The effect of dry heat processing of full fat soybean on trypsin inhibitor activity, urease activity, protein solubility in KOH and broilers performance

An experiment was conducted to evaluate the effect of dry heat processing of full fat soybean for different times on nutrient quality, probably heat damaging of soybean and performance of broiler chicks. The full fat soybeans were heated in oven at 150°C for 0, 20, 40 and 60 minutes and was added to the basal diet in two graded levels (20.4 and 46.67%). The experiment was done as a completely randomized design in a factorial arrangement with 4 replicate in each treatment. The experimental diets were compared with a control diet which contained soybean meal instead of full fat soybean. Urease and trypsin inhibitor activity were measured as an indicator for effectiveness of heat processing of soybean. Protein solubility in potassium hydroxide was measured for determining the probably heat damaging of soybean. The result of this experiment showed that heat processing for 60 minutes has greatest effect in reducing the urease and trypsin inhibitor activity but does not affect the protein solubility and thus reducing the protein quality. Finally, the effect of diets containing processed soybeans on male broiler performance from 21 to 42 days was evaluated and was observed that the effects of heat processing time and the use of soybean seed in the diet on chick performance was significant (P<0.05). Heat processing for 60 minutes showed the highest weight gain and feed intake, lowest feed conversion ratio and pancreases hypertrophy and the performance of broiler in this experiment was closed to the control diet (P>0.05). The consumption level of 20.4% soy in the diet compared with 46.67% showed better performance in parameters. Interaction effects between inclusion of soybean in diet and soy processing time was significant (P<0.05). Dry heat proccessing of full fat soybean for 60 minute and add it to the basal diet at a level of 20.4% yielded the best performance in broiler chickens.