I eat a lot of butter. It is my primary cooking fat, I'll often drink butter tea for breakfast (~4 TBSP of butter with herbal or green tea, riffing off of Tibetan tea), and sometimes I'll just eat a few pats or feed a few pats to my kids when they're starving and dinner isn't quite ready. I believe butter can be a very high quality food, and I feel great eating lots of it.
I want to eat butter that is exclusively, or at least primarily, made from cows eating grass; not grain. I asked the producers of several types of butter available in my local market what percentage of their cows' diet was grass. Here are their responses:
Cows are grass-fed on pasture whenever possible, but feed can vary given conditions. They are also fed alfalfa and grain.
From website: "The vast majority of an Irish cow’s diet is from rich, natural grass which grows abundantly in Ireland. Irish dairy cows graze outdoors on grass all day long for up to 312 days a year ... During the winter, when grasses stop growing, Irish cows are fed dried grass (known as silage) ... After calving, cows are provided with supplementary feed to help restore protein and nurture them through this period ... The majority of our cows’ supplementary feed is locally grown crops such as wheat and barley."
Cows are primarily grass-fed on pasture, but they do receive supplemental feedings of grain.
Sierra Nevada Cheese Company
Cows are not exclusively grass-fed; they are also fed grain.
Straus Family Creamery
Our cows are pasture-fed and are certified organic. Whenever the weather permits, they spend their time out on pasture, grazing on the rich, sweet grasses that are typical for Marin and Sonoma Counties in Northern California. Their diet consists of about 75-80% forages, which include fresh grasses, silage and hay. The other 20-25% consists of a variety of certified organic grains.