Induced Non-Enzymatic Browning of Soybean Meal. III. Digestibility and Efficiency of Protein Utilization by Ruminants of Soybean Meal Treated with Xylose or Glucose

Trials were conducted to evaluate effects of non-enzymatic browning of soybean meal (SBM) on efficiency of protein utilization and N digestibility. In trial 1, 48 Suffolk-Finnsheep lambs (22 kg) were fed 80 d to evaluate efficiency of protein utilization for growth when supplemental protein was fed as urea (U), commercial SBM (CS), or commercial SBM (pH 8.5, 83% dry matter) containing xylose (3 mol/mol SBM-lysine) and heated 30 min (XTS-30) or 55 min (XTS-55). Diets containing graded levels of N from CS, XTS-30 and XTS-55 were fed. Response criterion was efficiency of protein utilization, plotted as gains of lambs fed test proteins minus gain of lambs fed U vs supplemental test protein fed. Efficiencies of protein utilization were .62, 1.27 and .91 for CS, XTS-30 and XTS-55, respectively. Protein from XTS-30 was used more efficiently (P<.05) than that from CS. In trial 2, apparent digestibility of N from CS (97%) was higher (P<.01) than XTS-30 (77%) and XTS-55 (82%) by Suffolk-Finnsheep lambs (27 kg). In trial 3, 60 mixed-breed steers (218 kg) were fed individually for 105 d to evaluate glucose as a reducing sugar. Glucose-treated SBM (GTS) was prepared by mixing glucose (3 mol/mol SBM lysine) with SBM, adjusting pH and dry matter content to 8.5 and 80%, respectively, and heating at 150 C for 60 min. Supplemental N sources were U, CS, GTS and a 50:50 mixture (protein basis) of corn gluten meal and blood meal (CGM/BM). Efficiencies of protein utilization were .90, 1.91 and 1.85 for CS, GTS and CGM/BM, respectively. Efficiency of protein utilization of GTS was higher (P<.05) than CS but not different (P>.10) from CGM/BM. In trial 4, apparent digestibility of N from CS (100%) was higher (P<.05) than GTS (93%) by Suffolk-Finnsheep lambs (40 kg). These results are interpreted to indicate that controlled, non-enzymatic browning improved efficiency of soybean protein utilization by ruminants.