There have been quantitative calculations for antibiotics taught for years in ag departments, and known among industry practitioners. Farming is a highly quantitative industry, and any agent of growth promotion is tracked carefully along with feed energy & cost inputs. Today you may have to go back to older documents to see talk about it in a more open manner though.

Here's a more industrial type of analysis paper (2003)

https://www.cambridge.org/core/journals/journal-of-agricultu...