Feed-food competition

We could easily meet all extra food needs from a growing population even out to 2050 if we just ate more of the crops we feed to animals (Berners-Lee, Watson and Hewitt 2018)
in 2007, 25% of fish were fed to farm animals Erb et al., 2012
Cassidy et al., 2013 argue that if we stopped using crops for feeding animals and simply fed those crops to humans, we could feed an additional 4 billion people and increase calories available to humanity by 70%
At global level, human-edible feed materials represented about 14% of the global livestock feed ration. Grains made up only 13% of the ration, but represented 32% of global grain production in 2010 Mottet et al., 2017
In the EU and U.S. around two-thirds of cereals are used as animal feed. Globally the figure is 40%
Shepon, Eshel, Noor and Milo, 2018 found that if the US replaced their animal products with plant-based replacements for each of the major animal categories in the United States (beef, pork, dairy, poultry, and eggs) can produce 2 to 20 x more nutritionally similar food per unit cropland.
20% of soy is eaten by humans, mostly in soybean oil. tofu and soy milk are just 7%. 77% is fed to livestock (Ritchie, 2021)
- Over one-third (37%) of global soy is fed to chickens and other poultry; one-fifth to pigs; and 6% for aquaculture. Very little soy is used for beef and dairy production – only 2%.

Sub-Saharan Africa is already a net importer of grains Erb et al., 2012, almost all of which are for human consumption so increasing animal production is likely to increase imports and increase food-feed competition. See also International trade in animal products and feed

Note that the % of agri land that goes to towards feed is actually lower than in the 70s: https://www.ocl-journal.org/articles/ocl/full_html/2014/04/ocl140020/ocl140020.html

Also applies to fish: https://onlinelibrary.wiley.com/doi/10.1111/raq.12804