Advancements in Producer Applications
Performance Data Collection Comparisons
Accuracy of measurement methods of performance data compared.
by Kasey Miller for Angus Productions Inc.
HOUSTON, Texas (April 20, 2012) — Reporting accurate measurements is required for selection and culling decisions, Trent Smith, Mississippi State University (MSU), told participants at the Beef Improvement Federation (BIF) Research Symposium and Annual meeting in Houston April 18-21.
Performance data is integral to production, but measurement systems vary in terms of cost, convenience and the producer’s ability, including labor and facilities. Birth weight and hip height (to determine frame score) are often used for selection and culling decisions. Incorrectly reported information can severely affect expected progeny differences (EPDs) and decisions based on those genetic predictors.
For birth weight measurements, Smith compared collection methods of visual appraisal, hoof circumferance with a hoof tape, handheld scales and digital scales, which were used as the standard. Of the three methods (as digital was used as the standard), all were positively correlated, but the hoof tape was the most variable. Smith said that hoof tape and visual estimates underestimated high birth weights, but visual was actually pretty accurate and increased accuracy later in the season. Granted, visual appraisal is dependent upon each cowboy.
For hip height, the BIF Guidelines recommend measuring directly over the hooks. Researchers compared using a visual appraisal with a pre-measured board on the opposite side of the chute; using a measuring tape from the top of the chute to the hooks, then subtracting that from the total height from the top of the chute to the floor; and an altitude stick (the standard). Measurements were also taken when the head was restrained to see if that made a difference in accuracy.
Cows and calves were observed and were also assigned a chute score from 1 (docile) to 5 (aggressive). Smith reported that correlations were high, but that the tape was the most variable. Unrestrained cows showed more variations, because sometimes the cows were too long for the chute.
When calf chute score was higher, the hip height measurement was lower, especially when the animal was restrained. Smith explained that when restrained, calves would often pull back, which would affect measurement. Cows showed no difference with head restraint, but it did affect calves.
The measuring tape tended to overestimate height, and visual appraisal underestimated height, Smith reported. Operator error also affected measurement.
Smith recommended confining cattle, but with no head restraint, for more accurate data. Level floors and chutes must be used to get accurate measurements with the altitude stick. Make sure there are no obstructions to the visual measuring board and that it is clearly marked. The position of the tape is also important. As length of the animal changes, the angle of the tape to meet the animal also changes and affects the reading. Finally, he said, be patient and take the time to collect accurate data, as that will affect EPD readings and management decisions.
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