Salatin's system is a little more complex than that...yeah, the herd of X number of
cattle graze and mob down the grass for a day out of a hundred, but then the get followed by the pigs and chickens...I don't know all the details but yeah...
There is no pat
answer to your question, there are too many variables, but I would recommend some experiments...take x number of goats, and put them on x cubic (yes cubic) feet of browse...you figure the cubic by the avrrage height of goat nose when they reach up, photograph the foliage in a sample of that area, let the goats browse it down, recording the amount of foliage loss over x number of days, then move the herd on to another paddock...now do it all again in reverse...record photographically the recovery of hte foliage, and that number of days of recovery towards the original, or selected optimal foliage density will give you a rough figure based on number by type of goat, figured by cubic of foiage, for x number of days under similar weather conditions....
Then come back and tell me how went...lol!