The effect of different feeding rates on growth, feed efficiency and immunity of juvenile Penaeus monodon

Abstract

Juvenile Penaeus monodon weighing about 1.46 g were fed on a diet for 8 weeks at various daily feeding rates of 3, 4, 5, 6, 7, 8 and 9 % of their body weight (BW), and the growth, feed utilization, blood parameters and non-specific immunity were determined. Forty shrimp per tank were distributed into 28 500-L fiberglass tanks, and they were fed four times 1 day. After the 56-day trial, survival was over 90 % and was not significantly affected by feeding rates. Final weight, weight gain and specific growth rates gradually increased with increasing feeding rate up to 8 % and then kept constant. Feed conversion rate (FCR: 1.08–2.20) from 9 % feeding rate treatment was significantly higher than that from 3 to 7 % feeding rate treatments (P < 0.05) but without difference to 8 % feeding rate treatment. Protein efficiency ratio linearly decreased with the increase in feeding rate. The apparent digestibility coefficients for dry matter, protein (APD) and energy (AED) of 3 % and 4 % feeding rate treatments were significantly lower than that of 5–9 % feeding rate treatments (P < 0.05). Activities of plasma glutamic oxaloacetic transaminase and glutamic pyruvic transaminase and concentrations of plasma cholesterol, triacylglycerol and low-density lipoprotein were increased with increasing feeding rate. Superoxide dismutase activities in hepatopancreas of shrimp from 3 to 5 % feeding rate treatments were significantly higher than that of shrimp from 7 to 9 % feeding rate treatments (P < 0.05) but without significant difference with 6 % feeding rate treatment. Nonlinear regression analysis of SGR indicated that the optimum feeding rate of juvenile P. monodon is 7.5 % BW/day.