There’s was a chap I use to knock about with a few years ago always use to tell me to give a bitch a pint of full cream cows milk everyday once she has whelped to help her keep good weight and plenty of milk flowing from the bitch. That along with plenty of good grub is about all you can do. right or wrong it seems to work and the bitch goes mad for it, the mans dogs were always in great fettle at all times he kept some of the best looking dogs condition wise I have seen.