Clove essential oil decreases antemortem stress and acts as an antioxidant in Nile tilapia

Abstract

This study investigated the effect of clove essential oil used prior to stunning by cranial percussion and hypothermia on Nile tilapia (Oreochromis niloticus) welfare and fillet quality. A total of 100 tilapias were divided into four groups in a 2 × 2 factorial design, exploring two stunning methods with and without clove essential oil. Behavioral responses, glucose, lactate, pH, water holding capacity, color parameters, lipid and protein oxidation, and oxidative stress were analyzed. The application of clove essential oil resulted in 100% numbing in swimming and stimulus response behaviors, and 96% in balance and eye vestibule reflex variables. Significant reductions in glucose (12.12 mg dL−1) for hypothermia group (p = 0.001) and lactate (3.36 mmol L−1) for cranial percussion (p = 0.004), 0.028 nmol lipid oxidation in hypothermia treatment (p = 0.009), and 0.134 nmol carbonyls/mg protein (p = 0.001) were observed. There was a reduction in luminosity (p = 0.010) and red intensity (p = 0.001) in the group of fish fillet that received cranial percussion, however, there was no difference in the group stunned by hypothermia. Clove essential oil demonstrates effectiveness in pre-slaughter stress mitigation, influencing the antioxidant system positively. Its usage in pre-slaughter protocols could contribute to improved fillet quality, presenting a promising alternative for enhancing tilapia welfare during slaughter.

Keywords

• Animal welfare
• glutathione
• hypothermia
• lipid oxidation
• protein oxidation
• cranial percussion