Definitely effects humans. I was nursing my daughter and my nephew and then he stopped nursing and whammo, mastitis. VERY painful. When a baby is first born and NEVER nurses, it helps to slow down the production of milk, in fact in the beginning it is not milk at all, but colostrum in all mammals. It gives them needed antibodies. Most likely the baby rats, unless pulled as delivered, did nurse some, got the colostrum, then it kick started the mom into making milk. I always pull my litters down to 12, then if I need more only take five more, then another five, then the rest, with a few days in between. Vigorous nursers can also increase the milk production in a female.
*Fila*