I feed alfalfa and grain to my pregnant does. I start out with a smaller amount of grain(about a 1/4 pound or one cup, but I have small goats), then double or triple that the last month of pregnancy depending on the goats condition and how big they look. Then I give them as much grain as they want while I'm milking them. The pound for pound is a good general rule, but some of mine don't want to eat that much. I also give free choice grass hay and a flake or two of alfalfa hay for my 4 girls to share every day. As far as minerals, if they are zinc deficient you can give the 50 mg zinc tabs for humans. You can get them very cheaply at Walmart or your local pharmacy. I give those in their grain and they don't notice. The signs of zinc deficiency are hair loss around the eyes and lots of flaky skin. I gave those tablets once daily for a full week and then once weekly after that when I saw some flaky skin and hair loss and it was all cleared up in less than a month. I also give extra selenium during pregnancy, once a month. I use the gel and sandwich it between animal crackers. You can also use the injection, BoSe which you can get from your vet. Make sure they are getting a high quality free choice loose mineral, meaning they always have access to it. And I would only offer baking soda if you suspect bloat. You can also give them some kelp for an extra vitamin and mineral boost, though kelp is a bit pricy. I only usually give kelp before breeding and during the last month of pregnancy.