Effect of dietary ascorbate fortification on lipolysis activity of juvenile black sea bream Acanthopagrus schlegeli

ABSTRACT:   Hatchery-reared black sea bream Acanthopagrus schlegeli juveniles averaging 0.05 g in body weight were fed either a control diet (commercial diet) or an experimental diet in which the commercial diet was fortified with 50 mg l -ascorbyl 2-monophosphate Mg (APM)/100 g diet for 50 days. Calcium ascorbate supplemented as a vitamin mixture in the control diet was completely destroyed during storage. Fortification with APM significantly increased the ascorbic acid levels in the muscle, liver, brain and eye. Although APM fortification did not influence growth, survival or fish body composition, adipocyte diameter in the intraperitoneal fat body (IPF) was significantly reduced. After the feeding experiment, the fish were kept for 39 days without feeding. Fortification with APM resulted in high survival, high muscle protein retention and low body weight loss. The results suggested the necessity of fortification with an adequate amount of ascorbate in the diet. While fatty acid compositions of the IPF, muscle and liver were not significantly influenced by APM fortification, characteristic changes in the fatty acid profile were found after starvation. Vitamin C and highly unsaturated fatty acids seemed crossly interactive in relation to lipolysis activity in black sea bream juveniles.