https://www.academia.edu/34671069/On_the_hoof_exploring_the_supply_of_animals_to_the_Roman_legionary_fortress_at_Caerleon_using_strontium_87_Sr_86_Sr_isotope_analysis?auto=download&campaign=weekly_digest
a really quite detailed treatise on a specific locale during the Roman period and the supply of animals and provisions thereof...
The piece takes a lot of effort to say that the builders brought animals with them and thereafter the garrison fed off local animals. Still, it helps to confirm that local provisioning seems to have been the norm.
its the application of hard science to back up what was a reasonably obvious premise