Utilization of Soybean Meal as a Protein Source in a Newly Developed Soft-dry Pellet for Yellowtail.

Abstract

The availability of defatted soybean meal (SBM) as a substitute for fish meal in a newly developed soft-dry pellet (SDP) was evaluated in juvenile (160g on average) and adult (1,200g on average) yellowtail by feeding SDP containing 0-30% SBM for 74 and 143 days, respectively. Palatability and acceptability in both sizes of fish were not affected by the inclusion of SBM in SDP, while growth and feed gain ratio were slightly reduced at higher SBM levels, probably due to the nitrogenous and caloric imbalance of the diets. There were no marked differences in proximate composition and rheological properties of muscle together with hemochemical parameters in either juvenile or adult yellowtail fed on SDP containing 0-30% SBM. Digestibility of crude protein in the experimental SDP and SBM was about 85% regardless of dietary SBM levels, while that of crude starch was reduced by the elevation of dietary SBM levels. The results of the present study have shown that SBM can be included in the SDP up to 30% as a substitute for fish meal, although elevation of a protein or energy level will be required to obtain feed performances comparable to a fish meal diet.