The cow with her working clothes on — that's what we all strive for in our cattle operations. Realizing the need to minimize production costs, cow-calf producers continue to place emphasis on cow function. Fortunately, as selection for functional traits becomes more important, technologies exist to allow producers to make better decisions on selecting a cow's lifelong functional traits.
“Length of productive life is probably the most important trait in cattle breeding,” says Dave Seibert, University of Illinois Extension animal systems educator. “The longer animals remain productive in a herd, the fewer replacements are needed.”
Thus, he says, the cost of growing replacements to productive age is reduced, and more of the operation's inventory can be in producing cows.
“Since the efficiency of the entire cow-calf system is highly dependent on the efficiency of the cow herd, each individual cow ultimately affects the system,” adds Jim Gibb, senior manager with Igenity.
Cow function may be defined in many ways, but Gibb says four fairly common definitions are cows that:
don't cost extra time and labor,
work for you instead of you working for them,
are problem-free, and
return a profit.
The major factors affecting longevity are infertility; structural unsoundness, including feet and legs; eye diseases; udder trouble; and teeth and mouth problems. These are the physical characteristics that can be seen and selected against.
Identifying prolific long-time producers through pedigrees and lifetime production records can enhance accuracy of selection for longevity.
“There's a certain amount of automatic selection for fertility and longevity,” Gibb explains. “Structurally correct and productive animals remain in the herd longer, and have a larger number of offspring saved for replacements.”
He lists some general consequences of functional problems that lower cow-herd efficiency. These include: lower cow and calf sale weight, high replacement rate, increased labor, increased death loss, inconvenience and reduced safety.
“The end result of these problems is increased costs and lower production, resulting in reduced net profit,” Gibb notes. “The ideal situation is to make improvements in these factors without added investment.”
Data from the National Animal Health Monitoring Systems (NAHMS) show functional traits account for more than two-thirds of cull decisions. Seibert and Gibb, along with Dave Kirkpatrick, University of Tennessee beef cattle specialist, list these important functional traits and their impact on cowherd efficiency:
- Structural soundness
Structural correctness is a subjective trait that can't be measured, but the rules of thumb include:
Evaluate structure from the ground up — starting at the hoof and moving higher.
Avoid cattle that are too straight — they don't have necessary flexibility or cushion in their joints.
Select cattle that “fill their track,” meaning when they move, they place their hind foot where their front foot has just been.
The point of the shoulder should form a 90° angle.
“Combining all the different parts of feet and leg soundness results in a term called angulation of the bone structure,” Seibert says. Animals with correct angulation will remain in the herd longer than those with too much angulation, like sickle-hocked cows, and/or not enough angulation like post-legged cows.
- Udder and teat conformation
“Udder and teat quality are two of the most important functional traits. Udder and teat characteristics appear to be moderately heritable,” Gibb explains. “The most appropriate time to evaluate a cow's udder is immediately after calving, when udder and teat problems are likely to create the most difficulty.”
An ideal udder is snugly attached, symmetrical and of moderate length. It features evenly balanced quarters with teats of medium size and length placed squarely under each quarter. A side view of the udders should show a level udder floor without any quartering.
- Frame score
Frame score has been one of the major driving forces in beef-cattle selection for the past 30 years. Initial work on frame score compared the growth rate, feed efficiency and body composition of three body types — small, medium and large. Frame scores can be a powerful descriptive tool when used to describe animals and to assist with the implementation of a frame window (5.0 to 7.9 range).
These measures reflect the ease with which animals respond to handling treatment and routine management. Iowa State University research shows wild, unmanageable cattle gain nearly Ω lb./day less in the feedlot than quieter, easily managed cattle — and return $61 less profit. Easily excited cattle produce more dark-cutter carcasses, which are heavily discounted.
“In addition, poor disposition — which is heritable — also has a negative impact on several economic traits,” Kirkpatrick says. “Among those are a delay in estrus onset, decreased milk production, less time at the feed bunk, poorer health status, reduced average daily gain and decreased meat quality.”
- Fleshing ability
Also termed “doing ability,” a measure of body fat, this is an evaluation of the adaptability of a female to a given set of resources.
“It can have a major impact on the animal's longevity,” Seibert says. “One of the best measures of fleshing ability is body-condition score (BCS).”
U.S. Meat Animal Research Center research found not all breeds need the same amount of condition to excel reproductively. Nine breeds were compared across the BCS range of 1-9 to identify the ideal for several traits with the most complete analysis based on pounds of calf weaned per cow exposed. The ideal BCS by breeds groups found Simmental and Gelbvieh at 4.8, Branvieh and Pinzguar at 5.0, Charolais and Limousin at 5.3, Red Poll at 5.4 and Angus and Hereford at 5.7.
“Fertile” females reach puberty at an early age, breed as first-calf heifers and calve earlier. The fertile female exhibits regularity of calving.
Attention should be given to reproductive genitalia, early udder development and general brood-cow features. Fertile, productive heifers tend to be slightly smoother in their muscle pattern than bulls or steers and shed their hair early in the season.
“Scrotal circumference in bulls is a trait used for years to improve the fertility of heifers by decreasing the age at puberty,” Gibb says. For every 1 cm. in scrotal circumference, research shows one can expect a decrease of 4-7 days in age at onset of puberty in heifer offspring. Also, the daughters of larger scrotal-circumference bulls should have a greater lifetime reproductive potential.
- Calving ease/mothering ability
Calving ease can be greatly increased by selecting herd sires that fall in the lower percentile EPD for birth weight or have above EPDs for calving ease direct. Pelvic measurement can also assist as an independent culling tool for heifers with small pelvic openings.
“A female with mothering ability will calve with more ease, and promptly get up and clean, nourish and protect the calf,” Kirkpatrick explains. “This female will also provide sufficient milk through weaning and have the ability to rebreed early.”
- Polledness, prolapse and cancer eye
Little needs to be said about the advantages of polled cattle. The polled gene is dominant to the horned gene.
“The heritability of prolapse potential has not been widely studied,” Gibb says, “but research shows certain cattle lines tend to have higher prolapse incidence. It suggests vaginal and uterine prolapse could be controlled to some degree by rigorous culling.”
The heritability of cancer eye has been reported to be low to moderate for young cows and moderate to high for old cows.
- Adaptability to environment
Adaptability to heat/cold, humidity, insects and disease are critical in genetic selection. For example, Bos indicus cattle inherently can withstand hot, humid climates and show resistance to insects. Animals tolerant to hot climates are less adapted to cold, however.
One trait important to many U.S. producers is the adaptability to tolerate fescue-endophyte toxicity. One method to overcome the endophyte problem is to breed cattle tolerant or resistant to the toxic endophyte. Gibb says identifying resistant cattle has been slow at best, and might be an area for the biotechnologist to identify gene markers.