Technical and commercial information on Animal Feed. Feed Formulation. Extrusion, Pelletizing, Feedstuffs, Forage and Probiotics in animal nutrition.

Animal Feed

Nelson Ruiz

Dr. Nelson Ruiz shares with Engormix members his research on this quantitative approach to improve feed formulation, presented at the International Poultry Scientific Forum at IPPE 2022 in Atlanta.



Soybean meal, digestible amino acids and KOH protein solubility test

Feed formulation

Feedstuffs

Energy in poultry diets

Amino acids in poultry nutrition

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	<strong>Standardization of the KOH protein solubility test for soybean meal in a single commercial laboratory and correlation to in vivo poultry amino acid digestibility</strong></div>
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	<strong>Abstract</strong></div>
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	The KOH protein solubility (KOHPS) test is used to evaluate whether a lot of commercial soybean meal (CSBM) has undergone the Maillard reaction during processing. The method was introduced to the animal feed industry in 1990 by Araba and Dale and is widely used worldwide. However, there are at least two limitations to this important measure of CSBM quality that are still poorly explained: First, Iarge inter-lab variability is routinely observed. Second, nutritionists and formulators are unable to estimate the amino acid digestibility (AAD) for lysine (LYS) and arginine (ARG) in lots of CSBM affected by the Maillard reaction because a quantitative interpretation of the results in terms of AAD has not been developed. The objective of this study was to standardize the KOHPS test in a single commercial lab starting from the description by Araba and Dale (1990), utilizing CSBM samples for which the in vivo MD was already known. Two CSBM samples, one with high solubility (HS) (KOHPS - 80-85%) and another with low solubility (LS) (KOHPS - 50-55%) were used as reference samples. After a preliminary protocol with the HS reference sample testing &gt; 80% solubility was developed, adjustments in the intensity of agitation were made with 4 CSBM samples of known in vivo LYS digestibility (88-960/o digestible LYS) to match their KOHPS values in the 80-85% solubility range. The resulting standardized protocol yielded 83.08% KOHPS for the HS CSBM reference sample (mean value of 72 test results) with repeatability standard deviation, 1.45%; repeatability relative standard deviation, 1.74%; (Within-Lab) reproducibility standard deviation, 3.91%; and (\A/ithin-Lab) reproducibility relative standard deviation, 4.70%. lt also yielded 52.77% KOHPS for the LS CSBM reference sample (mean value of 71 test results) with repeatability standard deviation, 1.20%; repeatability relative standard deviation, 2.27%; (Within-Lab) reproducibility standard deviation, 5.32%; and (\Mthin-Lab) reproducibility relative standard deviation, 10.08%. ln conclusion, a standardized protocol is available for the determination of KOHPS of CSBM that will allow the building of regression equations for the estimation of AAD to be used in least-cost formulation.</div>
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		<strong>Precise nutrition: Regression equations using KOH protein solubility to estimate digestible lysine and digestible arginine in commercial lots of soybean meal that have undergone the Maillard reaction</strong></p>
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		<strong>Abstract</strong></p>
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		The objective of this study was to deliver a set of statistically significant regression equations (RE) for lysine (LYS) &amp; arginine (ARG) that will allow poultry nutritionists &amp; formulators to estimate the amino acid digestibility (AAD) of these amino acids (AAs) using a newly standardized protocol for the KOH protein solubility (KOHPS) test applied to commercial lots of soybean meal (CSBM). A total of 88 samples from a set of 100 previously analyzed for in vivo AAD and kept in frozen storage were analyzed for KOHPS. KOHPS values ranged from 86% to 13 % while digestible LYS (DLYS) coefficients (COEFF) ranged from 0.96 to 0.47. Digestible ARG (DARG) COEFF ranged from 0.97 to 0.62. Because it became evident from the total LYS &amp; total ARG analyses of the original samples that a net destruction of LYS &amp; ARG occurred as KOHPS dropped. Therefore, previously published RE for total AAs regressed on protein content were used to calculate destruction-corrected LYS &amp; ARG contents. Regressions of digestible COEFF on KOHPS were then run with &amp; without corrected digestible COEFF for both AAs. Linear regression provided the best fit for KOHPS vs. corrected digestible COEFF for both LYS &amp; ARG. One-slope broken line regression for LYS indicated that convergence criterion was met at KOHPS=80% &amp; DLYS coefficient=0.88 meaning that an adequately processed CSBM lot by solvent extraction is optimum at a minimum of 80% KOHPS which in turn is correlated with a minimum in vivo DLYS of 0.88. Having a statistically significant RE between KOHPS &amp; DLYS COEFF for CSBM contributes to the realization of precision nutrition.</p>
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		The data confirmed a long time observation that ARG is more digestible than LYS in CSBM, therefore by setting the minimum of 80% KOHPS for CSBM without Maillard reaction damage (overprocessing) on the basis of DLYS both AAs are at high AAD provided trypsin inhibitors are not in excess (underprocessing). ln conclusion, the RE here reported are the following:</p>
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		DLYS (coefficient*100) = 0.59 * KOHPS + 41.06 (N=76; R-square=0.95; r=0.97; P &lt;0.0001)</p>
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		DARG (coefficient*100) = 0.36*KOHPS + 62.33 (lrl=76; R-square=0.87; r=0.93; P &lt; 0.0001)</p>
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		NOTE: the utilization of these RE implies that the KOHPS values for CSBM have been generated using the newly standardized protocol.</p>
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