My phD project aims to study the passage of different antibiotics in the milk of various species. The 4 antibiotics chosen belong to different families and represent a large sample of physico-chemical properties such as lipophily, chemical structure or pharmacokinetic parameters. Their passage into milk is studied in cows, goats and ewe, major milk producing species. The goal is to create a Physiologically Based Pharmacokinetic (PBPK) model taking into account antibiotics properties and physiological characteristics of the species. This model will have to describe the evolution of antibiotics in the milk. In the longer term, the PBPK model will allow us to predict the passage in the milk of various xenobobiotics as other medicines or environmental contaminants in farm animals as well as in the woman.