Optimal dietary lipid level for large yellow croaker (Pseudosciaena crocea) larvae

Abstract

A 30-day feeding experiment was conducted in blue tanks (70 × 50 × 60 cm, water volume 180 L) to determine the effects of dietary lipid levels on the survival, growth and body composition of large yellow croaker (Pseudosciaena crocea) larvae (12 days after hatchery, with initial average weight 1.93 ± 0.11 mg). Five practical microdiets, containing 83 g kg−1 (Diet 1), 126 g kg−1 (Diet 2), 164 g kg−1 (Diet 3), 204 g kg−1 (Diet 4) and 248 g kg−1 lipid (Diet 5), were formulated. Live feeds (Artemia sinicia nauplii and live copepods) were used as the control diet (Diet 6). Each diet was randomly assigned to triplicate groups of tanks, and each tank was stocked with 3500 larvae. During the experiment, water temperature was maintained at 23(±1) °C, pH 8.0 (±0.2) and salinity 25 (±2) g L−1. The results showed that dietary lipid significantly influenced the survival and growth of large yellow croaker larvae. Survival increased with the increase of dietary lipid from 83 to 164 g kg−1, and then decreased. The survival of larvae fed the diet with 83 g kg−1 lipid (16.1%) was significantly lower than that of larvae fed other diets. However, the survival in larvae fed the diet with 16.4 g kg−1 lipid was the highest compared with other artificial microdiets. Specific growth rate (SGR) significantly increased with increasing dietary lipid level from 83 to 164 g kg−1 (P < 0.05), and then decreased. The SGR in larvae fed the diet with 164 g kg−1 lipid (10.0% per day) was comparable with 204 g kg−1 lipid (9.6% per day), but were significantly higher than other microdiets (P < 0.05). On the basis of survival and SGR, the optimum dietary lipid level was estimated to be 172 and 177 g kg−1 of diet using second-order polynomial regression analysis respectively.