"en sevrage" means the period he is being weaned; in general if it doesn't drink milk anymore, they are called "sevrés", and they go in "post-sevrage", specially for the pigs.
A baby still drinking milk is called "under the mother", veau sous la mère; or for piglets:"cochon de lait".
So what does "starter" mean exactly?
"Starter" remembers me the food I used to give to piglets.