A lamb is born with all the muscle fibers it will ever have, feeding or exercising will not make a lamb into something it is not genetically capable of being. Usually, lambs should be from average to large in frame size, for their breed, for economical gains. Very small and very large frame size lambs should be avoided, as they often finish at weights that are not market acceptable. Frame size is often thought of as just height, when actually it includes body length and body capacity. Frame size can be compared to a rectangular box, with height, length and total volume all making an equal contribution.
Structural correctness refers to several traits.
Certainly, your lambs should have sound mouths, normal eyes, and be free of any abnormalities. Feet and leg placement should be square with normal width and straightness. Furthermore, lambs should have strong pasterns and no feet problems. Do not buy lambs that limp and if a producer has footrot problems in his flock, consider buying from someone else. Balance or eye appeal is also desirable in your lambs.