My puppies have access to their mom's food... a high quality commercial puppy kibble (Royal Canin)... from the time they can get in it, which is usually around 3 weeks. They start eating it... dry, right out of the bowl... almost immediately and by the time they are 5-6 weeks, when most people are "weaning" their litters, mine are pretty much on solid food period. Knock on wood, I have never had a mom want her pups to leave her alone because her nipples are sore from their teeth. (My pups have kibble to chew on and seldom do anything but SUCK on their moms.) And moms don't lose weight from nursing too long. In fact, I usually have the opposite problem... moms fatter than they need to be because they are still eating the puppy food. When my pups leave at 12 weeks and beyond, their moms are still in with them much of the time, by choice. It is so amazing to watch the interaction of mamas and "older" babies. Both benefit from it.