Hi Declan
Depends perhaps on why they became bottle fed and whether or not they were given enough colostrum immediately after birth - without that they are likely to suffer from more illnesses than lambs reared by their dams and there appears to be an increased risk of sudden death in the first few months. I would be doubtful about breeding from orphan lambs - if the dam died then it could have been from something hereditary such as a narrow pelvis (leading to a problem lambing) or weak blood vessels. As with dogs, horses etc, it's better to see the parents before choosing breeding stock. If they are as pets or for meat, less of a problem.