Replacement of fish meal by a novel non-GM variety of soybean meal in cobia, Rachycentron canadum: Ingredient nutrient digestibility and growth performance

•Effects of fish meal replacement on Cobia diets were examined.•Navita's ADCs were higher than those of SBM for nearly every nutrient evaluated.•Crude protein ADCs were 82 and 69% for Navita and SBM, respectively.•Fish fed the Navita-high diet had the lowest FIFO ratio at 0.9 ± 0.16.•Results indicate that Navita meal can be incorporated at very high levels in cobia.

A constraint for the expansion of cobia aquaculture is the availability of high quality formulated diets which reduce or eliminate fish meal (FM) protein. Therefore, the nutritive value of a novel soybean cultivar, Navita™ (Navita, non-genetically modified and selectively bred soy), and regular, commodity soybean meal (SBM, de-hulled, defatted, roasted and solvent-extracted) was evaluated for cobia, Rachycentron canadum via separate digestibility and growth trials. In the first experiment Navita's apparent digestibility coefficients (ADC) were higher than those of SBM for nearly every nutrient evaluated. Crude protein ADCs were 82 and 69% for Navita and SBM, respectively. Apparent DC for amino acids ranged from 68 to 109% for Navita whereas, amino acid ADCs for SBM varied from 42 to 98%. The feeding trial utilized fish of a size that more closely resembles commercial cobia stocking (1.8 kg), and was conducted over a 91-day period. Experimental diets (iso-nitrogenous and iso-energetic) were formulated such that 67% of the FM protein in the reference diet was replaced by either a combination of SBM + soy protein concentrate (SPC, Solae Profine®) labeled MXSB-diet, or by a combination of SPC + Navita; Navita-diet, hereafter. A fourth experimental diet had 80% of the FM protein replaced by a combination of Navita + SPC and was identified as Navita-high. No significant differences (P > 0.05) were observed in fish fed the experimental diets for feed conversion ratio, protein efficiency ratio, feed efficiency, mean daily intake, gross protein intake, gross energy intake, visceral somatic index, muscle ratio, and hepatosomatic index. Fish fed the Navita-high diet had the lowest fish in:fish out ratio (FIFO) at 0.9 ± 0.16. These results indicate that Navita meal can be incorporated at very high levels in the diet of marine carnivorous fish such as cobia with no detriment to performance, making it a prime candidate for FM replacement in aquafeeds.