BIOCHEMICAL-COMPOSITION OF GONAD AND MUSCLE IN THE CATARINA SCALLOP, ARGOPECTEN VENTRICOSUS, AFTER REPRODUCTIVE CONDITIONING UNDER 2 FEEDING SYSTEMS

Favorable nutrition of scallops during reproductive conditioning in ha tcheries can be related not only to qualitative and quantitative aspec ts of diets, but also to the way in which food is supplied. The aim of the present study was to investigate whether continuous rather than d iscontinuous feeding could improve reproductive performance of Argopec ten ventricosus. For this purpose, the influence of two feeding system s (continuous and discontinuous) on gonadosomatic and condition index, and biochemical composition were analyzed in two experiments. In Expe riment 1, scallops were induced to spawn and a sample sacrificed after seven days of conditioning. Continuously fed (C-1) spawned scallops s howed lower gonadosomatic index (GSI) and a higher dry weight of spawn ed eggs, compared to discontinuously fed (D-1) scallops. The remaining scallops derived from both feeding systems (C-1 and D-1) during Exper iment 1 were conditioned for rematuration under both continuous (C-2) or discontinuous (D-2) feeding during Experiment 2, obtaining in this way a total of four groups: C1C2, D1C2, C1D2, D1D2. Continuous feeding during this experiment yielded higher GSI, accompanied by increased c oncentrations of acylglycerol (AG) and cholesterol (CHL) in the groups C1C2 and D1C2. This result indicated that feeding condition during th e first experiment did not detract from the positive response to conti nuous feeding during the second experiment. The C1D2 group had interme diate values of GSI and AG, and CHL levels equal to those of C1C2 and D1C2 groups, suggesting that better nutrition during the first experim ent partially compensated for inadequate nutrition during the second e xperiment. No significant differences were obtained for other variable s such as gonad proteins, muscle condition index, and adductor muscle levels of AG, CHL, proteins, and glycogen. Continuous feeding during c onditioning of A. ventricosus thus resulted in a better spawning capac ity and increased rematuration ability than discontinuous feeding. (C) 1998 Elsevier Science B.V. All rights reserved.