Addition of essential oil from lemongrass to the tambaqui ( Colossoma macropomum ) diet: Effects on growth, intestinal enzymes, haematological and metabolic variables, and antimicrobial challenge

Abstract

This study evaluated the effect of dietary addition of essential oil from lemongrass (Cymbopogon citratus) (EOCC) on growth, intestinal enzymes, biochemical and haematological variables, and survival after Aeromonas hydrophila infection in tambaqui (Colossoma macropomum) juveniles. Five diets with different levels of EOCC-0.0 (control), 0.25, 0.50, 1.00 and 1.50 ml kg diet −1 -were evaluated for 60 days, followed by 15 days of bacterial infection. The major chemical compound of EOCC was α-citral (73.55%). There were no differences in fish survival. Supplementation of 0.25 or 0.50 ml EOCC kg diet −1 increased weight gain (p = 0.034). In general, haematological variables were increased in the treatment 0.25 ml EOCC kg diet −1 (p < 0.05). As the EOCC concentration in the diet increased, plasma glucose, albumin, total cholesterol levels and hepatic somatic index were decreased, and plasma total proteins and muscle glycogen levels were increased (p < 0.05). In tambaqui fed 0.50 ml EOCC kg diet −1 , there were increased hepatic glycogen levels (p < 0.016) and intestinal alkaline protease activity (p = 0.049). In conclusion, up to 0.50 ml EOCC kg diet −1 could improve growth performance, haematological variables, muscle glycogen levels and intestinal alkaline protease activity in tambaqui but did not affect fish survival after A. hydrophila infection.