and conclusions for each of these experiments are published elsewhere [6, 7]. Representative samples of the FFSB used in each treatment of the 2 experiments were obtained to run in vitro testing and correlate these results with the published performance of broilers at 42 d of age. Additionally, results of in vivo amino acid digestibility conducted for each FFSB sample are also discussed in the context of the performance data. JAPR: Research Report FFSB Samples from Experiment 1 In experiment 1 [6], FFSB were wet-extruded in an Anderson expander-extrudercooker [8] at 118, 120, 122, 126, and 140 C. The mean residence time was 20 s. The raw soybeans contained 91.6% DM, 20.5% ether extract, 36.9% CP, 6.1% crude fiber, and 4.9% ash. Diets containing raw FFSB and solvent extracted soybean meal were also included in this experiment as negative and positive controls, respectively. FFSB Samples from Experiment 2 In experiment 2 [7], FFSB were toasted in a thermal processor for FFSB and cereals designed and installed at Soyagro Ltd. [9] at 113, 120, 130, 135, and 150 C. In this specific toaster, the residence time is adjusted to each temperature by modifying the inclination of the toasting chamber. Residence times were 3.0, 4.5, 6.5, 7.0, and 9.5 m, respectively, for the 5 temperatures. The raw soybeans contained 91.1% DM, 19.5% ether extract, 37.9% CP, 4.4% crude fiber, and 5.3% ash. A diet containing raw FFSB was also included in this experiment as a negative control. In Vitro Analysis Urease activity (UA) was determined in all FFSB samples and the soybean meal sample by the ph rise method, Ba 9-58 [10]. All samples were also tested by the quick Soy-Chek method [11]. Trypsin inhibitor (TI) activity was determined in all samples using method Ba [12]. Protein solubility in potassium hydroxide (KOH) at 0.2% was determined in all samples according to the procedure published by Dale and coworkers [13]. The particle size determination in FFSB samples and soybean meal sample in experiment 1 was determined by the geometric diameter method [14]. Proximate Analysis Crude protein and DM were determined in all samples. Ash, crude fiber, and crude fat were determined in the raw FFSB and soybean meal samples. All analyses were conducted by wetchemistry (AOAC) [15].

3 RUIZ ET AL.: FULL-FAT SOYBEAN QUALITY 445 TABLE 1. In vitro analyses of wet-extruded full-fat soybeans (FFSB) and soybean meal (SBM) and comparison with broiler performance data per Perilla et al. [6], experiment 1 Trypsin KOH BW Urease inhibitor protein gain, Feed Treatment A Moisture activity Soy-Chek activity solubility 8 to 42 d conversion ( C) (%) (ph units) score B (TI units/g) (%) (g) ratio Raw , ,502 c , ,890 b , ,897 b , ,056 a , ,067 a , ,987 ab 1.71 SBM , ,028 a 1.6 a c Means within the same column with no common superscripts differ significantly (P < 0.05). A Wet-extrusion conducted in an Anderson expander-extruder-cooker. B Soy-Chek score per table of interpretation provided in each bottle of the reagent. These scores for FFSB were obtained at 10 min after addition of the reagent. For SBM the reaction time was 5 min. According to LSB Products (Manhattan, KS), a score of 1 correlates with ph rise of approximately 2.0. A score of 2 correlates with ph rise = 0.3 to 0.5. A score of 3 correlates with ph rise = 0.1 to A score of 4 correlates with ph rise = 0.05 to A score of 4.5 correlates with ph rise = 0.02 to 0.05, and a score of 5 correlates with ph rise = 0.0. The score values shown above do not correspond exactly with LSB indications, but scores between 4.5 and 5 correlated well with maximum performance. In Vivo Analysis All samples were analyzed at the University of Illinois for true digestible amino acids according to the method of Sibbald [16] as described by Anderson-Hafermann et al. [17]. All amino acid analyses were conducted at the Amino Acid Laboratory of Degussa Corporation [18], using AOAC method [19]. Statistical Analysis Pearson correlation coefficients were computed for TI activity, urease activity, and KOH protein solubility using a commercially available software package [20]. RESULTS AND DISCUSSION In Vitro Data Versus Growth Data, Experiment 1 The growth data from Perilla et al. [6] show that BW gain (Table 1) between 8 and 42 d was not significantly different for the 122, 126, and 140 C treatments. The BW obtained with these 3 treatments were not significantly different than for the soybean meal treatment. However, feed conversion was more efficient in the SBM treatment. The raw soybeans treatment was significantly different than the 118 and 120 C treatments, confirming the improvement in animal performance due to heating of soybeans. The BW and feed conversion data indicate that performance was maximized for treatments 122, 126, and 140 C. Trypsin inhibitor activity dropped consistently from 50,800 (raw FFSB) to 4,700 TI units/ g as temperature treatment increased to 140 C (Table 1). The 17,700 to 4,700 range for treatments 122, 126, and 140 C appears consistent with the 14,000 to 7,000 TI units/g range considered typical in the US [21] for adequately processed FFSB. Urease activity as measured by the ph rise method is another in vitro test widely used by industry to assess the adequacy of heat treatment of SBM and FFSB. Raw soybeans and treatments 118 and 120 C had the highest UA values, which corresponded to suboptimal bird performance (Table 1). In this experiment the range of ph values that corresponded with maximum performance was 0.07 to 0.03 ph units for treatments 122, 126, and 140, respectively. Soy-Chek is a trademark for a ready-to-use color test to evaluate UA. It was included as another in vitro test because it is fairly well correlated to ph rise and because it is a very quick and simple test to run. The data for Soy- Chek in Table 2 indicate that this quick method clearly differentiated the underprocessed FFSB treatments from the adequate ones. The Soy- Chek manufacturer indicates that the product is applicable to both SBM and FFSB; however,

4 446 JAPR: Research Report TABLE 2. Total amino acid values (percentage at 88% DM) in full-fat soybeans and soybean meal (SBM) samples, experiment 1 Treatment ( C) Threonine Cystine Valine Methionine Isoleucine Leucine Lysine Arginine Tryptophan Raw SBM for FFSB the time to evaluate results is 10 min as opposed to SBM for which the time is 5 min. It is possible that the fat content in FFSB slows the wetting of the sample by the reagent. All of the above in vitro tests are valid to detect underprocessing, that is, insufficient heating of SBM or FFSB. The results for TI and UA in Table 1 follow similar trends as those reported by Perilla et al. [6] on different samples of the same treatments and conducted in a different laboratory. The KOH protein solubility (KOHPS) test has been suggested as a method to evaluate overprocessing, that is, excessive heat treatment of SBM [13, 22, 23] and other oilseed meals. With the exception of the report by Perilla and coworkers [6], we are not aware of specific publications evaluating the value of the KOHPS test to predict overprocessing for FFSB. The data for KOHPS in Table 1 show that solubility was above 90% for raw soybeans, which is in agreement with the data of Anderson- Hafermann et al. [17]. For the heat treatments, all values were in the upper 80s with only the treatment of 140 C at 79%. The KOHPS data (Table 1) do not agree with the data reported by Perilla et al. [6] on different samples of the same treatments since they reported solubilities as low as 72 and 67% for treatments 126 and 140 C, respectively. However, it is important to emphasize that a major limitation of the solubility test is that it is very empirical with various factors, such as the particle size of SBM [24] or FFSB, and agitation intensity [25] among other factors affecting the interlaboratory variability for the test. For the FFSB samples used for this report, the average particle size expressed as the average geometric diameter ranged from 480 to 650 µm, whereas for the SBM sample it was 250 µm. The FFSB samples do not grind very well in laboratory mills because of its oil content. In Vivo Amino Acid Digestibility Versus Growth Data, Experiment 1 Total amino acid (TAA) values standardized at 88% DM are presented in Table 2. Although 1 single analysis was run for each sample, it should be noted that the FFSB treatments were all derived from the same original lot of raw soybeans. Except when overprocessing conditions occur, TAA values are normally not affected by processing. Therefore, for practical purposes the TAA values for the different treatments are 6 replicated analyses. As temperature increased during wet-extrusion, the digestible amino acid (DAA) coefficients (Table 3) increased, indicating the gradual destruction of TI and other antinutritional factors that may affect amino acid absorption. The highest numerical values for DAA coefficients were obtained at 126 C. However, because each DAA coefficient was determined with a single set of birds (3 birds) per sample, and excreta were pooled together for 1 analysis, there is no variability data to statistically differentiate treatments 122, 126, and 140 C as far as DAA coefficients are concerned. Nevertheless, the performance data from [6] shown in Table 1 were not statistically different for these 3 treatments, and, consequently, it is possible to infer that the small variation among the DAA coefficients for these 3 treatments was not enough to change performance. Although in general there was a small decrease in the DAA coefficients for the 140 C treatment relative to the 126 C treatment, performance data do not support the concept of overprocessing in the experiment of Perilla et al. [6].

5 RUIZ ET AL.: FULL-FAT SOYBEAN QUALITY 447 TABLE 3. Digestible amino acid coefficients (%) for full-fat soybeans and soybean meal (SBM) samples, experiment 1 Treatment ( C) Threonine Cystine Valine Methionine Isoleucine Leucine Lysine Arginine Tryptophan Raw SBM The effects of overprocessed SBM on broiler performance are well documented [13, 22, 23], digestible lysine being the single most damaged amino acid [26, 27]. However, an additional indication of overprocessing is the net destruction of total lysine [26], which could also be expected to occur in overprocessed FFSB, and it was not observed for treatment 140 C (Table 2). In Vitro Data Versus Growth Data, Experiment 2 The growth data from Ordoñez and Palencia [7] show that the BW at 42 d of age (Table 4) were not significantly different for the 120, 130, 135, and 150 C treatments. The BW for the raw soybean and 113 C treatments were significantly different (P < 0.05). The highest numeri- cal BW at 42 d was for the 130 C treatment, followed by the 120 C treatment. The TI activity dropped dramatically from raw FFSB to the 113 C treatment, that is, from 56,300 to 8,850 TI units/g (Table 4). Thereafter, additional heating (higher temperatures and longer residence times) resulted in a smooth decrease of the TI activity. The UA also dropped dramatically from 2.01 to 0.03 ph units at the 113 C treatment, and Soy-Chek also reflected the large drop in UA at 113 C (Table 4). Soy-Chek data were consistent with ph rise data. The KOHPS data in Table 4 show a consistent decrease in the protein solubility of FFSB as temperature and retention time increased. All of the in vitro data changes corresponded with an improvement in the BW of broilers at TABLE 4. In vitro analyses of dried toasted full-fat soybeans and comparison with broiler performance data per Ordoñez and Palencia [7], experiment 2 Treatment A KOH ( C) and Trypsin inhibitor protein Feed retention time Moisture Urease activity Soy-Chek activity solubility BW at conversion (min) (%) (ph units) score B (TI units/g) (%) 42 d (g) ratio Raw , ,118 c min , ,802 b 1.81 a min , ,972 a 1.80 a min , ,030 a 1.71 a min , ,946 ab 1.79 a min , ,943 ab 1.78 a a c Means within the same column with no common superscripts differ significantly (P < 0.05). A Dry toasting conducted in a thermal processor for full-fat soybeans (FFSB) and cereals toaster. B Soy-Chek score as described in Table 1.

6 448 JAPR: Research Report TABLE 5. Total amino acid values (percentage at 88% DM) in full-fat soybeans (FFSB) samples, experiment 2 Treatment ( C) Threonine Cystine Valine Methionine Isoleucine Leucine Lysine Arginine Tryptophan Raw d up to the 130 C treatment. However, as discussed in the next paragraphs, the growth data for the 113 C treatment cannot be explained with the in vitro data obtained for the FFSB sample of that treatment. In Vivo Amino Acid Digestibility Versus Growth Data, Experiment 2 The amino acid values standardized at 88% DM are presented in Table 5. As in the case of experiment 1, 1 TAA analysis was conducted per sample, but because the 6 samples of this experiment are derived from the same original lot of raw soybeans, the TAA values in Table 5 are very similar, demonstrating that there was no damage to any of the 9 analyzed TAA as a consequence of dry toasting. As temperature and retention time increased during dry toasting, the DAA coefficients (Table 6) of FFSB increased to reach a numerical maximum at the 130 C treatment with very slight changes for the 135 and 150 C treatments. As already indicated and shown in Table 4, the maximum performance in the experiment of Ordoñez and Palencia [7] was obtained with the 130 C treatment. Therefore, the growth data ran parallel with the increased DAA coefficients as a consequence of toasting. Did the in vitro data predict in vivo performance of broilers fed FFSB in the 2 experi- ments? We have to divide the answer to this question in 2: underprocessing, that is, the detection of insufficient heating, and overprocessing, that is, excessive heat treatment. Underprocessing For both experiments [6, 7] the TI activity and the UA of the FFSB samples analyzed were significantly correlated with the performance parameters evaluated (Table 7). The TI and UA were negatively correlated with BW and positively correlated with feed conversion ratio. These high correlation values suggest that these parameters are accurate predictors of the quality of FFSB. In experiment 1, TI activity below 18,000 TI units/g coincided with a ph rise value below 0.10 ph units for the 122, 126, and 140 C treatments, which, in turn, were not significantly different among them and not significantly different than the SBM positive control. In experiment 2, the only exception is for the in vitro data for the 113 C treatment, which do not predict the significantly lower BW of broilers at 42 d, since TI activity was only 8,850 TI units/g, and ph rise was not higher than 0.03 ph units. However, a review of the in vivo DAA coefficients (Table 6) suggests that indeed the FFSB dry toasted at 113 C showed a pattern of overall lower digestibilities typical of underprocessed FFSB. In other words, the in vivo DAA TABLE 6. Digestible amino acid coefficients (%) for full-fat soybeans (FFSB) samples, experiment 2 Treatment ( C) Threonine Cystine Valine Methionine Isoleucine Leucine Lysine Arginine Tryptophan Raw

7 RUIZ ET AL.: FULL-FAT SOYBEAN QUALITY 449 TABLE 7. Pearson correlation coefficients between in vivo parameters in broiler chickens (BW and feed conversion ratio) and in vitro quality control analyses in full-fat soybeans (FFSB) processed by 2 different methods Experiment 1, Experiment 2, wet-extruded FFSB toasted FFSB BW gain, Feed conversion Feed conversion d 8 to 42 ratio BW at 42 d ratio Trypsin inhibitor activity (U/g) 0.91* 0.93** 0.98** 0.99** Urease activity (ph U) 0.85* 0.82* 0.98** 0.99** KOH solubility (%) * NS NS NS *P < 0.05; **P < coefficients data help to explain the suboptimal performance of broilers fed FFSB dry toasted at 113 C. We do not have an explanation for this inconsistency. Otherwise, the concept of TI activity of less than 18,000 TI units/g and UA activity lower than 0.10 ph units also applies to dry toasting of FFSB to maximize performance. Overprocessing The only in vitro criteria used in the evaluation of the FFSB samples for the 2 experiments was the protein solubility in KOH. However, neither the growth data nor the in vivo DAA coefficients support the concept that overprocessing of FFSB occurred in either of the 2 experiments [6, 7]. Therefore, no significant correlations were found between KOH protein solubility and the performance parameters evaluated except for feed conversion ratio in experiment 1 (Table 7). This is an unexpected finding because of the widespread use of KOHPS to assess the overprocessing status of SBM. Although the validity of KOHPS has been documented mostly in laboratory models [22, 23, 27], it also has been tested with commercial SBM having different solubilities. Kang and coworkers [28] fed broilers to 3 wk with commercial soybean meals, which differed in 15 points (percentage units) of KOHPS values. The BW at 21 d showed a difference of 5.75% between the highest and the lowest solubilities. A controlled experiment conducted by Lee and coworkers [29] with a commercially overprocessed soybean meal demonstrated that a 10-point drop in solubility resulted in a significant growth depression of about 170 g in growing turkeys at 9 wk of age. Therefore, there is sufficient evidence on the value of KOHPS to detect overprocessed SBM, but the results of the 2 experiments with FFSB analyzed here do not support that overprocessing was detected in vivo. Even though there was a drop in solubility of 19 points in experiment 1 (98 vs. 79%) and 25 points in experiment 2 (94 vs. 69%), these decreases did not reflect overprocessing of FFSB. It is possible that the value of protein solubility at which it becomes correlated with overprocessing of FFSB is much lower than in SBM. Anderson-Hafermann et al. [30] found that processing of canola seeds to generate canola meal may result in canola meals displaying a wide range of KOHPS values from 80 to 40%, but only solubilities below 40% are correlated with overprocessing. A similar effect was reported by Jensen et al. [31] in rapeseed meals. The relevance of the data from the 2 experiments with FFSB [6, 7] is that in both experiments each FFSB processor (the Anderson expander and the thermal processor) were used beyond their normal operating conditions to generate the highest temperature treatment in each experiment. Therefore, this is a suggestion that overprocessing of commercial FFSB may be a difficult task. CONCLUSIONS AND APPLICATIONS 1. The results of the 2 experiments analyzed here allowed the conclusion that in the QC of commercial FFSB less than 18,000 TI units/g or less than 0.10 ph units of UA are adequate

8 450 JAPR: Research Report to generate FFSB of optimum quality as reflected by broiler chicken performance. Both TI and UA are accurate predictors of the quality of FFSB. 2. Although the protein solubility coefficients in KOH did decrease as a consequence of the increasing heat treatment of FFSB in 2 commercially available processors, no evidence of overprocessing was found in vivo. 3. Because overprocessing of FFSB did not occur in either of the 2 experiments, it was not possible to establish the value at which KOHPS correlates with the overprocessing of this ingredient. 1. Carvens, W. W., and E. Sipos Soybean oil meal. Pages in Process Plant Protein Foodstuffs. A. M. Altschul, ed. Academic Press, New York. 2. Liener, I. E Effect of heat on plant proteins. Pages in Process Plant Protein Foodstuffs. A. M. Altschul, ed. Academic Press, New York. 3. Balloun, S. L Soybean Meal in Poultry Nutrition. American Soybean Association, St. Louis, MO. 4. Matrai, T., S. Kokai, and I. Salamon Practical quality control of full-fat soybean meal. Pages in Second Int. Fullfat Soya Conf., Budapest, Hungary. 5. Waaijenberg, A Experiences with fullfat soya in animal feed. Pages in Second Int. Fullfat Soya Conf., Budapest, Hungary. 6. Perilla, N. S., M. P. Cruz, F. de Belalcazar, and G. J. Díaz Effect of temperature of wet extrusion on the nutritional value of full-fat soyabeans for broiler chickens. Br. Poult. Sci. 38: Ordoñez, L. F., and J. C. Palencia Efecto de diferentes temperaturas de tostado seco sobre la calidad nutricional del fríjol soya integral empleado en alimentación de pollos de engorde. Thesis. National University of Colombia, Santafé de Bogotá. 8. Anderson International Corp. Cleveland, OH. 9. Mario Tobar and Arturo Watemberg. Barranquilla, Colombia. 10. American Oil Chemists Society Official and Tentative Methods of the American Oil Society, 3rd ed. Official Method Ba 9-58, American Oil Chemist Society, Champaign, IL. 11. LSB Products, 731 McCall Road, Manhattan, KS. 12. American Oil Chemists Society Official method Ba in Official and Tentative Methods of the American Oil Society. 3rd ed. American Oil Chemist Society, Champaign, IL. 13. Dale, N. M., M. Araba, and E. Whittle Protein solubility as an indicator of optimum processing of soybean meal. Pages in Proc. Georgia Nutr. Conf. for the Feed Ind., Atlanta. 14. American Society of Agricultural Engineers Methods for determining and expressing fitness of feed materials by sieving. Page 325 in American Society of Agricultural Engineers Standard S319. ASAE Yearbook of Standards, St. Joseph, MI. 15. Association of Official Analytical Chemists Official Methods of Analysis. 15th ed. AOAC, Arlington, VA. 16. Sibbald, I. R A bioassay for available amino acids and true metabolizable energy in feedstuffs. Poult. Sci. 58: Anderson-Hafermann J. C., Y. Zhang, and C. M. Parsons Effect of heating on nutritional quality of conventional and Kunitz trypsin inhibitor-free soybeans. Poult. Sci. 71: Degussa Corporation. Amino Acid Laboratory, Applied Technology Chemical Group, Allendale, NJ. REFERENCES AND NOTES 19. Llames, C. R., and J. Fontaine Determination of amino acids in feeds: Collaborative study. J. AOAC Int. 77: Statistix for Windows Version 2.0. Analytical Software. Tallahassee, FL. 21. McBride, D. W., Woodson-Tenent Laboratories, Inc., Des Moines, IA, personal communication. 22. Araba, M., and N. M. Dale Evaluation of protein solubility as an indicator of overprocessing soybean meal. Poult. Sci. 69: Parsons, C. M., K. Hashimoto, K. J. Wedekind, and D. H. Baker Soybean protein solubility in potassium hydroxide: An in vitro test of in vivo protein quality. J. Anim. Sci. 69: Whittle, E., and M. Araba Sources of variability in the protein solubility assay for soybean meal. J. Appl. Poult. Res. 1: Ruiz, N Avances en la estandarización delatécnica de la solubilidad de la proteína en KOH. Pages 1 8 in Memorias del Seminario Internacional Nutrición Integral Aviar de Cara al Siglo XXI, Santafé de Bogotá, Colombia. 26. Parsons, C. M., K. Hashimoto, K. J. Wedekind, Y. Han, and D. H. Baker Effect of overprocessing on availability of amino acids and energy in soybean meal. Poult. Sci. 71: Aburto, A., M. Vazquez, and N. M. Dale Strategies for utilizing overprocessed soybean meal: II. Lysine supplementation. J. Appl. Poult. Res. 7: Kang, C. W., K. T. Nham, Y. J. Joo, and K. R. Kang Evaluation of nutritional quality of soybean oil meals as poultry feedstuffs in Korea. Research Report. American Soybean Association, St. Louis, MO. 29. Lee, H., J. D. Garlich, and P. R. Ferket Effect of overcooked soybean meal on turkey performance. Poult. Sci. 70: Anderson-Hafermann, J. C., Y. Zhang, and C. M. Parsons Effects of processing on the nutritional quality of canola meal. Poult. Sci. 72: Jensen, S. K., Y. G. Liu, and B. O. Eggum The effect of heat treatment on glucosinolates and nutritional value of rapeseed meal in rats. Anim. Feed Sci. Technol. 53: Acknowledgments The authors would like to express their appreciation to Carl Parsons, University of Illinois, for his diligence in conducting in vivo DAA coefficients; to Cynthia Llames, Degussa Corporation, for conducting all of the amino acid analyses, and to ContiGroup Companies, Inc., for making possible the collaboration among the authors.