Strategies for utilizing overprocessed soybean meal: I. Amino acid supplementation, choline content, and metabolizable energy

The overheating of soybean meal (SBM) is known to reduce its nutritional quality by damaging one or more amino acids. Three studies were conducted to evaluate the effects of lysine, methionine, and threonine supplementation on the performance of broiler chicks fed severely overprocessed SBM as determined by protein solubility (PS) in 0.2% KOH. Feeding heat-damaged SBM (PS 35%) sharply reduced 15-day body weight and increased feed:gain ratio. However, the addition of 0.3% lysine largely overcame the effects of feeding overprocessed SBM. Methionine and threonine alone, in combination, or in addition to lysine had no statistically significant effect. Overprocessed of SBM did not affect its choline content. The AMN(n) of extremely heat-damaged SBM (PS 39%) was significantly reduced, but this effect was not seen in moderately overprocessed SBM (greater than or equal to 53% PS).