Substitution of canola meal for soybean meal in diets for channel catfish Ictalurus punctatus.

摘要

Rapeseed meal was used in channel catfish, I. punctatus, diets at levels of 0, 15.4, 30.8, 46.2 and 61.6%, by progressively replacing (on an equal N basis) 0, 25, 50, 75 or 100% of solvent-extracted soyabean meal in the control diet. The diets wereformulated to contain 29% CP and 2650 kcal DE/kg on an air-dry basis. Each diet was fed to juvenile channel catfish to satiation twice daily for 10 weeks. Fish fed on the diets containing the 2 lowest levels of rapeseed meal (15.4 and 30.8%) had similarweight gains, feed intakes, feed utilization efficiencies, and percentage survivals relative to the group fed on the control diet. Weight gains and feed intakes declined significantly as the dietary levels of rapeseed meal were increased to 46.2% or higher, probably because of reductions in diet palatability and some impairment of feed utilization due to the presence of increased levels of antinutritional factors, particularly glucosinolates. Whole body percentages for moisture and CP were unaffected bydietary treatments. Body ash content, however, was lowest for fish fed on the control diets but was essentially the same in fish fed on the other diets. Fish fed on the diet containing 30.8% rapeseed meal had the lowest body fat content, though this effect is not thought to be diet-related. Values for red blood cell concentration, haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration were not affected by dietary rapeseed meal level, but haematocrit was higher (though not always significant) in fish fed on the control diet. The results suggest that rapeseed meal can comprise 31% of the diet of channel catfish by replacing half of the amount of soyabean meal used in the control diet without adversely affecting growth or any other aspect of performance.