The Bagpipe - American Highland Cattle Association

4
GENETICS AND SELECTION
STRUCTURAL CORRECTNESS
IN BEEF CATTLE
Harlan Ritchie, Ph.D. & Peter Anderson, Ph.D.
Introduction
A minimum degree of structural correctness is needed in all species of animals. However, it assumes greater
importance in some classes of livestock than in others. For example, it is of utmost importance in the horse because its
activity (racing, working cattle, draft, etc.) generally places a greater degree of stress on the skeleton than is the case
with other species. In beef cattle, structural correctness is of greater importance in the bull for several reasons: (1) he
is heavier than the female; (2) in range country, he must travel relatively long distances to cover cows in heat; (3) he
transmits his structural traits to his daughters who will eventually become herd replacements (unless he is in a
terminal sire breeding program). Structural correctness is also important in the female for several reasons: (1) it
contributes to longevity, a trait which recent research at Montana and MARC (Kress et al., 1988) has shown to be highly
related to cow herd efficiency; (2) working on cows with structural problems is costly in terms of time and money; (3)
unsound cows transmit problems to their progeny just like bulls, although they obviously do not have the impact on the
herd that a heavily used sire does.
Structural soundness is not an all-or-none proposition. These traits usually occur in varying degrees from slight to
severe. In most traits, there is a “range of acceptability” within which the animal can function efficiently. Furthermore,
some structural defects are more apt to impair function than are others. Developing a feel for this range of acceptability,
as well as knowing which defects are most serious, is something that livestock breeders and judges should strive for. A
common mistake made by some beginning judges is to overreact and place too much emphasis on relatively minor faults
in structure. It should be remembered that beef cattle are raised to produce meat, not to compete at the race track with
the Thoroughbred! Conversely, overlooking serious defects in structure is just as much a problem.
Most structural defects are heritable to some degree and should be particularly discriminated against in maternal
and general purpose breed bulls whose daughters will be kept for replacements. On the other hand, certain problems
can be tolerated in bulls of terminal sire breeds if they do not affect longevity or the ability to mate.
The purpose of this paper is to characterize the structural problems that are most commonly encountered in beef
production and to discuss their importance and relationship with function. The World Simmental Federation (WSF) has
developed ranges of acceptability for a number of structural traits. Although their guidelines may not be totally
applicable to all breeds in all environments, they will be referred to in this paper because they represent a conscientious
and united effort on the part of a large association of breeders to address the subject of structural correctness.
Skeletal Structure
In order to consider correct structure, one should be familiar with the bovine skeleton. The drawing on the following
page lists the primary bones and joints that are implicated in structural soundness, including their Latin and common
names. A discussion of skeletal structure will be presented in the sections to follow.
Feet and Pasterns
In general, the feet and pasterns of a sound animal should exhibit the following characteristics:
1. Normal rate of hoof growth.
2. Adequate size (area) of foot.
3. Even-sized claws (toes).
4. Toes held together and not spread.
5. Adequate depth of heel.
6. Correct slope to pastern and foot as viewed from the side.
7. Relatively straight as viewed from the front.
8. Hard, dense hoof.
Defects of the feet and pastern are covered in the following sections.