The phrase "fed grass" means that something or someone has eaten or consumed grass.
Sentences with «fed grass»
Another important benefit of feeding the grass hay to the exclusion of other foods initially is that your pet will experience a healthy weight loss. (vin.com)
Their dairy farm is certified organic and the cows are fed an all grass diet as opposed to supplementing with grain. (emilystastyadventures.com)
When an animal protein is classified as grass fed, that means that the animal was only fed grass. (mindbodyoasis.com)