The Welfare Footprint Institute (WFI) argues the opposite by adding up hours of pain experienced by an average chicken in different systems[17]. With their model, cage-free aviaries have lower pain scores than conventional cages. However, these results are heavily dependent on what harms are included, how they are scored, and how different types of pain are weighed. Deprivation of natural behaviours accounts for most of the difference in scores. Chronic fear and stress from violence is not included.
I wonder if you are overestimating the uncertainty here. I speculate there is like a 2â3 chance that cage-free layers have higher welfare than ones in furnished cages. The results from WFIâs analysis are below. I think the lines cover the 95 % confidence intervals (CIs). Based on the harms considered, cage-free layers experience less annoying and hurtful pain than ones in furnished cages, and it is unclear whether they experience more or less disabling and excruciating pain. However, âThe analysis primarily aimed to estimate the minimum welfare improvement associated with transitioning to cage-free housing. In this sense, we preferred to err on the side of caution than potentially overestimated reform benefits in any particular aspect. Thus, it is reasonable to anticipate that the actual benefits of this transition may surpass the estimates [below]â (see the 6 bullets in the piece elaborating on why). In agreement with this, Rethink Priorities (RP) got 3 animal welfare scientist to replicate 4 cumulative pain estimates from WFI, and found these âconsistently erred on the conservative sideâ.
We have very limited data on electrical shrimp stunning that doesnât support a confident conclusion as to whether itâs good or bad.
Here is a review of stunning methods for shrimp from Nino OâShea-Nejad published in February.
Overall, the evidence indicates that electrical stunning has greater potential than chilling to induce insensibility, while chilling may suppress behaviour without eliminating sensory processing. Crucial uncertainty remains regarding defining species-appropriate electrical stunning parameters and translating neural evidence into reliable operational standards. On this basis, the report outlines implications for research priorities, regulatory standards, and industry practices aimed at ensuring that humane stunning practices reliably induce insensibility.
Unlike the other two examples, alternative proteins are unlikely to cause harm.
Alternative proteins may decrease the welfare of farmed animals by decreasing the population of farmed animals with positive lives? I estimated cage-free layers and slower growth broilers have negative, but close to neutral lives, and I would not be surprised if they have positive lives. 64.3 % (= 1 â 0.357) of layers in the European Union (EU) were outside cages in 2025, and funding work on alternative proteins does not have an immediate effect. It could be that it mostly reduces the consumption of eggs in 10 years, when the fraction of cage-free layers will likely be higher, and mortality lower due to improvements from experience. So I can see, for example, Coefficient Givingâs (CGâs) grants to Dansk Vegetarisk Forening (DVF) leading to fewer layers in the EU with positive lives.
In addition, alternative proteins may harm wild animals?
Significant additional funding and talent should be allocated to raise the bar for animal welfare interventions by building R&D infrastructure that can rapidly generate high-quality action-relevant research results.
I agree impact-focussed funders underrate such research relative to supporting existing interventions. In addition, I think they underrate research on animal sentience, and, more broadly, on comparing welfare across species. I believe there is huge uncertainty, and ways of decreasing it. Here is some context about my uncertainty. In Bob Fischerâs book about comparing welfare across species, the tentative sentience-adjusted welfare range of shrimps is 8.0 % of that of humans. Welfare range is defined there as the difference between the maximum and minimum welfare per unit time among ârealistic biological possibilitiesâ. For sentience-adjusted welfare ranges proportional to âindividual number of neuronsâ^âexponentâ, and âexponentâ from 0 to 2, which covers the best guesses that I consider reasonable, the sentience-adjusted welfare range of shrimps is 10^-12 to 1 times that of humans.
Even some of the most prominent animal welfare interventions have surprisingly weak evidence behind them. In some cases, the available evidence even suggests that the intervention may be causing harm.
I would be curious to know your thoughts about effects on soil invertebrates. I wouldstill have very little idea about whether cage-free egg campaigns, and electrically stunning shrimps increase or decrease welfare in expectation even if I was certain they increased the welfare of chickens and shrimps. I think their effects on soil invertebrates may be much larger or smaller than those on their target beneficiaries. This is another reason for prioritising research on comparing welfare across species.
As I say in the post, I think that the WFI analysis does not include some potentially significant harms (such as chronic stress/âpain from violence or parasitesâwhich are likely higher in cage-free systems).
I also think that itâs not obvious how to score pain from behavioural deprivation, which accounts for a majority of the difference:
More generally, I think we currently just do not have enough data to make strong claims around the total cumulative pain chickens experience. Under âresearch gapsâ, WFI itself states the following:
Surprisingly little research has been dedicated to the understanding of the impact of different welfare challenges at the individual level (where suffering occurs). Little is known about clinical evolution of the various welfare issues affecting commercial layers (e.g. healing times, duration of exposure), the likelihood of different clinical outcomes, rates of recurrence, and how adversely welfare harms are perceived by the individuals affected. Similarly, knowledge on case-fatality rates, comorbidity patterns and the prevalence of different conditions over the laying cycle is scant.
The independent assessment that Rethink Priorities organised only looked at two layer hen harms: peritonitis in conventional housing; and fractures during depopulation and transport in conventional housing. Neither was related to behavioural deprivation.
Additionally:
Raters were restricted to the references that Welfare Footprint Institute cited in the chapter where the original estimates appeared. Therefore, disagreement among raters is due to how different scientists use the same evidence, rather than which evidence they examine in the first place.
Re: shrimp stunning
The review you link relies heavily on data from other species. My post addresses all the published evidence for Whiteleg shrimp.
I donât want to be overly dismissive of WFI here. They are trying to do something really difficult and important. They have spent years on this work.
However, I think many have been overly confident in acting on their conclusions when they themselves highlight a need for more research.
I agree with all your points. I suspect your guess for the probability of cage-free systems being better than furnished cages is lower than my guess of 2â3. However, I do not think this matters much. In practice, I would still generally prioritise research on decreasing the uncertainty over cage-free egg campaigns.
As I say in the post, I think that the WFI analysis does not include some potentially significant harms (such as chronic stress/âpain from violence or parasitesâwhich are likely higher in cage-free systems).
It also excludes foot lesions and air quality, which are discussed in section âImportant Considerationâ of Chapter 9 of the book Quantifying Pain in Laying Hens by Cynthia Schuck-Paim and Wladimir Alonso from WFI. Here are their conclusions.
[...] the reporting of the relatively low incidence of the more severe and painful manifestations [of foot lesions] in layers [16,21â23] makes it unlikely that consideration of this harm would affect the estimates substantially to the point of changing any of the conclusions.
[...]
[...] it is not unreasonable to suppose that through the potentially detrimental effect on the respiratory system [24] and on mucous membranes, high concentrations of ammonia can lead to a prolonged state of discomfort [26]. This is an important welfare concern, which is likely to increase the estimated time in pain endured in cage-free facilities, depending on the prevalence of (cage and cage-free) facilities where manure is not regularly removed and the ventilation flow is insufficient, and on the time endured in discomfort (e.g. in temperate regions, higher levels of ammonia in cage-free relative to cage housing have been found in winter, but not in summer [27,28]).
Hi Amanda. Great post.
I wonder if you are overestimating the uncertainty here. I speculate there is like a 2â3 chance that cage-free layers have higher welfare than ones in furnished cages. The results from WFIâs analysis are below. I think the lines cover the 95 % confidence intervals (CIs). Based on the harms considered, cage-free layers experience less annoying and hurtful pain than ones in furnished cages, and it is unclear whether they experience more or less disabling and excruciating pain. However, âThe analysis primarily aimed to estimate the minimum welfare improvement associated with transitioning to cage-free housing. In this sense, we preferred to err on the side of caution than potentially overestimated reform benefits in any particular aspect. Thus, it is reasonable to anticipate that the actual benefits of this transition may surpass the estimates [below]â (see the 6 bullets in the piece elaborating on why). In agreement with this, Rethink Priorities (RP) got 3 animal welfare scientist to replicate 4 cumulative pain estimates from WFI, and found these âconsistently erred on the conservative sideâ.
Here is a review of stunning methods for shrimp from Nino OâShea-Nejad published in February.
Alternative proteins may decrease the welfare of farmed animals by decreasing the population of farmed animals with positive lives? I estimated cage-free layers and slower growth broilers have negative, but close to neutral lives, and I would not be surprised if they have positive lives. 64.3 % (= 1 â 0.357) of layers in the European Union (EU) were outside cages in 2025, and funding work on alternative proteins does not have an immediate effect. It could be that it mostly reduces the consumption of eggs in 10 years, when the fraction of cage-free layers will likely be higher, and mortality lower due to improvements from experience. So I can see, for example, Coefficient Givingâs (CGâs) grants to Dansk Vegetarisk Forening (DVF) leading to fewer layers in the EU with positive lives.
In addition, alternative proteins may harm wild animals?
I agree impact-focussed funders underrate such research relative to supporting existing interventions. In addition, I think they underrate research on animal sentience, and, more broadly, on comparing welfare across species. I believe there is huge uncertainty, and ways of decreasing it. Here is some context about my uncertainty. In Bob Fischerâs book about comparing welfare across species, the tentative sentience-adjusted welfare range of shrimps is 8.0 % of that of humans. Welfare range is defined there as the difference between the maximum and minimum welfare per unit time among ârealistic biological possibilitiesâ. For sentience-adjusted welfare ranges proportional to âindividual number of neuronsâ^âexponentâ, and âexponentâ from 0 to 2, which covers the best guesses that I consider reasonable, the sentience-adjusted welfare range of shrimps is 10^-12 to 1 times that of humans.
I would be curious to know your thoughts about effects on soil invertebrates. I would still have very little idea about whether cage-free egg campaigns, and electrically stunning shrimps increase or decrease welfare in expectation even if I was certain they increased the welfare of chickens and shrimps. I think their effects on soil invertebrates may be much larger or smaller than those on their target beneficiaries. This is another reason for prioritising research on comparing welfare across species.
Thanks for engaging!
Re: cage-free welfare estimates
As I say in the post, I think that the WFI analysis does not include some potentially significant harms (such as chronic stress/âpain from violence or parasitesâwhich are likely higher in cage-free systems).
I also think that itâs not obvious how to score pain from behavioural deprivation, which accounts for a majority of the difference:
More generally, I think we currently just do not have enough data to make strong claims around the total cumulative pain chickens experience. Under âresearch gapsâ, WFI itself states the following:
The independent assessment that Rethink Priorities organised only looked at two layer hen harms: peritonitis in conventional housing; and fractures during depopulation and transport in conventional housing. Neither was related to behavioural deprivation.
Additionally:
Re: shrimp stunning
The review you link relies heavily on data from other species. My post addresses all the published evidence for Whiteleg shrimp.
I donât want to be overly dismissive of WFI here. They are trying to do something really difficult and important. They have spent years on this work.
However, I think many have been overly confident in acting on their conclusions when they themselves highlight a need for more research.
I agree with all your points. I suspect your guess for the probability of cage-free systems being better than furnished cages is lower than my guess of 2â3. However, I do not think this matters much. In practice, I would still generally prioritise research on decreasing the uncertainty over cage-free egg campaigns.
It also excludes foot lesions and air quality, which are discussed in section âImportant Considerationâ of Chapter 9 of the book Quantifying Pain in Laying Hens by Cynthia Schuck-Paim and Wladimir Alonso from WFI. Here are their conclusions.