Use of defatted fermented rice bran in the diet of juvenile mullets Mugil liza

Abstract

The study aimed to evaluate the use of increasing levels of defatted rice bran fermented by Rhizopus oryzae in the diets of juveniles of mullet fish Mugil liza, assessing growth parameters, proximal carcass composition, and lipid peroxidation (TBARS) in the liver and intestine. Six experimental diets were formulated: a control treatment without rice bran, a second treatment with the inclusion of 200 g kg−1 of defatted rice bran without fermentation (DRB200), and the remaining treatments received diets with the inclusion of 100, 200, 300, or 400 g kg−1 of fermented bran. The experimental design used 216 mullet juveniles (2.10 ± 0.04 g) randomly distributed in a recirculation system composed of 18 tanks, divided into six treatments and three replications, with 12 fish per experimental unit. During the experiment, fish were fed ad libitum three times a day, for 50 days. No mortalities were recorded during the experimentation. The performance variables showed that an inclusion equal or higher than 200 g kg−1 of fermented rice bran resulted in decreased growth. Furthermore, in carcass proximal composition, the lipid content decreased with higher inclusion levels of fermented rice bran and the control treatment showed the highest lipid content, while the ash content of fish carcasses increased with the higher inclusion of the tested ingredient. No differences were recorded for TBARS in the liver and intestine. According to the results, we recommend a maximum inclusion of 100 g kg−1 fermented rice bran in diets for M. liza juveniles.