Frame and Muscle
USDA Feeder Calf Grades are based on frame and muscle scores. Frame and muscle
are highly heritable, and they both have a major effect on feeder calf prices. Frame and muscle in the bull should
be matched with that of the cow herd to produce calves that will be acceptable in the marketplace and replacements
that will perform in the herd's environment.
Frame size provides an estimate of rate of maturity, mature size and carcass cutability
at a given live weight. Frame size is generally appraised visually by bull buyers or measured in terms of hip
height adjusted to a standard age. Some breeders provide adjusted hip heights or frame scores on their sale bulls.
Larger framed steers gain more efficiently and are leaner than smaller framed steers at a given weight. Packing
plants discriminate against carcasses that are too light or too heavy. For these reasons, feeder calves that are at
the upper end of USDA Medium or the lower side of USDA Large generally bring the best prices. While larger framed
market animals may be preferred, larger framed females in the herd may reach sexual maturity later and require more
feed for maintenance. Increasing frame size in the cow herd without increasing the level of nutrition will
generally result in a decline in reproductive efficiency.
Adequate muscling is usually determined by visual appraisal. Feeder calves that are not
thick enough to grade USDA Number 1 muscle are generally discounted heavily. While light?muscled bulls can affect
the marketability of calves and carcass cutability, extreme heavy muscling may be associated with structural and
reproduction problems. Evaluate the cow herd and determine the amount of muscling required before selecting a
Some breeds are developing carcass EPDs. However, these are not generally available on
most yearling and two year old bulls. As more carcass data are collected, these EPDs will become more
Any consideration of a bull's potential genetic contribution to a herd is
meaningless if he is not structurally sound and physically fit to seek out cows in heat and service them.
Structural soundness is not an all-or-none trait. It usually occurs in various degrees. Bad feet, pigeon toes,
straight hocks and loose sheaths are examples of some of the more common structural problems. It is especially
important to critically evaluate young bulls since these problems tend to get worse as bulls get older and heavier.
Structural soundness in bulls is best evaluated from the ground up. Inspect the bull's feet, toes, heels, pasterns,
knees, hocks, sheath and testicles and study his movement carefully to see that he moves freely and strikes the
ground evenly with each hoof.
Many structural problems are heritable and should be particularly discriminated against
in bulls whose daughters will be kept for replacements. Minor structural problems can be tolerated in a terminal
sire, as long as they do not affect his longevity or ability to service cows. The tolerance level for structural
problems should be determined beforehand, not while looking at prospective herd bulls.
Visually evaluating a bull for structural soundness also affords an excellent
opportunity to evaluate disposition or temperament. Disposition is heritable. A bull with a poor disposition not
only causes problems himself, he also produces daughters that can make the cow herd more difficult to work.
A good prediction of bull fertility can be made by a complete breeding soundness
exam that includes a semen test, scrotal measurement, and a physical examination of the reproductive tract.
Commercial bull buyers should not hesitate to ask seedstock breeders for a breeding soundness examination on all
prospective herd bulls.
Although the importance of producing viable semen in ample quantities is obvious, semen
evaluation of yearling bulls (12 to 15 months of age) can be misinterpreted. Certainly the production of live sperm
cells is meaningful, but failure to produce good semen at the first collection of a yearling bull is not
conclusive. Young bulls should be rechecked after a few days rest (or weeks if they are less than 13 months old).
Often they will produce acceptable semen when rechecked. Normal extension of the penis (free of adhesions) and
absence of pus in the ejaculate are positive, meaningful observations, which by themselves are sufficient reasons
to semen check young bulls.