Because they require more feed, although there is large uncertainty about whether this is the case for cage-free reforms. Below are the relevant paragraphs of the post where “I estimated broiler welfare and cage-free reforms increase cropland by 1.98 m2-year/meat-kg and 0.113 m2-year/egg-kg”.
Broiler welfare reforms
From Figure 4 of Gittins et al. (2024), broilers in a conventional scenario need 2.75 feed-kg/meat-kg, and ones in a reformed (slower growth) scenario, corresponding to the European Chicken Commitment (ECC), need 3.70 feed-kg/meat-kg. So I suppose broiler welfare reforms increase feed by 0.950 feed-kg/meat-kg for no change in price.
I suppose meat from broilers in reformed scenarios costs 1.10 times as much as that from broilers in conventional scenarios, which is the mean across the Netherlands, Germany, France, Italy, Spain, and Poland according to Figure 3 of van Horne and Vissers (2022), which analysed the cost of ECC. For a price elasticity of demand for chicken meat of −0.07, as in Table 2 of Bouyssou et al. (2024), that implies broiler welfare reforms decrease the consumption of chicken meat by 1.12 %, which decreases feed by 0.0308 feed-kg/meat-kg. Subtracting this from the increase in feed for no change in price, I determine an increase in feed of 0.919 feed-kg/meat-kg.
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Cage-free reforms
I asked Gemini 2.5 Pro (experimental) on 11 April 2025 about the feed conversion ratio (FCR) of current egg production. Gemini provided a range of 1.9 to 2.1 feed-kg/egg-kg for cages, and 2.0 to 2.2 feed-kg/egg-kg for barns. The means between the lower and upper bounds of the ranges for cages and barns are 2.00 and 2.10 feed-kg/egg-kg, so I assumed cage-free reforms increase feed by 0.100 feed-kg/egg-kg for no change in price. From Table 3 of Leinonen et al. (2012), which studied egg production in the United Kingdom (UK), hens in cages and barns consume 2.56 and 2.74 feed-kg/egg-kg, which imply cage-free reforms increase feed by 0.178 feed-kg/egg-kg. The lower increase suggested by Gemini’s values might be explained by the faster growth of cage-free production since 2012, which facilitates economies of scale. It makes sense hens in barns need more feed because they can move around, and therefore spend more energy.
I suppose eggs from hens in barns cost 1.10 times as much as those from hens in cages, which is the ratio between the mean cost in the 7 days before 9 April 2025 of class A eggs from hens in cages and barns in the EU of 2.60 and 2.85 €/egg-kg. For a “commonly assumed” price elasticity of demand for eggs of −0.15, that implies cage-free reforms decrease the consumption of eggs by 1.37 %, which decreases feed by 0.0274 feed-kg/egg-kg. Subtracting this from the increase in feed for no change in price, I determine an increase in feed of 0.0726 feed-kg/egg-kg.
I guess because cage-free chickens can move around, and therefore spend more energy. Importantly, I expect the effects on soil nematodes, mites, and springtails to be larger than those on laying hens regardless of whether cage-free chickens increase or decrease cropland. I estimated cage-free reforms benefit laying hens 0.718 % as much as they benefit soil nematodes, mites, and springtails for an increase in feed of 3.63 % (= 0.0726/2.00). So, for the effects on laying hens to be larger than those on soil nematodes, mites, and springtails, the change in feed would have to be smaller than 0.0261 % (= 0.00718*0.0363) holding other factors constant, which is very small.
Why do cage free reforms increase crop land?
Hi Matthew,
Because they require more feed, although there is large uncertainty about whether this is the case for cage-free reforms. Below are the relevant paragraphs of the post where “I estimated broiler welfare and cage-free reforms increase cropland by 1.98 m2-year/meat-kg and 0.113 m2-year/egg-kg”.
Why does being cage free need more feed?
I guess because cage-free chickens can move around, and therefore spend more energy. Importantly, I expect the effects on soil nematodes, mites, and springtails to be larger than those on laying hens regardless of whether cage-free chickens increase or decrease cropland. I estimated cage-free reforms benefit laying hens 0.718 % as much as they benefit soil nematodes, mites, and springtails for an increase in feed of 3.63 % (= 0.0726/2.00). So, for the effects on laying hens to be larger than those on soil nematodes, mites, and springtails, the change in feed would have to be smaller than 0.0261 % (= 0.00718*0.0363) holding other factors constant, which is very small.