Thanks for sharing, Alistair! I recently spent some time looking into this issue, and I don’t think it’s a good EA cause area. Pet food does directly result in the farming of more livestock that I had expected, but Knight overstates his case and doesn’t engage with the rest of the literature.
On scale:
a full global transition would apparently spare around 7 billion land animals each year
This is not true. The paper linked doesn’t explain Knight’s methodology, but if you click through to Knight (2023) you’ll find that the author double-counts a lot of livestock carcasses. Copy-pasting my earlier notes because I’m dashing this comment off, hope it makes sense:
In particular, it claims: “Human meat consumption is responsible for this many animals being farmed directly. And pet food meat consumption is responsible for this many animals being farmed directly, and this many animals being farmed indirectly (i.e., byproducts)”. The total sum of animals therefore double counts the animals who are farmed for both human and pet consumption.
[…]
Andrew’s model in the 2023 paper assumes that animals farmed for pet food ~= animals farmed directly + (ABPs [animal by products] * R), where R is basically the ratio of ABP:meat in an animal body. (I know I’m oversimplifying because he also includes a co-efficient to account for food waste, and so on). This formula means that (a) when put alongside animals farmed for human food, we’re double-counting the animals whose bodies mostly are eaten by people and minorly eaten by pets, and that (b) ABPs are always assumed to have a greater cost in animals lives than meat, which reverses the causal relationship. Byproducts don’t drive production.
The byproducts point is important to appreciate whether, setting the numbers aside, vegan pet food would counter factually reduce the number of animals being farmed. Knight claims that there are other economically productive uses for byproducts; if that’s true, then a reduction in demand for animal-derived pet food would change the marginal use case for byproducts but not reduce their production. That undercuts Knight’s point on scale because so much of the scale falls out of inflated byproduct numbers.
On tractability:
I haven’t dug into the surveys that Knight cites but I’m super skeptical. I know vegans who don’t have vegan pets, and I know how hard it is to make people go vegan. There are big barriers to getting humans to transition to alternative proteins at scale, and that’s only more true for companion animals.
On whether this is EA:
I’m super pleased that some people have looked into this, and I think being able to entertain weird ideas seriously is a great thing. I even think there could be some cool stuff in this space (campaigning for cats and dogs to eat less chicken and fish?).
But to be an EA issue — especially a ‘leading’ issue — it has to be more cost-effective than other good opportunities, and I don’t think it is.
Thanks Seth (good to hear from you)!
I agree with everything here. In particular: a lot of animals are farmed directly for pets, and ~3 billion sounds like a reasonable guess (I think Knight is double counting with ~7 billion). This was an update for me when I looked into this because I had thought almost all pet food was byproducts.
And I might be understating the scale case because I’m bugged by the methodology. But I don’t think the scale case is compelling when we think in terms of animals who could reasonably be taken out of the food system by vegan pet food, instead of number of animals farmed for pet food. This is something that motivates my (stray) thought that promoting beef > chicken/fish for companion animals could be high impact.
I like the Alexander paper but I think economic allocation makes more sense when you’re trying to attribute environmental harms than when you’re trying to reason about the number of animals killed in a counter factual scenario. Looking at the tools from LCA, I’d like to see somebody try a system expansion model here!
Please share the draft with me, I’d like to read it!