The Impact Of Colony Cages On Chicken Welfare
Amid growing advocacy for cage-free environments, the animal agriculture industry is proposing alternative cage systems. For example, colony cages are multi-tiered structures for so-called “broiler chickens,” allegedly offering better hygiene and reducing injuries and infections associated with contaminated flooring. However, it’s unclear how these systems compare to conventional litter-based, cage-free environments.
To investigate the welfare claims associated with colony cages, researchers conducted a systematic review of 23 studies with a specific focus on the use of slatted floors in such systems. The aim of their review was to evaluate high-quality research papers about the welfare impacts of caged or slatted-floor systems compared to litter-based flooring.
Overall, the studies yielded mixed results. Litter-based systems showed better welfare in 29 cases, slatted floors in 31 cases, and there were no significant differences in 27 cases. These findings suggest that the welfare implications of different broiler chicken housing systems are complex and not fully understood.
However, upon further investigation, the authors noted several methodological limitations to the papers they evaluated. For example, for most of the papers, assessing animal welfare was not the main goal of the studies. Many focused on measuring production or “performance” of the animals instead. Furthermore, only four of the studies looked at the behavioral components of welfare — a very important factor of welfare assessments — of which none favored slatted floors. This raises concerns about the potential behavioral deprivation that broiler chickens may experience in modern cage systems.
Promised improvements in welfare associated with colony cages, such as reduced footpad dermatitis, hock burn, and breast blisters, were not consistently supported by the evidence in the reviewed studies. This suggests that colony cage systems may not be a clear-cut advantage over litter-based, cage-free housing. Thus, the claims of superiority made by the animal agriculture industry are not fully supported by scientific evidence.
Given the limitations identified in the studies and the concerns surrounding the welfare impacts of colony cages, the researchers caution against their implementation. They argue that colony cages are especially harmful to behavioral welfare (for example, by preventing chickens from carrying out certain natural behaviors like dust bathing). The way these systems are built makes it inherently difficult to overcome the welfare problems, and the lack of space and limited opportunities for natural behaviors in colony cages remain major concerns.
Instead, advocates focused on improving chicken welfare should focus on improving the issues associated with cage-free litter flooring versus switching to colony cages. For example, the authors recommend exploring cameras to monitor chicken behavior in litter-based systems. Furthermore, researchers should look at chicken behavior in future studies about the welfare impacts of housing systems. Behavior is a key component of welfare that can’t be ignored.
https://www.mdpi.com/2076-2615/12/21/2988