Is the 7 week old calf able to suckle the cow or are you milking the cow and bottle feeding the calf? When I raised Belgian Blues, I had much better luck with the calf when I gave the cow MuSe and then fed the calf her milk. I am not a vet, but I believe the selenium is more bioavailable to the calf this way. It seemed to save a couple of calves with white muscle disease when the shots of MuSe never seemed to work. Hopefully the calf is doing okay and this helps.