How much protein could ruminants produce without crops?

Explore this scenario: Suppose that nobody uses any crops as animal feed. Not even crop residues(...)( because those could be used for growing mushrooms instead ). But that farmers still raise cows/sheep/goats on pasture. Fewer of them, overall(...)( the lower populations can be achieved gradually by farmers choosing to not breeding as many. No need to envision a massive culling ).

How much animal protein (from meat & milk) could this produce?

• For scale, express it in terms of meat & milk per day, per capita, globally.

Consensus

This section can stay blank for quite awhile, until enough answers come in.

Answers

Elie (talk) 14:12, 15 November 2024 (EST)

7.2 grams of protein per day, per capita, worldwide, in total from both meat and milk combined, from all ruminants (cows, sheep, goats, buffalo, etc).

pasture

2.8 billion tonnes/year

Dry mass of all grass & leaves, grazed from all pasture land

Source:

Breewood, H. & Garnett, T. (2020). What is feed-food competition? (Foodsource: building blocks). Food Climate Research Network, University of Oxford.
Page 10
References primary source:
Mottet, A., de Haan, C., Falcucci, A., Tempio, G., Opio, C., & Gerber, P. (2017). Livestock: On our plates or eating at our table? A new analysis of the feed/food debate. Global Food Security.

conversion_ratio

1 / 133

Ruminants produce 1 gram of human-edible protein for every 133 grams of dry matter they eat.

Dry matter includes all materials eaten by ruminants (both human-edible and human-inedible).

Source:
Mottet, A., de Haan, C., Falcucci, A., Tempio, G., Opio, C., & Gerber, P. (2017). Livestock: On our plates or eating at our table? A new analysis of the feed/food debate. Global Food Security.
The number is mentioned in the Abstract: https://www.tabledebates.org/research-library/livestock-our-plates-or-eating-our-table

world.population

8 billion

pasture * conversion_ratio / world.population g/day per capita (calculation loading) Note: Ways this result could vary slightly: (...)(  ~ Feed conversion ratios might be lower without corn grain - in which case, the result would be lower. ~ But if farmers focused more on milk than meat, they might be able to get the feed conversion ratios up a bit. )

For comparison:
The status quo is 16 grams of protein: 10g protein from 297mL of whole milk; 6g protein from 30g of meats. (Status quo numbers are from Code:food2.sql)

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