To cope with the growing consumer demand for fish, recently the aquaculture industry has intensified its production (FAO, 2022). This implies an increased level of stressors that may compromise fish health and survival. Also, fish welfare is gaining increasing importance in global aquaculture (Pedrazzani et al., 2022). Stressors such as handling, selection, vaccination and transportation can reduce fish stress responses and resistance (Martos-Sitcha et al., 2020). For instance, the stress related to fish transportation impair fish health and welfare inducing undesirable side effects such as reduced growth, infections, and mortality (Ciji & Akhtar, 2021a; de Oliveira et al., 2022a; Sampaio & Freire, 2016a). To prevent stress and related negative effects on fish health, several studies have suggested to blandly sedate fish before leading specific stressful practices. The use of water and feed additives is also suggested to this purpose (Aydın & Barbas, 2020; Yousefi et al., 2022). Among mineral feed additives, MgCl2 is the most applied relaxant for research and commercial applications (Azizan et al., 2021). MgCl2 sedative action is attributed to the magnesium ions (Mg2+), which serve as a calcium channel blocker, preventing calcium ions (Ca2+) from entering the cell. Fare clic qui per immettere testo. Aim of the study was to investigate the potential toxicity and sedative effects on larvae exposed to 6 different water concentration of AFI Calm™ (Mg rich mineral feed), on zebrafish eggs hatchability, post-hatching survival, larvae locomotion and mRNA gene expression. The results showed toxicity effect and reduced survival rate at 1 mg ml-1 and 5 mg ml-1 water concentrations. No differences between treatments were observed for eggs hatchability. Locomotor performances showed sedative effect already at the lowest concentration of AFI Calm™ (0.125 mg ml-1), with a dose-dependent effect. The qRT-PCR performed on stress-related genes showed that AFI Calm™ induced down-regulation of pomca, even at the lowest concentration. For a contrary, AFI Calm™ induced an over-expression of serta and hsp70 genes at the highest concentration (0.250 mg ml-1 and 0.5 mg ml-1, respectively). In conclusion, the water exposure of zebrafish larvae to low doses of AFI Calm™ showed no negative effects on eggs hatchability and embryo post-hatching survival and induced lower locomotor performances already at the lowest concentration. These findings support the hypothesis that magnesium might have sedative effects on fish and opening new opportunities for applications in the aquaculture sector.
Effect of a mineral feed additive on the swimming behaviour of fish larvae as an indicator of sedation status
Sangiacomo Chiara;Rosario Licitra;Baldassare Fronte.
2023-01-01
Abstract
To cope with the growing consumer demand for fish, recently the aquaculture industry has intensified its production (FAO, 2022). This implies an increased level of stressors that may compromise fish health and survival. Also, fish welfare is gaining increasing importance in global aquaculture (Pedrazzani et al., 2022). Stressors such as handling, selection, vaccination and transportation can reduce fish stress responses and resistance (Martos-Sitcha et al., 2020). For instance, the stress related to fish transportation impair fish health and welfare inducing undesirable side effects such as reduced growth, infections, and mortality (Ciji & Akhtar, 2021a; de Oliveira et al., 2022a; Sampaio & Freire, 2016a). To prevent stress and related negative effects on fish health, several studies have suggested to blandly sedate fish before leading specific stressful practices. The use of water and feed additives is also suggested to this purpose (Aydın & Barbas, 2020; Yousefi et al., 2022). Among mineral feed additives, MgCl2 is the most applied relaxant for research and commercial applications (Azizan et al., 2021). MgCl2 sedative action is attributed to the magnesium ions (Mg2+), which serve as a calcium channel blocker, preventing calcium ions (Ca2+) from entering the cell. Fare clic qui per immettere testo. Aim of the study was to investigate the potential toxicity and sedative effects on larvae exposed to 6 different water concentration of AFI Calm™ (Mg rich mineral feed), on zebrafish eggs hatchability, post-hatching survival, larvae locomotion and mRNA gene expression. The results showed toxicity effect and reduced survival rate at 1 mg ml-1 and 5 mg ml-1 water concentrations. No differences between treatments were observed for eggs hatchability. Locomotor performances showed sedative effect already at the lowest concentration of AFI Calm™ (0.125 mg ml-1), with a dose-dependent effect. The qRT-PCR performed on stress-related genes showed that AFI Calm™ induced down-regulation of pomca, even at the lowest concentration. For a contrary, AFI Calm™ induced an over-expression of serta and hsp70 genes at the highest concentration (0.250 mg ml-1 and 0.5 mg ml-1, respectively). In conclusion, the water exposure of zebrafish larvae to low doses of AFI Calm™ showed no negative effects on eggs hatchability and embryo post-hatching survival and induced lower locomotor performances already at the lowest concentration. These findings support the hypothesis that magnesium might have sedative effects on fish and opening new opportunities for applications in the aquaculture sector.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
