Effect of electrical water bath stunning on physical reflexes of broilers: evaluation of stunning efficacy under field conditions

Abstract

The effects of different amounts and frequencies of stunning sine wave alternating current were investigated under field conditions. Seven hundred and fifty broilers were stunned in an electrical water bath with an average root mean square (RMS) current of 150, 200, and 250 mA and frequencies of 200, 400, 600, 800, and 1,200 Hz. The occurrence of corneal reflex, spontaneous eye blinking, and a positive response to a painful stimulus were monitored and recorded immediately after the stunning and at 20 s post-stun. Statistical analysis showed that the electrical stunning frequency (P=0.0004), the stunning RMS current (P<0.0001) and the interaction between stunning frequency and stunning current (P<0.0001) had a significant effect on the occurrence of animals experiencing an abolition of corneal reflex at 20 s post-stun.At a current of 150 mA, the probability of a successful stun was over 90% at 200 Hz, approximately 40% at 400 Hz, and below 5% for frequencies greater than 600 Hz. So, stunning at frequencies greater than 600 Hz cannot be recommended when a RMS current of 150 mA is applied. The maximum probability of a successful stun was obtained for a current level of 200 mA at 400 Hz and for a current level of 250 mA at 400 and 600 Hz, whereas the stunning treatments at 1,200 Hz provided the lowest probability of a successful stun. Assessment of spontaneous eye blinking and responses to comb pinching confirmed the indications coming from the analysis of corneal reflex.

The Influence of Broilers’ Body Weight on the Efficiency of Electrical Stunning and Meat Quality under Field Conditions

“…According to the Eu Regulation n. 1099/2009, FBO may use a wide range of frequency values (up to 1500 Hz) and a current intensity, ranging from 100 to 200 mA. FBO may use, therefore, different combinations of electrical parameters in order to safeguard both animal welfare and the possible downgrading of meat minimizing economic losses [ 2 , 8 , 25 , 26 ]. The amount of the current has great importance on stunning efficiency, and it is proven that currents below 100 mA do not reach an adequate level of unconsciousness [ 10 ].…”

“…In the present study, a low percentage of animals (around 1%) showed signs of stunning ineffectiveness. It has been previously reported that when low intensities are applied, high electrical frequencies are less effective in overcoming impedance in the tissues of the birds leading to a short period of unconsciousness in the animals [ 2 , 22 ]. The outcomes of the present work confirm the efficacy of high frequency combined with the high root mean square current up to 200 mA as already reported by Raj [ 25 ] and Girasole [ 2 ].…”

“…Animal welfare during stunning and slaughter is a matter of public concern that affects product quality, food safety, and the healthiness of consumers. In this context, there is an increasing interest of stakeholders to develop accurate and efficient techniques able to protect animals during these operations [ 1 , 2 ].…”

“…According to the Eu Regulation n. 1099/2009, Food Business Operators (FBO) may use a wide range of frequency values (up to 1500 Hz). High frequencies improve meat quality; however, they have a shorter stun effect on animals, leading to a quick return to consciousness [ 2 , 11 , 18 ], while low frequencies may cause death but, due to strong muscle contractions, post-mortem defects and hemorrhages may appear [ 9 , 19 ]. For these reasons, an electrical frequency > 300 Hz is usually applied to safeguard the quality of the poultry carcass [ 20 ].…”

Slaughter of animals: poultry

“…In a more recent study using a multiple‐bird waterbath stunner under slaughterhouse conditions, Girasole et al. () investigated the effectiveness of stunning broilers with average RMS currents of 150, 200 and 250 mA and frequencies of 200, 400, 600, 800 and 1,200 Hz delivered using sinewave AC. Occurrence of the corneal reflex, spontaneous eye blinking, and a positive response to a painful stimulus were monitored and recorded as indicators of consciousness immediately after the stunning and at 20 s post‐stun.…”