Hmm. I think it would have to be powdered, otherwise it would like asking your goats to eat tiny rocks. I use powdered dolomite, because it contains the proper balance of calcium, magnesium, and phosphorous. Alfalfa and comfrey are good plant sources of calcium.
I would use something specific to goats. Mine do eat the chickens oyster shells but it hurts their throat and they cough a lot for days after. Coughing can do a lot of harm to a goat.
I was just sitting here thinking to myself what is possible for calcium supplements and since we have chickens anyway was thinking of doing some research into the possibility of this a supplement depending on it's form.
However it being an animal by-product I wasn't sure how well that work.
Causing the goat to cough is most definitely a no no.
Oyster shells are as rare as hen's teeth on the coast this year. We haven't been able to get any since last summer. They are waiting for the next oyster harvest before they can get more, but the demand is so high, there won't be much and the price will be way too high.
We've been using this crushed lime stuff the feed store recomends. The hens hate it.