Welfare of spent hens in Flemish slaughterhouses: current situation

Despite the rising concern about welfare of laying hens, objective monitoring systems to properly evaluate their welfare are currently still lacking. In this context, a pilot version of a ready-to-use welfare monitoring protocol for spent hens at the level of the slaughterhouse was developed. Data was gathered by means of questionnaires in a custom made mobile application according to the following protocol. First, the flock behavior and climate were inspected during lairage. Next, a range of animal-based indicators were scored on a random subset of 100 animals per flock after stunning. Scoring of plumage on 6 body parts, skin injuries in 3 zones and dermatitis was done on a 1 (severe damage) -4 (perfect condition) point scale according to Tauson et al. (2005; Anim. Sci. Pap. Rep, 23(Suppl 1), 153-159). Comb injuries were scored on a 0 (no injuries)-2 point scare. Keel bone fractures and deviations were detected by palpation. Subsequently, after defeathering, counts of fresh fractures and bruises on wings, legs and breast were registered during a 2 times 5 min inspection at the slaughter line.
Lastly, death on arrivals, rejects and information on rearing conditions (e.g. housing system, egg color, flock age…) were copied from the slaughterhouse documents. Between November 2021 and February 2023, 49 Flemish flocks were monitored with this pilot protocol. For each indicator the mean score or the prevalence per flock (experimental unit) was calculated. Statistical analysis was performed using the GLM procedure in RStudio (version 2022.07.2). Values are displayed as means ± standard error. Mean plumage scores were 2.2±0.05, 1.9±0.08, 2.0±0.07, 2.4±0.06, 1.4±0.05 and 1.6±0.08 for the neck, back, tail, wings, breast and cloaca zone, respectively. Injuries were rather rare, with mean scores ranging from 3.8±0.02 for the breast region to 4.0±0.01 for the backside. The mean prevalence of keel bone fractures (53.5±2.84%) and deviations (54.5±2.92%) was high, with a significantly lower prevalence of keel bone fractures in hens housed in enriched cages (36.7±4.45%) as compared to floor-management (54.5±3.74%) and aviaries (65.4±3.98%). Remarkable was the high prevalence of bruises at the wing tips (11.9±1.94%) as compared to other body parts (of indicators which will be assessed at the slaughter line, will be chosen. In the future, thresholds for each welfare indicator can be set by the animal welfare authorities. In this way, a stepwise improvement of the welfare of the Flemish laying hens is pursued