Substitution of soybean meal and oil for fish meal in practical diets fed to channel catfish, Ictalurus punctatus (Rafinesque): effects on body composition

Three isonitrogenous and isocaloric rations containing various levels of commercially dehulled soybean meal as replacement for menhaden fish meal were fed to four replicate groups of channel catfish, Ictalurus punctatus (Rafinesque), fingerlings, mean initial live weight 13. 7 g, in 0.4‐ha earthen ponds for 114 days. As fish meal was removed from the experimental diets, vegetable fat, soybean meal, and inorganic phosphorus were increased to maintain 35% crude protein, 11. 7 Mj of digestible energy (DE) per kg, and a minimum of 0.45% available phosphorus. The percentage of the whole body weight made up of dressed carcass, head, skin and viscera did not vary significantly among dietary treatments. Average values for dressed carcass, head, skin and viscera were 60.8%, 20.8%, 6.7% and 9.7%, respectively. The chemical composition of the various body parts was not significantly affected by diet. Average fat percentages for dressed carcass, head, skin, and viscera were 8.2%, 7.3%, 16.0% and 26.4%, respectively. Average protein percentage were 15.7%, 14.9%, 22.2% and 11.4%, respectively. These results indicate that varying the percentage of fat added to a practical catfish diet from 0% to 3.8%, but holding the DE constant, will not affect dressing percentage or body composition of the fed fish.