Researchers evaluated the efficacy of eight sources of soybean meal (SBM) which included six new non-genetically modified soya varieties in practical feed formulation for Pacific white shrimp, Litopenaeus vannamei, using both growth and digestibility trials. A soybean meal-based reference diet was formulated using conventional soybean meal, which was then replaced on an isonitrogenous basis with various other experimental soybean meals.
In a 6-week growth trial, shrimp in four replicate tanks per dietary treatment (10 shrimp per tank, initial weight 0.52 ± 0.04 g) were cultured in a recirculating system. There were no significant differences with respect to per cent weight gain and survival across all dietary treatments. Apparent digestibility coefficients for the eight different soybean meals were determined for dry matter, gross energy and crude protein using chromic oxide as a inert marker. Coefficients ranged from 71.3% to 88.3%, from 76.6% to 91.3% and from 93.6% to 99.8%, for dry matter, gross energy and crude protein, respectively. Improved digestibility values were observed in the SBM which was characterized by crude protein (471 g/kg), crude fat (97 g /kg), low cooking temperature (180 °C), high nitrogen solubility index (689 g/kg) and a protein dispersibility index (619 g/kg). The researchers concluded that this study demonstrates that new lines of soybean meal can be used to improve digestibility coefficients in shrimp feeds.