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Assessment of unconsciousness by electroencephalography - EEG in the process of slaughter in Atlantic COD

Grant number: 18/01584-0
Support type:Scholarships abroad - Research Internship - Doctorate
Effective date (Start): April 09, 2018
Effective date (End): October 13, 2018
Field of knowledge:Agronomical Sciences - Animal Husbandry - Animal Production
Principal Investigator:Elisabete Maria Macedo Viegas
Grantee:Daniel Santiago Rucinque Gonzalez
Supervisor abroad: Johannes Wilhelmus Van de Vis
Home Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
Local de pesquisa : Wageningen University, Netherlands  
Associated to the scholarship:17/15364-9 - Unconsciousness assessment through ELECTROENCEPHALOGRAFY (EEG), in the process of stunning, for ElECTRONARCOSIS, percussion and anesthesia for humane slaughter of Nile Tilapia, BP.DR


INTRODUCTION: recently, the World Organization for Animal Health - OIE, through the Aquatic Animal Code, set recommendations for the welfare of farmed fish, mainly in transport, stunning and killing for human consumption (OIE, 2012). In Brazil, the hypothermia in ice for stunning is used in most fish slaughterhouses (Oliveira Filho et al., 2014). Such method is recognized as highly stressful before loss of consciousness in many fish species (Lambooij et al., 2006; Robb and Kestin, 2002; van de Vis et al., 2003). When an animal is killed, a major welfare concern is to avoid or minimize discomfort. Thus, stunning is typically applied to animals to induce unconsciousness and insensibility to pain stimuli for sufficient duration to secure that an animal does not recover during exsanguination (Lambooij et al., 2008). Unconsciousness may be assessed through electroencephalography (EEG) (Robb et al., 2000) or behavioral indicators (Kestin et al., 2002). It should be noted that no firm conclusions on loss of consciousness can be drawn on observation of behaviour only (Van de Vis and Lambooij, 2016). The aim of this project is to assess unconsciousness through EEG considering one method for stunning and killing of farmed Atlantic cod. MATERIAL AND METHODS: Atlantic cod (Gadus morhua ) (n=30) will be obtained from a commercial fish farm in Norway. The fish will be then transported with oxygenation at a fish density of 15 kg m-3 for 3 h to laboratory. After 1 d without feed the experiment will begin (Erikson et al., 2012).Registration of EEG and ECG, prior to stunning, individual fish will be equipped with EEG and ECG electrodes. Each individual fish will be equipped with EEG electrodes. To implant the electrodes, each will be anesthetized locally a 10% spray Xylocaine® (lidocaine 100 mg/ml). EEG electrodes (10 mm long and 1.5 mm of diameter; 55% silver, 21% copper, 24% zinc) will be placed through skin and skull: one electrode will be positioned 0.3 cm to the right and one electrode 0.3 cm to the left of the sagittal suture and 4 cm caudally of the imaginary line between the outer cauth of the eyes. ECG electrodes (35 mm long and 1.5 mm of diameter) will be inserted subcutaneously, one caudally to the implantation of the left pectoral fin and one dorsally of the first electrode. A single earth electrode for EEG and ECG will be placed subcutaneously caudally to the dorsal fin. EEG and ECG will be recorded from 30 s before stunning and constantly until they determine the death of fish (Lambooij et al., 2008). A DI 720 data recording module with a WinDaq Waveform browser (Dataq Instruments, Akron, Ohio, USA) will be used. Two channels on the DI 720 data recording module will be use, which gives 250 Hz sample speed for each channel. Noxious stimuli (i.e. needle scratches applied in the mouth) will be administered at 0.5, 1, 2, 3, 4, 5, 7 and 10 min after stunning. Behavioural and EEG responses to administered pain stimuli (needle scratches applied to the dorsal skin) will be monitored at the start of each recording period.Stunning methods: Electrical stunning, we will determine conditions (voltage, amperage, waveform of the electrical current, exposure time to the electricity) to achieve an immediate and irrecoverable stun in farmed cod. When stunning and killing by exposure to electricity is not feasible by using electricity only another method for killing of the stunned fish will be selected.Percussion and Chemical stunning, for assessment of percussion and chemical of fish, no experimental was carried out. EEGs available at Wageningen Livestock Research obtained in previous studies with another fish species will be used by Daniel to practice interpretation of this type of EEGs. IMPLICATIONS: the assessment of unconsciousness through EEG will ensure a method for human slaughter in fish. The assessment of unconsciousness will help in the drafting of regulations for the humane slaughter of fish in Brazil.