Negative impact of spinal cord section and termonarcosis on welfare and meat quality of Nile tilapia

Abstract

This work aimed to compare the effects of two stunning methods on welfare and meat quality of Nile tilapia (Oreochromis niloticus) and to investigate the slaughter instrument influence on the length of cord section technique. The time for loss of spontaneous behaviors, reflexes, as well as the response to pain of 30 fish submitted to spinal cord section (SM) and termonarcosis (TN) were evaluated. Meat rigor-mortis and pH were also measured. Knifes with bilateral (LB) and unilateral (LU) cutting-edge were analyzed in 10 fish per treatment. Unconsciousness was observed after medians of 82 and 750 seconds for SM and TN, respectively (p< 0.01). Rigor-mortis and pH did not show significant difference between treatments (p> 0.05). The medians for SM application were of 21.5 and 35.0 seconds for LB and LU, respectively (p<0.01). It was concluded that SM is a superior alternative than TN in terms of stunning period, minimizing the time of technique application considerably. Once the instrument influences on SM duration it is necessary to refine the SM technique in order to promote unconsciousness in a shorter period of time.