On-farm comparison of keel fracture prevalence and other welfare indicators in conventional cage and floor-housed laying hens in Ontario, Canada

Abstract

The objective of this study was to compare the flock-level prevalence of healed keel bone fractures and to benchmark other indicators of well-being in laying hens housed in conventional cages and single-tier floor housing systems at several points during the production period. Commercial farms in Ontario, Canada, that housed hens in cages (n=9) or floor barns (n=8) were included. Flocks were beak-trimmed brown hens of various strains. Each flock was visited at 20, 35, 50, and 65 wk of age. At each visit, 50 hens were weighed, palpated for healed keel fractures, and feather scored over 4 areas of the body. Data were collected from the farm records on cumulative mortality. Keel fracture prevalence was higher in floor-housed flocks compared to cage-housed flocks (48.3±0.04% vs. 24.8±0.03%; P<0.001). The majority of keel fractures occurred by 50 wk. Cumulative mortality tended to be higher in floor-housed flocks compared to cage-housed flocks (2.13±0.42% vs. 1.29±0.19%; P=0.078). Mean BW was lower (1,827±28.8 g vs. 1,888±26.8 g; P=0.02) yet more uniform (CV of BW 9.43±0.40% vs. 10.10±0.32%; P<0.001) in floor-housed flocks compared to cage-housed flocks. Feather condition was not affected by housing system type (P=0.618), although it declined with age (P<0.001). Individual hen factors assessed using Pearson partial correlations indicated that hens with fractures were heavier at 65 wk in both housing types (P<0.05) and that heavier hens housed on the floor had better feather scores (P<0.001) from 35 wk onward. Floor-housed hens with fractures had lower feather scores at 35 wk (P<0.05) but not at 50 or 65 wk. Housing hens in single-tier floor systems increased the flock-level prevalence of keel fractures and resulted in a lower, yet more uniform, BW compared to hens in conventional cages under commercial conditions in Ontario. Benchmarking welfare indicators from alternative housing systems for laying hens is important to ensure that progress is made in improving their well-being.

Pathological characterization of keel bone fractures in laying hens does not support external trauma as the underlying cause

“…All types of production system experience the problem although cagefree systems have been reported to have the highest occurrence of the problem. Prevalences in non-cage systems have been reported to range from 70 and up to 97% [3][4][5][6][7][8]. However, high prevalences, up to 62%, also has been reported from enriched cages [7,9] PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.0229735 March 9, 2020 1 / 15 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111…”

Causes of keel bone damage and their solutions in laying hens

“…One type of KBD, keel fractures (KF), sometimes referred to as 'old breaks', can be defined as breaks in the bone that will typically manifest as a callus around the fracture site after a few days; KF may also involve sharp, unnatural deviations, or bending of the bone (Wilkins et al, 2004). The problem of keel damage is clearly widespread with similar yet highly variable levels reported in various countries, such as Switzerland (Kappeli et al, 2011); UK (Wilkins et al, 2011); The Netherlands, Belgium, Germany (Rodenburg et al, 2008;Heerkens et al, 2013) and Canada (Petrik et al, 2015). Keel bone damage (KBD) extends across genetic lines (Kappeli et al, 2011) and all types of housing systems (Wilkins et al, 2011;Petrik et al, 2015)including organic production systems (Bestman and Wagenaar, 2014).…”

Effects of conventional and organic rearing systems and hen age on oxidative stress parameters of blood and ovarian tissues in laying hens

“…On the other hand, some researchers (43) reported that feather pecking, high mortality levels and keel bone fractures were significant welfare problems in non-cage rearing systems for laying hens. Petrik et al (34) compared two systems which are floor and cage. They reported that plumage condition was not affected by rearing system.…”