Effect of Treating Full-Fat Whole Soybeans with Dry Heat or Formaldehyde on Digestibilities of Nitrogen and Polyenoic Acids

Abstract

Full-fat whole soybeans were treated with dry heat (100 to 200 C for 4 or 8 h) or formaldehyde (0 to 8 g/100 g soybean protein). Heating at 140 C for 4 h reduced nitrogen degradability in an artificial rumen by 84% but reduced in vivo digestibility by only 5%. Correlation coefficient between in vivo and acid-pepsin (.01%) nitrogen digestibilities was .95. Formaldehyde treatment at 3.5 g per 100 g soybean protein reduced nitrogen degradability in an artificial rumen by 90% but reduced nitrogen digestibility in acid-pepsin (.01%) by only 6%. None of the treatments was effective (<31%) in protecting soybeans’ polyenoic acids from hydrogenation by rumen bacteria. © 1978, American Dairy Science Association. All rights reserved.