The scale of animal agriculture
In a table, I combine various estimates of the number of animals farmed with Rethink Priorities’ welfare range or moral weight estimates (Fischer, 2023) or my own guesses for others based on them. The table is also accessible here with calculations and some notes for some of the figures.
| Farmed animals | Individual welfare range (Rethink Priorities’ Fischer, 2023, and my own guesses for others in italics) | Total welfare range-years/tonne produced | Total welfare range of those alive at any time (billions) | Welfare range * number killed per year (billions) | Number alive at any time (billions) | Number killed per year (billions) | Total weight of animals harvested per year (millions of tonnes) | Sources for animal numbers and tonnage |
| Pigs | 0.515 | 4.1 | 0.5 | 0.77 | 0.98 | 1.49 | 123 | Šimčikas, 2020 and Our World in Data (a, b) |
| Cattle (and buffaloes) | 0.5 | 11.1 | 0.9 | 0.17 | 1.7 | 0.34 | 76 | Šimčikas, 2020 and Our World in Data (a, b) |
| Sheep and goats | 0.5 | 66.1 | 1.1 | 0.57 | 2.2 | 1.14 | 17 | Šimčikas, 2020 and Our World in Data (a, b) |
| Chickens | 0.332 | 56.6 | 7.9 | 24.9 | 23.7 | 75 | 139 | Šimčikas, 2020 and Our World in Data (a, b) |
| Fish (excluding wild fishery stocking) | 0.089 | 152.8 | 9.2 | 9.9 | 103 | 111 | 60 | Šimčikas, 2020, FAO, 2022 (Figure 13) |
| Fish for wild fishery stocking | 0.089 | 1.3 | 7.1 | 15 | 80 | Šimčikas, 2020, Šimčikas, 2019 | ||
| Decapod shrimp | 0.031 | 1080.3 | 7.1 | 13.6 | 230 | 440 | 6.6 | Waldhorn & Autric, 2023 |
| Insect larvae (2030 projection) | 0.002 | 438.4 | 0.78 | 23.8 | 391 | 11905 | 1.8 | 2030 production projection by de Jong & Nikolik, 2021 (pdf)) |
| Brine shrimp nauplii | 0.0002 | 98630.1 | 0.30 | 108.0 | 1479 | 540000 | 0.003 | Boddy/Shrimp Welfare Project, unpublished, tonnage from The Fish Site, 2019 |
| Total of above | 123.6 | 27.7 | 187.9 | 2245 | 552612 | 224 | ||
| Humans (for comparison) | 1 | 8.1 | 0.061 | 8.1 | 0.061 | Ritchie & Mathieu, 2023 |
Some notes:
When central estimates were not available, I’ve replaced ranges with my own best guess central estimates.
The numbers for insect larvae are based on the projection of production by 2030 by de Jong & Nikolik, 2021 (pdf), for production only in North America and Europe and only for farmed animal feed and pet food, although they expected feed to account for most insect farming, and most investment had been for farms in North America and Europe. I use weights and lifespans reflecting black soldier fly larvae. I use Rethink Priorities’ welfare range estimate for silkworms for them.
Some of the above estimates may not account for pre-slaughter/pre-harvest mortality, so may understate the number alive at a time or that are killed other than by harvest/slaughter.
The figures for “Total weight of animals harvested per year” may be somewhat inconsistent, with some potentially reflecting only meat after removing parts, and others the whole bodies.
There are other farmed animals not included above, but the above seems to account for almost all of them (Šimčikas, 2020, Waldhorn & Autric, 2023).
Brine shrimp nauplii
For some background on brine shrimp (Artemia) nauplii (early larvae), see Van Stappen, 1996, The Fish Site, 2019, Brine shrimp—Wikipedia and Aquaculture of brine shrimp—Wikipedia. They are largely used as feed for fish larvae and decapod shrimp larvae. The number estimates are based on unpublished estimates by Aaron Boddy from Shrimp Welfare Project. I assume, as a guess conditional on being sentient at all, brine shrimp nauplii are sentient for one day before they die, roughly between hatching from the cyst (egg) after being added to tanks as a cyst to feed fish or shrimp larvae, and actually being eaten.
I doubt their (potential) mental capacities have been studied much at all. Their average weights as feed are probably around 5*10^-6 grams,[1] similar to nematodes.[2] Rethink Priorities has been fairly skeptical of nematode sentience, with representative probabilities around 0.4% to 7%, and lower than for silkworms, sea hares and earthworms, and even lower still than for mature insects and decapod shrimp (Schukraft et al., 2019, Duffy, 2023).
I consider brine shrimp nauplii to challenge expected value reasoning and moral aggregation (see Sebo, 2023). I am fairly inclined to ignore them altogether, perhaps no matter their number, or at least discount them more than linearly. This may be partly due to moral uncertainty and partly due to different attitudes towards risk and aggregation. However, further research on their mental capacities could be valuable. Furthermore, the table includes only nauplii, not the breeding stock, who probably have greater individual moral weights.
- ^
180,000 nauplii per gram of (dried?) cysts, according to Alune, 2021 and 0.4*10^-5 grams per 1-mm brine shrimp according to Tong et al., 2000, Table 2.
- ^
Around 10^-7 grams per individual based on Bar-On, Phillips & Milo, 2018, Table S1, with 0.02 gigatonnes of nematode carbon and 10^21 nematodes, and assuming nematodes are 15% carbon by weight. “0.04–7.34 µg per individual” for macrobenthic nematodes according to Sharma et al., 2011, which may be larger than typical.
Thanks, Michael! For readers’ reference, I have also estimated the scale of the welfare of various animal populations[1]:
I think it makes sense that Open Philanthropy prioritises chickens, fish and shrimp, as these are the 3 populations of farmed animals with the most suffering according to the above (1.74, 1.52 and 1.05 as much suffering as the happiness of all humans).
ETHU in the header of the last column means expected total hedonistic utility.
Ah, I definitely saw your post before, but it looks like I forgot about it. Thanks for the reminder.
(I started building the table here for another piece that uses it, and decided to spin off a separate piece with the table. That next post should be up in the next few days.)
I guess I’ll add humans for comparison, like you.
Executive summary: The number of farmed animals, especially small animals like fish, shrimp, and insect larvae, is extremely large and raises questions about the scale of animal welfare considerations in agriculture.
Key points:
Estimates suggest there are over 2 trillion farmed vertebrate animals alive at any given time, with over 500 trillion killed per year.
Farmed shrimp, fish, and insect larvae vastly outnumber farmed mammals and birds.
Brine shrimp nauplii, with 1.5 trillion alive at a time and 540 trillion killed per year, challenge expected value reasoning and moral aggregation due to their small size and uncertain sentience.
Further research on the mental capacities of small farmed animals like shrimp and insect larvae could be valuable for assessing their moral weight.
The scale of animal farming, especially of small animals, raises important questions about the magnitude of animal welfare considerations in agriculture.
This comment was auto-generated by the EA Forum Team. Feel free to point out issues with this summary by replying to the comment, and contact us if you have feedback.
Executive summary: The number of farmed animals, especially small animals like fish, shrimp, and insect larvae, is extremely large and raises questions about the scale of animal welfare considerations in agriculture.
Key points:
Estimates suggest there are over 2 trillion farmed vertebrate animals alive at any given time, with over 500 trillion killed per year.
Farmed shrimp, fish, and insect larvae vastly outnumber farmed mammals and birds.
Brine shrimp nauplii, with 1.5 trillion alive at a time and 540 trillion killed per year, challenge expected value reasoning and moral aggregation due to their small size and uncertain sentience.
Further research on the mental capacities of small farmed animals like shrimp and insect larvae could be valuable for assessing their moral weight.
The scale of animal farming, especially of small animals, raises important questions about the magnitude of animal welfare considerations in agriculture.
This comment was auto-generated by the EA Forum Team. Feel free to point out issues with this summary by replying to the comment, and contact us if you have feedback.