Effect of the partial substitution of fish meal by soybean meal with or without mannanoligosaccharide on the growth and feed utilization of sharpsnout seabream, Diplodus puntazzo (Cetti, 1777): preliminary results.

The present study was carried out in order to investigate the effects of the mannano- ligosaccharide (MOS) and fructooligosaccha- ride (FOS) on sharpsnout seabream, Diplodus puntazzo in the context of partial fish meal substitution by soybean meal. One-hundred- forty-four sharpsnout seabream of about 100 g initial body weight were randomly divided in 12 experimental tanks (180 litre each). Testing conditions included 12 fish per tank, with trip- licate tanks for treatment. The experimental period lasted 114 days. Average water temper- ature was 21.9±1.6°C, salinity was 30.0‰ and pH ranged from 7 to 8. Four isonitrogenous- isolipidic diets were tested: a control diet (FM) with fish meal as the sole protein source; a second diet (SBM) with approximately 40% of the protein supplied by soybean meal. The remaining two diets were formulated adding 8 g of MOS and FOS per kg of the SBM diet respectively. Average final weight, specific growth rate, feed conversion ratio and protein efficiency ratio remained unaffected by partial fish meal substitution and by MOS or FOS sup- plementation. Also apparent digestibility coef- ficients values for organic matter, protein, lipid and energy were not significantly affected by dietary treatment.