Nutritional evaluation of canola meal as fish meal replacement for juvenile spotted rose snapper (Lutjanus guttatus): Effects on growth performance, hematological parameters, body composition, and nutrient digestibility

Abstract This study examined the nutritional value of solvent-extracted canola meal (CM) as a replacement for fish meal (FM) in practical diets for spotted rose snapper (Lutjanus guttatus). Four isonitrogenous (490 g/kg crude protein), isoenergetic (19.03 kJ/g) diets containing 0 g/kg (CM0), 150 g/kg (CM150), 300 g/kg (CM300), or 450 g/kg (CM450) of CM protein instead of FM protein were used. All CM diets were supplemented with phytase and protease enzymes; DL-methionine was supplemented to the CM450 diet. Each diet was fed to triplicate groups of 15 fish (average body weight 36.2 ± 0.03 g) per tank to apparent satiation three times a day for 70 days. A one-way ANOVA showed that the specific growth rate (SGR) was significantly lower when CM inclusion was 26.67% or higher, replacing 450 g/kg of fish meal protein or more. There was a significant negative relationship between growth response and the level of FM protein replacement. Survival and dry feed intake (DFI) were unaffected by fish meal replacement. The protein efficiency ratio (PER) was highest at the lowest CM inclusion level. Hematological parameters, including hematocrit, protein, hemoglobin, triglycerides, and cholesterol, did not vary between treatments. Juvenile fish fed the 450 g/kg CM diet showed the lowest protein content. The apparent digestibility coefficient (ADC) of dry matter and energy were significantly reduced by CM addition. Our results show that CM can be a suitable alternative protein source for spotted rose snapper juveniles heavier than 37 g. Under the experimental conditions tested in this study, up to 300 g/kg FM protein can be replaced by CM protein with no significant adverse effects on growth, feed utilization, hematological parameters, or body composition in this species.