According to the organic promoter, cows, chickens and pigs now eat less grass and food waste than 60 years ago, and more grains and imported proteins. It says this is highly inefficient, and also makes food systems more vulnerable.
The report, called Feeding the animals that feed us, points out that the demand for meat and milk is putting pressure on rainforests and grasslands, as there is demand to switch turn them over to agricultural use.
“Farm animals can play an important role in helping to tackle environmental challenges - helping us store carbon in grassland soils, recycling our waste food, providing nutrients to grow our crops, and giving us healthy food to eat,” says the Soil Association.
The Soil Association report is available here http://www.soilassociation.org/Whyorganic/Climatefriendlyfoodandfarming/Sustainableanimalfeed/tabid/1183/Default.aspx