Book reviews

Abstract

The inclusion of feeding effectors in plant-based diets is a strategy to accelerate feed detection and consumption by shrimp. This study evaluated the effect of krill meal (KM), krill oil (KO) and fish hydrolysate (FH) addition to a soybean-based diet on feeding behavior and growth of Litopenaeus vannamei. Ten diets (360 g/kg crude protein) were formulated including FH, KM and KO at 0, 10, 20 and 40 g/kg levels named as: Basal (0); FH10 (10 g/kg fish hydrolysate), FH20 (20 g/kg fish hydrolysate), FH40 (40 g/kg fish hydrolysate); KM1 (10 g/kg krill meal), KM20 (20 g/kg krill meal), KM40 (40 g/kg krill meal); KO10 (10 g/kg krill oil), KO20 (20 g/kg krill oil) and KO40 (40 g/kg krill oil). A growth trial was performed using twenty shrimp (0.15 ± 0.01 g) stocked per 100 L glass aquaria (four replicates/diet) in an indoor clear water recirculation system (4.2 ppt, 28 °C). Animals were fed the experimental diets four times a day for six weeks. At the end of the trial all animals were counted and weighted. Following, 300 animals (3.93 ± 0.35 g) were aleatory selected and transferred back to the system (10 shrimp/aquaria). Three replicates were used per treatment (ten diets) for feed intake and acoustic feeding behavior analysis. The food consumption and feeding activity sounds were recorded simultaneously in 30 min intervals during five consecutive days. All feeding effectors at the inclusion levels tested significantly increased L. vannamei food consumption and the passive acoustic monitoring indicated that shrimp ate faster and for longer periods of time. Food consumption was significantly higher in the treatments KM20, KM40 and KO40. The addition of feeding effectors also enhanced shrimp growth performance and significantly better values of biomass, final weight, and food conversion ratio were observed in the treatment KM40. Weight gain (%) was significantly improved only in shrimp offered KM40, KO20 and KO40 diets. It is concluded that KM, KO and FH can stimulate food consumption of soy-based diet by L. vannamei from 10 g/kg addition while the amount of food consumed and growth has been shown to be in general dose-related, although in a different way, for each type of feeding effector.