Evaluation of practical diets with various levels of dietary protein and animal protein for pond-raised channel catfish Ictalurus punctatus

Three levels of dietary protein (26, 28, or 32%) and four levels of animal protein (0, 2, 4, or 6%) were evaluated in a factorial experiment for pond-raised channel catfish using practical-type extruded feeds. Meat, bone, and blood meal (65% protein) was used as the animal protein source. Channel catfish fingerlings (average weight: 69 g/fish) were stocked into 48 0.04-ha ponds at a rate of 24,700 fish/ha. Four ponds were used for each dietary treatment. Fish were fed once daily to apparent satiation for 158 d. No differences were observed in weight gain, feed consumption, feed conversion ratio, survival, and hematocrits of channel catfish fed diets containing various levels of dietary protein and animal protein. Inclusion of animal protein in the diet did not affect fish dressout, percentage visceral fat, or fillet composition. Comparison of means pooled by dietary protein without regard to animal protein showed that fish fed diets containing 26% protein had a Lower percentage dressout than fish fed higher protein diets (55.4% vs. 56.3%). Fish fed the 32% protein diet had lower visceral fat than those fed the 26% or 28% protein diet (2.9% vs. 3.6% or 3.4%). Fillet fat was lower for fish fed the 32% protein diet than for fish fed the 26% protein diet (5.8% vs. 7.1%). Fillet fat in fish fed the 28% protein diet (6.5%) was not different from fish fed either 26% or 32% dietary protein. No differences were detected in fillet protein, moisture, and ash concentrations among fish fed diets containing various concentrations of protein. There were no interactions between dietary protein and animal protein for any variables. Results from the present study indicate that animal protein can be eliminated from diets for grow out of channel catfish fed to apparent satiation using diets containing 26% to 32% crude protein.