If you're selecting the bull on the basis of it's own body production, you look for muscularity and size.
For breeding purpose, most producers prefer selecting the bull on the basis of the quality of its progeny (babies). If the babies have good build, and have higher feed conversion ratio (more weight gain by eating less), then we can be pretty sure about selecting the father.basically the body conformation of a good beef type cattle is:
Apart from this be sure to-
- heavy build and large size
- less fatty and more lean
- thick neck
- fleshy shoulders and thighs
- broad rump
- wide chest, with good fleshing
- the fore legs, when observed together from the front, should be straight and a little apart (unlike milking animals, who should have an angular pose, with the legs narrowing near the bottom)
- the physical condition sholud be good. The eyes bright and lively, active disposition of the animal. we don't want a lazy animal who tends to accumulate fat.
- check the breeding efficiency by going through the records.
- selection on the basis of body conformation alone is not preferable, support it with the performance of the bull's babies, or the bulls parents, or the bulls brothers-sisters (selection on the basis of family).