Feeding our dams in such a way that they are supported in rearing healthy puppies is of key importance to us at Sunnyside. As well, making sure she's intaking enough liquids to produce plenty of milk enables her to care properly for her pups.
As with our whelping pen post, mine is not the "only" way ;) And I'll be the first to say that learning is life long, so there will likely be changes, additions, deletions to my concepts as we experience more. Many people feed raw. It's not something everyone can do. We try to take a middle ground approach. We offer our postpartum moms broth water to drink. This is highly nutritious and the delicious taste encourages her to drink plenty.
To make the broth, we use a 16 quart stock pot to which we add beef, chicken and liver (pieces or ground). If we have bones, we add those, too. We add water, and boil until everything is cooked through and, if using bones, they're softened). We then remove any bones and use a hand blender to chop everything up into little bits.
A couple of large soup ladles of the broth concentrate is added to the water dish several times / day and more water is added to it. Occasionally, we'll add formula (discussed in more detail below) to the water, too, just to make sure dam is getting an adequate Calcium intake. We further use this broth for pouring directly on top of the kibble we feed to moisten it (which keeps dry kibble from dehydrating dam in addition to increasing palatability).
Mmmm, doesn't that look yummy?! lol :p
(The dams like it, anyway!)
In regards to the kibble we feed, we use Dog Food Advisor to give us a list of possible foods. Then we go to our local pet store and see what on that list is actually available here. Different areas of the country have different options, so I'm not going to promote a particular brand here. Just choose one that is the best you can afford that your dogs will eat. If there's more than one option, I bring home sample sizes, place them in bowls, then let the dog pick which one she prefers. Beyond the basic high quality food expectations as laid out on DFA (like quality protein being the first ingredient on the list, and no corn added), two elements that we require of any food is that it break down in cool liquid and that it smell decent. If we have to cook it and use a blender to try to bust up the rocks, or if it stinks when wet, it's a deal breaker regardless of the brand.
And if you want a simple way to add more protein to your dam's food, cat food is always a hit. Grain free is a big thing to many people, and for dogs with allergies, it is something to be aware of. On the farm, however, it doesn't make a lot of sense for us to pay extra for grain free, because the dogs simply help themselves to the grain in the barnyard, lol.
In addition to adding broth to the kibble, we make up Myra Savant-Harris's puppy formula... for the dam. (Myra is a wealth of knowledge on breeding and puppy care). Please note, we use 300 ml full fat goat milk since we can't get powdered or concentrated goat milk here. If I'm unable to get a full fat plain yogurt, I mix something like Balkan yogurt (6% fat) with 14% sour cream to boost the fat content.
During whelping we offer the formula straight to the dam for the needed Calcium, along with raw pieces of liver to give energy. Afterwards, we pour the formula over her kibble to boost both nutrition and taste. Although it's not as critical a supplement postpartum as it is prior to birth, I like to try to include some MegaC powder in the dam's formula now & then, just to support her own joints in the post birth recovery period. Pups are daily given their own liquid version of the same supplement, which is why it's not as crucial for the pups that it be in the dam's diet once pregnancy is over. Breeders I know who have supplemented their dogs with these items have had very good resultant hip scores. It's not a guarantee, of course, but we're doing our best to give the best chance for good hips.
At one point we had a dam with a litter of 15 pups. We supplemented pups that needed it (while leaving them on dam) with the formula a couple of times per day, while feeding these items to the dam. That dam actually had noticeable weight gain while nursing and caring for 15 pups. Of note, all the pups love it, we had no runts and the vet was astonished at how big and uniformly sized the entire litter was. As a result of this, and other breeders' positive experiences when raising orphaned or abandoned pups on this formula, I highly recommend this formula for anything from supplementation to exclusive bottle feeding of pups.