Welfare Risks of Repeated Application of On-Farm Killing Methods for Poultry

Abstract

Council Regulation (EC) no. 1099/2009 on the protection of animals at the time of killing restricts the use of manual cervical dislocation in poultry on farms in the European Union (EU) to birds weighing up to 3 kg and 70 birds per person per day. However, few studies have examined whether repeated application of manual cervical dislocation has welfare implications and whether these are dependent on individual operator skill or susceptibility to fatigue. We investigated the effects of repeated application (100 birds at a fixed killing rate of 1 bird per 2 min) and multiple operators on two methods of killing of broilers, laying hens, and turkeys in commercial settings. We compared the efficacy and welfare impact of repeated application of cervical dislocation and a percussive killer (Cash Poultry Killer, CPK), using 12 male stockworkers on three farms (one farm per bird type). Both methods achieved over 96% kill success at the first attempt. The killing methods were equally effective for each bird type and there was no evidence of reduced performance with time and/or bird number. Both methods of killing caused a rapid loss of reflexes, indicating loss of brain function. There was more variation in reflex durations and post-mortem damage in birds killed by cervical dislocation than that found using CPK. High neck dislocation was associated with improved kill success and more rapid loss of reflexes. The CPK caused damage to multiple brain areas with little variation. Overall, the CPK was associated with faster abolition of reflexes, with fewer birds exhibiting them at all, suggestive of better welfare outcomes. However, technical difficulties with the CPK highlighted the advantages of cervical dislocation, which can be performed immediately with no equipment. At the killing rates tested, we did not find evidence to justify the current EU limit on the number of birds that one operator can kill on-farm by manual cervical dislocation.

Keywords: animal welfare.; captive bolt; cervical dislocation; killing; poultry; reflexes.

Figure 1

Mechanically-assisted cervical dislocation for turkeys. The bird is restrained in a cone (inverted position). A nylon cord is looped (600 mm) over and behind the head at the cranial/vertebral (C0/C1) junction. Holding the head firmly in place (by hand), the stockworker places his foot through the lower part of the loop situated beneath the bird (off the ground) and forcefully and quickly presses his foot to the floor causing a rapid dislocation of the neck.

Figure 2

Bar chart providing a comparison between the percentage of birds successfully killed (kill success = single kill attempt resulting in rapid death) and the percentage of birds where the method application was optimal (method success = single kill attempt resulting in rapid death and optimal anatomical damage) for each kill method (CPK (n = 1200 birds), cervical dislocation (manual + mechanically-assisted) (n = 1200 birds), manual cervical dislocation alone (n = 800 birds), and mechanically-assisted cervical dislocation alone (n = 400 birds). Note that the Y axis scale starts at 95%.

Figure 3

Bar chart showing the range of cervical dislocation levels achieved in successfully killed birds by cervical dislocation across all stockworkers, described as the proportion of birds (%) dependent on bird type (p < 0.0001).

Figure 4

Comparison of mean (±SE) times of last observations for (a) jaw tone, pupillary, and nictitating membrane; and (b) wing flapping, leg paddling, and cloacal movement post successful method application for all killing methods. Asterisks (*) indicate that there was a significant difference between groups (*** = p < 0.001).