Submitted to: Annual Eastern Fish Health Workshop
Publication Type: Abstract Only
Publication Acceptance Date: February 18, 2004
Publication Date: March 22, 2004
Citation: EVANS, J.J., PASNIK, D.J., PERES, H., LIM, C.E., KLESIUS, P.H. ABSENCE OF INTESTINAL HISTOLOGIC CHANGES IN FINGERLING CHANNEL CATFISH (ICTALURUS PUNCTATUS) FED RAW SOYBEAN MEAL. ANNUAL EASTERN FISH HEALTH WORKSHOP. 2004. Technical Abstract: Considerable effort has been made to utilize alternative protein sources to replace fish meal. Soybean meal (SBM) is a commonly utilized plant protein in fish feeds, because it is readily available and inexpensive, and has a high nutritional value. However, the inclusion of high levels of SBM in fish diets has usually produced unfavorable effects, such as reduced growth rates, reduced feed utilization efficiency, and adverse intestinal histologic changes. Many of these negative effects were attributed to heat-labile anti-nutritional factors of SBM, and thus SBM is commonly heat-treated prior to use in fish feeds. The histopathologic effects of feeding heat-treated or non-heat-treated raw SBM to fingerling channel catfish (Ictalurus punctatus) had not been previously assessed, but were studied here. Fish were fed one of six diets: a diet containing 45% commercial soybean meal (CSBM), or diets with the CSBM replaced by non-heat-treated raw soybean meal (RSBM0), or RSBM heated in an autoclave at 130 °C and 22 PSI for 5 (RSBM5), 10 (RSBM10), 20 (RSBM20), and 40 (RSBM40) min. After 10 weeks, tissue samples were taken from the stomach, proximal intestine, distal intestine, liver, pancreas, and spleen from fish in each group for histologic examination. Mild necrotic lesions were found in the gastric glands, pancreas, and liver of fish in all the groups, including the control group. Hepatic glycogen deposition was also observed in all the groups, as was moderate hyperplasia of the bile ducts. Spleen samples exhibited considerable brown-black pigment deposition around the splenic corpuscles and diffuse mild-to-moderate congestion in all of the groups. Generally, these histologic effects appeared to be equivocal between all of the groups, and no abnormalities were noted in the proximal or distal intestines. These findings suggest that unheated 45% RSBM could be utilized in channel catfish feed without causing severe histologic changes routinely associated with SBM utilization in fish.