0 The edge of the keel is rough, sharp, and prominent. Very little breast muscle can be felt, and the breast on either side of the keel feels hollow or concave. This bird is very thin.
1 The keel is prominent, but doesn't feel sharp. There is some breast muscle, and the breast on either side of the keel feels flat. This bird is thin.
2 The keel is less prominent, and the edge is smoother. The breast muscle is well developed. The breast on either side of the keel is rounded or convex. This bird is in good condition.
3 The keel feels smooth and not very prominent. Feeling the edge of the keel may be difficult through the plump, rounded breast muscles. This is a fat bird.