GROWTH AND BODY-COMPOSITION OF CHANNEL CATFISH (ICTALURUS-PUNCTATUS) FED DIETS CONTAINING VARIOUS PERCENTAGES OF CANOLA-MEAL

A 12-week feeding trial was conducted in aquaria with juvenile (10 g) channel catfish to examine the effects of partially substituting canol a meal for soybean meal in prepared diets. Six isonitrogenous (32% pro tein) and isocaloric (2.7 kcal digestible energy g(-1)) diets were for mulated to contain 0, 12, 24, 36, and 48% canola meal (CM). There were two diets with 0% CM; one with 8% fish meal (FM) and one with 4% FM. All diets with CM had 4% FM. Fish were fed twice daily all they could consume in 20 min. After 12 weeks, fish fed a diet with 8% FM and 0% C M had significantly higher (P < 0.05) percentage weight gains than fis h fed all other diets, Fish fed diets containing 12 and 36% CM had sig nificantly higher (P < 0.05) percentage weight gains (average 604%) th an fish fed a diet containing 48% CM. Feed conversion ratio (FCR) of f ish fed a diet containing 48% CM was significantly (P less than or equ al to 0.05) higher (2.25) than values for fish fed 12, 24, and 36% CM. There were no histological differences in the thyroid of fish fed any of the diets, These data suggest that channel catfish can be fed diet s containing up to 36% CM without adverse effects on growth or body co mposition. Fish fed a diet with 48% CM had a lower percentage weight g ain compared with fish fed diets containing between 12 and 36% CM, pos sibly due to reduced palatability of the diet, Use of canola meal in p ractical diets for channel catfish may allow producers and feed mills to formulate more economical diets by adding another plant protein sou rce to ingredients used in commercial catfish diets. (C) 1997 Elsevier Science B.V.