Effects of Dietary Fiber Concentrations Supplied by Corn Bran on Feed Intake, Growth, and Feed Efficiency of Channel Catfish

The present study examined the effects of dietary fiber and digestible energy on the feed intake, growth, and feed efficiency of juvenile channel catfish Ictalurus punctatus. Fish with an initial weight of 9.8 ± 0.1 g/fish (mean ± SD) were stocked in 110‐L flow‐through aquariums and fed for 9 weeks with practical diets that contained graded levels of fiber supplied by corn bran. As total dietary fiber (TDF) increased, feed consumption and weight gain increased and then decreased, showing a quadratic response. Maximum feed consumption occurred at a TDF level of 27.0% (5.7% crude fiber, 19.1% neutral detergent fiber [NDF]). Channel catfish appear to have some ability to adapt to increased dietary fiber by increasing feed intake to satisfy their energy requirements. Maximum weight gain was achieved at a TDF level of 23.4% (5.0% crude fiber, 15.7% NDF), indicating that the presence of dietary fiber at certain levels is beneficial to the fish. The maximum tolerance level for TDF by channel catfish was estimated to be 32.1% (6.6% crude fiber, 24.9% NDF). Feed efficiency, hepatosomatic index, and body fat decreased linearly with increasing dietary fiber. The maximum fiber tolerance levels may be used as upper limits for fiber when formulating practical diets for catfish containing corn by‐products.