Biochemical studies on the live feed polychaete, <i>Nereis</i> sp., in relation to maturity stages

Abstract

Biochemical composition (protein, lipids, carbohydrates and moisture content) and fatty acid profile of the <i>Nereis</i> sp. was analyzed on dry weight basis in relation to maturity stages. Hatchery bred polychaetes (<i>Nereis</i> sp.) were procured and segregated into four size groups based on the oocyte diameter as immature (4.0 - 9.0 cm), early maturing (9.1-13.0 cm), late maturing (13.1-16.0 cm) and matured (16.0 cm and above). With the increase in maturity stages/size groups, the oocyte diameter was found to increase in size with a minimum of 9.48 µm (immature) to a maximum of 325.82 µm (matured). The amount of protein was found to be maximum (74.47±1.08%) in immature group and minimum (49.3±0.85%) in matured. Percentage of lipid gradually increased from immature to late maturing group but in matured group it was considerably reduced. Carbohydrate composition was almost same in all the groups ranging from 2.16±0.07 to 2.12±0.06%. Interestingly, fatty acid profile of <i>Nereis</i> sp. revealed significant differences among the various size groups. MUFA (monounsaturated fatty acid) was the most abundant fatty acid constituting about 47% to 53% of the total fatty acid. Saturated fatty acid (SFA) content was found to be increased with the increase in size group. Among PUFAs (polyunsaturated fatty acid), arachidonic acid was the most dominant fatty acid and with the increase in maturity the concentration of PUFA declined abruptly. Present study led to an understanding of why polychaetes and especially <i>Nereis </i> sp. is one of the most important food sources in aquaculture sector worldwide.