We have had 3 litters since 2007. The first litter we had 7 & lost 2. The second litter we had only 1 but he made it. We just had a litter 10 days ago and she had 8. 5 boys & 3 girls. We lost 2 in the first 3 days, 1 boy & 1 girl. So it really depends. I think it is different for each litter and depends and the female & male you bred as to the number of puppies you will have and also the care that is provided during pregnancy and after. Just know you really have to watch them in the first few days very closely. It's a good idea to have puppy replacement milk & a puppy nursing bottle on hand just in case.
I would try to feed the dame beef livers cooked and chopped with some water and dry dog food 3 times a week during her 60 day birth cycle. Also, give them a daily vitamin chewable. My Dame had 7 pups; 5 male and 2 female. One of the females is the runt of the litter, so I make sure she is getting plenty of nursing alone with mom. Also, since it's been getting cold I use a heating pad on low to keep them warm and comfortable. It's really important to keep the bedding changed twice a day. Also, try Condensed Goat Milk at warm room temperature and give the puppies a tablespoon 2 or 3 times a day during the third week. My pups are nearly 4 weeks old and the Dame seems to be pleased that I'm helping her feed them.