Dietary lycopene supplementation on Nile Tilapia (Oreochromis niloticus) juveniles submitted to confinement: effects on cortisol level and antioxidant response

This study evaluates the inclusion of lycopene in the commercial diet for Nile Tilapia exposured to a stressor. For 60 days, fish diet was supplemented with lycopene (600 mg kg^?1 diet) and at the end, subjected to confinement for 90 min. Zootechnical parameters (weight gain, specific growth rate and intake), hormonal (cortisol level), biochemical {enzyme activity and lipid peroxidation level thiobarbituric acid (TBARS)]} and physical (instrumental colour) parameters were also evaluated. Supplementation with lycopene did not alter zootechnical parameters. In unconfined fish, catalase (CAT) activity was reduced in the white muscle of fish fed with lycopene; however, in red muscle, it was not altered. In fish under confinement, plasma cortisol increased as well as CAT, glutathione reductase (GR) and lactate dehydrogenase (LDH) activity in both muscles. Lipid peroxidation of the fillet also displayed higher values. However, the lycopene supplementation abolished the effects of confinement available through cortisol levels, remaining unchanged in the above parameters, activity of CAT, GR and LDH in both muscles and TBARS content of the fillet; in addition, it did not induce alteration of fillet coloration. Inclusion of lycopene in commercial feed reduces the impact of confinement and does not alter the zootechnical parameters; additionally, no modification of the fillet colour from juvenile Nile tilapia was observed.