Diversity, not uniformity: slaughter and electrical waterbath stunning procedures in Belgian slaughterhouses

Relevant Indicators of Consciousness after Waterbath Stunning in Turkeys and Stunning Efficiency in Commercial Conditions

The prevalence and inter-observer repeatability of the four most valid and feasible indicators of consciousness after waterbath stunning in turkeys were evaluated before bleeding (i.e., tonic convulsion, breathing, spontaneous blinking and vocalization) and during bleeding (i.e., fluttering, breathing, spontaneous swallowing and head shaking). Furthermore, correlations between them were calculated to further understand the association between such indicators. This study compared the assessments of four observers on 7877 turkeys from 28 flocks slaughtered in eight different abattoirs. Repeatability between observers was assessed by combining the crude percentage of agreement and the Fleiss' kappa. Before bleeding, tonic seizure was observed to be not reliable under commercial conditions and spontaneous blinking and vocalization had poor repeatability. During bleeding, spontaneous swallowing was not observed and head shaking had poor repeatability. Hence, the most relevant indicators of consciousness before bleeding is breathing while during bleeding is breathing and wing flapping. Moreover, the stunning efficiency of the key electrical parameters used in the different slaughterhouses was assessed. Therefore, a refined list of indicators of the state of consciousness after waterbath stunning is proposed to be used in commercial turkey slaughterhouses to ensure consistency of controls. On the other hand, the range of the prevalence of turkeys with indicators of consciousness within a batch found before bleeding [0-16%] and after bleeding [0-18%] highlights the importance of controls.

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

Simple Summary

Water-bath stunning represents the most-applied stunning system in poultry slaughtering. This study aimed to assess the efficiency of two types of electrical equipment applied to broilers with different live body weights. Moreover, the influence of the tested stunners on broiler meat quality was evaluated. 6600 broilers, divided into three weight groups, were stunned and the state of unconsciousness and post-mortem defects were evaluated by blinded trained operators. Considering the total body weight, the application of the two stunning systems resulted in a different occurrence of ineffective stunning signs registering statistical differences (p < 0.01) among groups. Considering injuries, an inverse relationship between body weight and lesions was found. The results highlighted the effectiveness of both stunning systems that apply the best combination of electrical parameters, taking into account the weight of the animal and ensuring its welfare.

Abstract

Water-bath stunning represents the most-applied stunning system in poultry slaughtering, but within the European Union, specific indications on electric parameters that should be used, such as voltage, are missing. The objective of this study was to evaluate the efficiency of two commercially available types of electrical equipment (A and B) on broilers with different live body weights and the influence of the tested parameters on meat quality. Experimental trials in a European Union-approved slaughterhouse were carried out using two different stunners. 6600 broilers, divided into three weight groups, were stunned applying different protocols based on the same current frequencies and intensity but different voltages. The state of unconsciousness (presence of corneal reflex and wings flapping) and post-mortem defects (pectoral hemorrhages and dark meat) were evaluated by blinded trained operators. The presence of corneal reflex and petechiae were the most reported consciousness signs and post-mortem injuries, respectively. Different weights played an important role within stunner A, registering statistical differences (p < 0.01) among groups. Considering injuries, an inverse relationship between body weight and lesions was found. The results highlighted the effectiveness of both stunning systems applying the best combination of electrical parameters considering the weight of the animal and ensuring its well-being.

Head-Only Stunning of Turkeys Part 2: Subjective and Objective Assessment of the Application of AC and DC Waveforms

Simple Summary

In this study, we investigated various types of application of head-only electrical stunning to turkeys, in order to improve the effectiveness of the stunning process. We used recordings of physical responses and of electroencephalograms (EEGs) to assess effectivity of stunning and various waveforms: alternating current (AC) and pulsed direct currents (DC). Depending on the waveforms, voltages between 125 and 250 V produced an effective stun in turkeys in this study.

Abstract

Electrical stunning is likely to remain an important stunning method for turkeys at slaughter. The purpose of this study is to understand the application of various waveforms of alternating current (AC) and pulsed direct currents (DC), head-only, to turkeys and to improve the effectiveness of handheld stunning of turkeys. We evaluated the effectiveness of stunning by documenting physical responses and recording electroencephalograms (EEGs). For the assessment of physical responses, the stunning voltage was varied depending on the proportion of animals effectively stunned at a certain voltage level. If all turkeys in a group of 10 were stunned, the voltage was decreased, and the next group was stunned. This was repeated until not all turkeys showed signs of being effectively stunned. The experiment was then repeated at the voltage level just above the one that showed incomplete effective stunning. The effects of the stunning on the EEG recording was assessed in 16 turkeys to measure the occurrence of epileptiform EEGs, in 14 turkeys to assess epileptiform EEGs after neck-cut (bleeding), and in 14 turkeys to assess the effect of increased voltage and reduced frequency on epileptiform EEGs. Assessing EEGs in a laboratory setting contributes considerably to the understanding of electrical stunning procedures. Voltages between 125 and 250 V, depending on the waveform assessed, were effective in producing an effective stun in turkeys in this study.

Head-Only Stunning of Turkeys Part 1: The Minimum Voltage Necessary to Break Down the Inherent High Resistance

Simple Summary

Pre-slaughter stunning is required for the humane slaughter of turkeys. For the head-only electrical stunning to be effective, the impedance (resistance) in the tissue of the head of the animal between the two electrodes must be overcome by the level of the voltage used. We have assessed the most appropriate voltage to effectively overcome the impedance and provide an effective stun, and that is also safe for the operator to use. Sinusoidal AC at 150 V and 50 Hz was considered to fulfil those requirements and was used for further testing.

Abstract

Pre-slaughter stunning is required for humane slaughter. For turkeys, head-only electrical stunning is most often used by small scale producers. To ensure immediate and effective stunning, the impedance (resistance) of the tissue of the head of the animal situated between the two electrodes needs to be overcome swiftly. The impedance is a function of the voltage and decreases non-linearly with increasing voltage. In this paper, we describe a method to assess the minimum voltage needed at which the impedance no longer decreases, that is likely to produce an effective stun. For ethical reasons, gas stunned, electrically naïve turkeys were used to measure impedance at various levels of voltage and current. Several combinations of voltage and frequency, alternate current (AC), direct current (DC) and pulsed DC, were identified that would be sufficient to achieve the maximum decrease in the impedance, and therefore would allow the highest current and the most effective stun. A minimum, expressed as Root Mean Squared voltage, of 150 V and 50 Hz. would be required in AC, 175 V in pulsed DC at 30% cycle (150 at 50% cycle), and 225 V if voltage spikes of very short duration were used. Sinusoidal AC applied at 150 V, 50 Hz was selected for further testing.

Broiler stunned state detection based on an improved fast region-based convolutional neural network algorithm

An improved fast region-based convolutional neural network (RCNN) algorithm is proposed to improve the accuracy and efficiency of recognizing broilers in a stunned state. The algorithm recognizes 3 stunned state conditions: insufficiently stunned, moderately stunned, and excessively stunned. Image samples of stunned broilers were collected from a slaughter line using an image acquisition platform. According to the format of PASCAL VOC (pattern analysis, statistical modeling, and computational learning visual object classes) dataset, a dataset for each broiler stunned state condition was obtained using an annotation tool to mark the chicken head and wing area in the original image. A rotation and flip data augmentation method was used to enhance the effectiveness of the datasets. Based on the principle of a residual network, a multi-layer residual module (MRM) was constructed to facilitate more detailed feature extraction. A model was then developed (entitled here Faster-RCNN+MRMnet) and used to detect broiler stunned state conditions. When applied to a reinforcing dataset containing 27,828 images of chickens in a stunned state, the identification accuracy of the model was 98.06%. This was significantly higher than both the established back propagation neural network model (90.11%) and another Faster-RCNN model (96.86%). The proposed algorithm can complete the inspection of the stunned state of more than 40,000 broilers per hour. The approach can be used for online inspection applications to increase efficiency, reduce labor and cost, and yield significant benefits for poultry processing plants.