Given the fact that their whole culture was the twirling hippie, peace, drugs, vegan thing, which members adhered to that concept as well?
The “hippies” were not a monolithic culture.
Some were into no drugs–some into all of them. Most of them liked one or two.
Back then, vegans were rare. Vegetarians weren’t. But quite a few “hippies” would eat anything they could afford.
Considering that one of the well-known communes of the day, near San Francisco, was the Hog Farm commune I don’t think that there was any particular correlation between hippies, however you define them, and vegetarianism. Granted there were probably quite a few more vegetarians among the counterculture population than elsewhere, they still weren’t so prevalent that you could assume that any member of a band would be vegetarian.
Nor should anyone think that vegetarianism originated with the 1960s counterculture. This picture of early 1900s Los Angeles shows a vegetarian restaurant on the right (scroll about halfway down).
Bob Weir is a vegetarian, as was Jerry Garcia. So is Phil Lesh.
All good points. I should have been more specific. I meant by today’s standards. I actually know quite a few “hippies” by today’s standards from following Phish around when they were still touring and together. I actually played in a jamband. Getting to know these people, a LOT of them are now vegetarian and some full blown vegan. If I had to guess, I’d say 45% of the “hippie” crowd nowadays are vegetarian.
Hell, if you go to a jamband festival nowadays, you’ll see “phatty veggie burito” stands, soy grilled cheese, soy burger stands, soy this and soy that. A LARGE majority of them are veggies.
So, I was wondering about my OP. So, thanks guys ! 
Peace, man ! lol
Well, I’ve been called a hippie by several people (both friend and stranger) so I nominate myself as an expert. I’m a meat eater. But I also eat soy products. I like the taste of soymilk. I would agree that there is likely more vegans in a hippie environment than in a regular environment, but I don’t know if I’d put the number as high as 45%. All the "hippies’ I know eat and love meat. Mmmm cowflesh.
As one of Jerry’s favorite dishes was a chili dog and an egg cream, I’d say he came to vegitarianism too late.
Garcia denied being a hippie at one point, IIRC.