Cage-Free Systems For Layers Are Not A Panacea

There are currently almost as many egg-laying hens on the planet — about 7.5 billion — as there are humans. The overwhelming majority of them still spend their lives in battery cages, but as the public learns more about the living conditions endured by these hens, pressure has increased to find more humane alternatives. The European Union has led the way, but by 2020, almost one-quarter of U.S. laying hens (24%) lived in cage-free conditions. While these new systems allow hens to express natural behaviors, there are concerns that these loose systems cause higher hen mortality. Breed selection, changed dietary needs, lighting schemes, unfamiliar rearing and maintenance requirements, and the construction of the cage-free systems themselves could all contribute to adverse outcomes. 

To assess mortality rates, researchers analyzed layer mortality in conventional cages, furnished cages, and cage-free aviaries. For this meta-analysis, they drew data from 29 prior studies or surveys published in English, Spanish, Portuguese, and French. A total of 6,040 commercial flocks with 176 million hens from 16 countries were included in the study. Of these, 4,407 flocks were caged and 1,633 were housed in indoor cage-free systems. The remaining 1,221 flocks lived in tiered aviaries. Rates of death were calculated when the hens were 60 weeks old. Using data from 2000-2020 allowed longitudinal estimates of the changes in mortality rates across time.

Results indicated that, excluding conventional cages, hen mortality declined as experience with the new systems increased. Since 2000, deaths declined .35-.65% per year on average, which translates to a 4-6% drop in mortality over a decade. Indeed, in recent years, these trends have brought the mortality rates from cage-free systems in line with those for conventional caged systems. Rates of death may improve even further as grower knowledge increases and they optimize genetics for these new systems. 

Outcomes from this study fail to support the idea that cage-free systems are more lethal to hens than conventional systems. It takes time to become proficient in any new skill or process, and animal agriculture is no different. That said, death is not the only welfare criterion. Even if layers survive longer in a given system, it doesn’t mean their quality of life is better. For instance, hens in conventional systems may experience weakness, lethargy, and reduced movement, but this may not compromise their egg-laying ability. Just being alive doesn’t mean they are healthy. As the authors put it, “what makes animals suffer is not necessarily what kills them”. 

For advocates, this study is another sobering reminder of the suffering animals endure in our agricultural production systems. Cage-free confinement systems have been shown to lead to better hen welfare, but improvements in mortality apparently take time. We need to continue campaigning for bans on battery cages. At the same time, as this article points out, we need more and better information from growers on how their hens are faring so we can advocate most effectively for what will really matter in hens’ lives.