Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 8, 2002
Publication Date: July 30, 2002
Citation: Lim, C.E., Peres, H., Klesius, P.H. 2002. Nutritional value of heat-treated soybean meal for channel catfish (Ictalurus punctatus). In: Book of Abstracts. 10th International Symposium on Nutrition and Feeding of Fish. June 2-7, 2002, Rhodes, Greece. p. 190. Technical Abstract: A study was undertaken to evaluate the effect of heat treatment of defatted raw soybean meal (RSBM) on the growth, hematology, immune response and resistance of channel catfish to Edwardsiella ictaluri. Six isocaloric and isonitrogenous practical diets were formulated. A diet containing 45% of commercial soybean meal (CSBM) served as the control. RSBM, unheated (RSBM0) and heated in an autoclave (dry cycle) at 130 deg.C and 22 psi for 5 (RSBM5), 10 (RSBM10), 20 (RSBM20), and 40 min (RSBM40), was used to isonitrogenously replace the CSBM in the control diet. Each diet was fed to juvenile catfish (4.98g) in triplicate aquaria twice daily to satiation for 10 weeks. Another batch of diets containing 1% of chromic oxide was used for digestibility trial. Heating RSBM for 20 min. or longer lowered trypsin inhibitor (TI) content and increased the apparent protein digestibility. The protein dispersibility index decreased with increasing heating duration. Fish fed CSBM and RSBM40 diets had similar weight gain, protein efficiency ratio and apparent protein utilization which were significantly higher than those of fish fed the other diets. Feed intake significantly increased when RSBM was heated for 20min or longer. Fish fed the CSBM diet had significantly lower feed intake but higher feed efficiency than those fed the CSBM diet. Whole-body protein was highest for fish fed the RSBM40 diet but did not differ from that of fish fed the CSBM diet. Hepatosomatic and visceral indices of fish fed CSBM and RSBM40 diets were significantly lower than those fed other diets. Total cell count, red blood cell count, hematocrit and hemoglobin were not affected by dietary treatments. Plasma lysozyme activity and protein of fish fed the RSBM40 diets were similar and significantly higher than those of fish fed the other diets. Cumulative mortality 14-day post challenge with E. ictaluri was significantly lower for fish fed the RSBM5 and RSBM10 diets but significantly increased when heating time was increased to 40 min. Macrophage chemotaxis in the presence of exoantigen and antibody titer against E. ictaluri was higher for the groups fed the RSBM containing diets than those fed the CSBM diet, although the differences were not always significant.