What to feed Nigerian does that need to gain a little weight?

[makingshift]

Hello, all! It has been a while since I posted here. My two Nigerian does just turned one year old and they just came home from two weeks at the breeders'. (First time being bred.) The breeder thinks they look a little thin and need to gain a little weight. I think she is right. They've been really healthy, happy goats but they are slightly thin and on the smaller side. Here is my usual feeding regimen:

free-choice coastal hay (here in Central TX my only options are coastal and alfalfa)
1/2 cup sweet goat feed per day per doe
free-choice loose mineral
free-choice baking soda
plenty of fresh water, of course

They are on dry lot and I don't have fenced pasture to put them out on. I do bring them cuttings from trees and bushes a couple of times per week (being careful to avoid anything poisonous).

So I am wondering what I need to change about my feeding regimen to help them gain some weight, especially since are both probably pregnant now. I would imagine I could give them some additional grain but I'm also wondering if they could use some alfalfa pellets (or alfalfa hay) or even some BOSS. (I'm planning on feeding BOSS at the end of pregnancy and during lactation).

Thanks in advance!

 

[OneFineAcre]

Would love to see some pics
You could do any of the above I would lean more towards alfalfa hay in that has seemed to work for me
You should probably get a fecal to see if they have any worm load but being dry lot probably not an issue
Would be cautious in making to much of a change though and to fast
You don't want them to gain too much while pregnant in that can lead to problems as well