The USDA is currently developing guidelines to define the term “grass-fed”, and it is expected to call for an all-grass diet of at least 95%. Strictly grass-fed cattle tend to be leaner than grain-fed.
The USDA is currently creating guidelines for cattle that eat only plants, and it is expected to call for an all-plant diet of at least 95%. Grass-fed cattle tend to be leaner than those that also receive grains.