Addressing the 2050 demand for terrestrial animal source food.

The high emissions intensity of terrestrial animal source food (TASF) and projected increasing demand in low- and middle-income countries (LMIC) have spurred interest in the development of animal-free alternatives and manufactured food items that aim to substitute for meat, milk, and eggs with the promise of reduced environmental impact of producing food. The developing world is the source of 75% of global emissions from ruminants and will house 86% of the world's human population by 2050. The adoption of cost-effective, genetic, feed and nutrition practices, and improving livestock health in LMIC are seen as the most promising interventions to reduce emissions resulting from projected increased TASF demand though 2050. Genetic improvement is a particularly attractive approach to productivity enhancements, as such improvements are permanent and cumulative. Alternative proteins may play a role in addressing demand for affordable sources of nutrient-dense foods, however, price will be a major factor influencing adoption given 3.1 billion people globally (42%) were currently unable to afford a healthy diet in 2021. Additionally, there is currently a mismatch between the location of alternative protein companies, and both projected increased TASF demand and emissions. To date, the vast majority (>81%) of these companies are based in high-income countries. The sustainability implications of replacing TASF with alternative proteins at scale needs to consider not only environmental metrics but also the wider economic and social sustainability impacts, given the essential role that livestock play in the livelihoods and food security of approximately 1.3 billion people.