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From the 1999 Nebraska Beef Report A major concern for cattle producers is carcass discounts due to overweight and over fat cattle. A research project conducted by the University of Nebraska Cooperative Extension Service, involving over 4,000 head of cattle and five commercial feedlots, was conducted to evaluate marketing and sorting systems to reduce discounts on overweight and over fat cattle. Rib palpation (low-tech) and ultrasound (high-tech) procedures were used to estimate fat depth at re-implant time to try and identify discounts. At the beginning of the study, cattle were split into three groups consisting of the control group, the low-tech group and the high tech group. Each group was then processed with the feedlots' normal procedures. At re-implant time, all three pens were sorted according to weight. The control pen was used as the benchmark and the low- and high-tech pens were sorted into overweight cattle, normal cattle and underweight cattle. The cattle in the low-tech pens were individually weighed, rib palpated and visually inspected to estimate fat depth. The cattle in the high-tech pens were also individually weighed, and ultrasound was used to determine fat depth. Overweight cattle were tagged with a purple ear tag, normal cattle were not tagged and underweight cattle were tagged with an orange ear tag. At marketing time the control group was sold as an entire pen. Overweight cattle earmarked for early sale were marketed seven to 14 days before the control pens. Cattle identified as normal weight cattle were marketed seven to 14 days after the control pen. Underweight cattle were marketed from seven to 14 days after the normal weight cattle. Researchers found a correlation between re-implant weight and carcass weight which suggests cattle that are heavier at re-implanting have the potential to have heavier carcasses at slaughter. The researchers felt this was a good way to identify overweight cattle. The sorting systems were not, however, able to consistently identify and reduce the number of discounts for over fat carcasses. Most of the carcasses with Yield Grades of 4 or greater were not in the early sale groups. This indicates over fat cattle could not be identified at re-implant time. This holds true for both the low- and high-tech methods, however, more occurred in the low-tech method. Researchers found that neither rib palpation nor ultrasound predicted carcass fat depth satisfactorally at re-implant time. Two plausible explanations for the inability of the system to reduce Yield Grade 4 carcasses are 1) fat depth determinations at re-implant time were inaccurate, or 2) cattle deposited fat at different rates between re-implant time and slaughter, according to research. Since ultrasound has, in the past, been determined to be reasonably accurate for measuring fat depth, the researchers feel the greater source for error comes from the rate of fattening. Economics also played a role in this research project. One test group was sold due to a high market bid and the owner's decision to sell. |
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