Comparison of practical diets with and without animal protein at various concentrations of dietary protein on performance of channel catfish Ictalurus punctatus raised in earthen ponds

摘要

A 2 X 5 factorial experiment was conducted using practical-type extruded feeds containing 20, 24, 28, 32 or 36% CP with or without animal protein. The animal protein supplement consisted of 4% menhaden fish meal and 4% meat, bone and blood meal. Channel catfish fingerlings, mean weight 26.3 g, were stocked into fifty 0.04-ha ponds at 24 700 fish/ha. Five ponds were used for each dietary treatment. Fish were fed once daily to satiation for 202 days. There were no differences in feed conversion ratio(FCR), percentage fillet moisture or survival among treatments. In fish fed on diets lacking animal protein, feed intake (FI), liveweight gain (LWG) and percentage dressout were lower for those fed on the 20% protein diet than those fed on diets containing 28 and 32% protein. Fish fed on 28, 32 or 36% protein diets without animal protein did not differ with respect to percentage dressout and percentage visceral fat; fish fed on the 36% protein diet had higher percentage fillet protein and a lower percentage fillet fat than fish fed on the other diets with the exception of fish fed on the 28% protein diet. In fish fed on diets containing animal protein, FI, LWG, percentage fillet protein and ash, and percentage dressout were lower and visceral fat washigher for fish fed on the 20% protein diet than those fed on the other diets. Fish fed on diets containing 24% protein and above with animal protein did not differ with respect to LWG and FI, but fish fed on the 24% protein diet had a higher percentagefillet fat than fish fed on the 32 or 36% protein diet. Fish fed on the 32% protein diet had lower visceral fat. Considering animal protein vs. non-animal protein with data pooled across all diets irrespective of dietary protein level, LWG and FCR of fish fed on diets containing animal protein were higher than those fed on diets containing no animal protein. However, LWG of fish fed on diets containing 20, 28 or 32% protein with or without animal protein did not differ. Dressout percentage and fillet protein were higher and fillet fat was lower for fish fed on diets containing no animal protein than those fed on diets containing animal protein. Data from this study indicated that animal protein may not be a necessary dietary ingredient for fish fed on28 or 32% protein diets, typically used for grow-out of pond-raised channel catfish under satiation feeding conditions. Whether animal protein should be included in catfish diets containing <28% protein is unclear, since fish fed on the 24% protein dietbenefited from it, but those fed on the 20% protein diet did not benefit from the animal protein.