With sheep that age we bottle feed about 6 oz 5 times a day... gradually increasing the amount at the feeding, and decreasing the number of feedings. They usually drink more first thing in the morning and less at later feedings.
Edit: That’s with straight bottle babies... it’s good that mama went 3 weeks, they got the colostrum and lots of antibodies from her at first. Watch her closely for mastitis!
I was a little confusing there... over the course of several weeks as they transition to grass and hay and develop we increase the amount and decrease the feedings... (I re-read my post and realized it sounded like we increase the amount every feeding, which we don’t!)