This editorial discusses the use of alternative and novel livestock feeds to reduce environmental impact. Livestock production systems are responsible for 14.5% of anthropogenic greenhouse gas (GHG) emissions, mainly from enteric fermentation. Feed accounts for 55%–75% of the climate change impact. Cultivation, processing, transport, and land-use change are the main sources of GHG emissions from animal feed production. Enteric methane emissions from ruminants and monogastric animals significantly contribute to the environmental footprint of agriculture. Methane and ammonia emissions also represent a significant loss of feed energy. Alternative feeds and additives could improve total digestibility and have significant potential to improve animal performance and reduce emissions. However, the feasibility of using alternative feeds depends on the nutritional value of novel ingredients, animal production responses, and feed costs compared to conventional feeds. In this Research Topic, 17 research articles and 1 review were collected on the use of alternative feeds in animal nutrition. The articles cover alternative feeds in ruminants and pigs, and in poultry. The studies show that alternative feeds can improve animal health and performance, and reduce environmental impact. However, further studies are needed to find the right dose to include these feeds in animal diets to avoid a reduction in degradability and adverse effects on animal performance compared to conventional feeds. The authors conclude that alternative feeds and additives could be a useful tool to reduce the environmental impact of livestock animals without adverse effects on animal performance and products.This editorial discusses the use of alternative and novel livestock feeds to reduce environmental impact. Livestock production systems are responsible for 14.5% of anthropogenic greenhouse gas (GHG) emissions, mainly from enteric fermentation. Feed accounts for 55%–75% of the climate change impact. Cultivation, processing, transport, and land-use change are the main sources of GHG emissions from animal feed production. Enteric methane emissions from ruminants and monogastric animals significantly contribute to the environmental footprint of agriculture. Methane and ammonia emissions also represent a significant loss of feed energy. Alternative feeds and additives could improve total digestibility and have significant potential to improve animal performance and reduce emissions. However, the feasibility of using alternative feeds depends on the nutritional value of novel ingredients, animal production responses, and feed costs compared to conventional feeds. In this Research Topic, 17 research articles and 1 review were collected on the use of alternative feeds in animal nutrition. The articles cover alternative feeds in ruminants and pigs, and in poultry. The studies show that alternative feeds can improve animal health and performance, and reduce environmental impact. However, further studies are needed to find the right dose to include these feeds in animal diets to avoid a reduction in degradability and adverse effects on animal performance compared to conventional feeds. The authors conclude that alternative feeds and additives could be a useful tool to reduce the environmental impact of livestock animals without adverse effects on animal performance and products.