I am often asked “At what weight should my steer be sent to harvest?” The typical extension answer is, “It depends.” Unlike chickens and hogs that have been selected to be very uniform in weight at harvest, there is a lot of variation in cattle type.
The best way to explain this variability is to think about the difference in the weight of humans. While there is some debate as to which formula most accurately describes the ideal weight, my predicted ideal weight should be 158 – 171 pounds at my height of 5 feet, 11 inches. A male that is 5 feet, 8 inches tall should weigh 148 – 153 pounds. Ideal weight not only depends on height, but also gender. Women at 5 feet, 11 inches tall have an ideal weight of 149 – 156 pounds and at 5 feet, 8 inches their ideal weight is 139 – 141 pounds.
Frame score and projected harvest weight
Cattle are no different; height and gender matter. Most producers are familiar with the term, frame score. Frame score is a convenient way of describing the skeletal size of cattle. Most animals should maintain the same frame score throughout their life, regardless of when they are measured. No one frame size will be best for all feed resources, breeding systems and markets. Large-framed animals tend to be later maturing while small framed animals tend to be earlier maturing. The earlier maturation rate of small frame cattle generally make them preferred for grass finishing as they reach market sooner without requiring a second winter of feeding.
Hip height should be measured directly over the hook bones (Figure 1).
This measurement is then adjusted for age and gender. The measured hip height is converted to a frame score using an equation or a table. (See Chart 1. The complete table can be found under “Software/Reports” at http://beefcattle.ansci.cornell.edu/.)
As an example, the hip height of your 8-month-old steer is 43 inches. This equates to a frame score of 4. At the bottom of this column is the projected finish weight: 1,102 pounds. Likewise your 7-month-old heifer measures 41 inches with a predicted finish weight of 882 pounds.
This table assumes that the cattle will be harvested at 0.5 inch backfat, which is the most likely degree of fatness for them to grade low Choice. If you harvest at lower levels of backfat, then the harvest weight will be lighter than predicted in the table.
Body condition score and market readiness
While frame score provides a general idea about what weight to harvest, the degree of fatness is the final determinant. Acquiring the skill in seeing fat is not difficult. For many beef producers, body condition score (BCS) is a familiar tool used in determining the proper condition of their cows at key points during the production year. Fortunately, this same tool can be used to determine when the animal is ready for harvest. (See Chart 2.)
For most markets, cattle should have at least 0.20 inches of back fat to produce an acceptable carcass. Fat is an insulator and limits a process known as “cold-shortening of the muscle fibers.” This can occur when the carcass cools too quickly following harvest, creating tough beef. Back fat is also associated with marbling and generally increases flavor, tenderness and juiciness. Therefore most cattle should be harvested at a BCS at 5 or greater.
For many grass-finished cattle, they will be harvested at BCS 5-6. If the pasture is managed well and if there are appropriate genetics (primarily frame score), then this will allow cattle to be finished on grass at a young age and before their second winter. Finishing cattle on stored forage increases the cost of production and reduces enterprise profitability. It may also result in older cattle, which can reduce eating quality, especially tenderness.
For grain-finished cattle, the BCS would approach 7-8 due to more energy in the diet. In general, this market demands beef with a higher degree of finish.
Regardless of the production system, the degree of carcass fatness should fit the demand of your customers.
So, when is your animal ready for harvest? “It depends” on height frame score), gender and degree of fatness (body condition score). The standard Extension answer, this time, is not avoiding your question!
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