Date of Award
Master of Science
John C. Waller
E.R. Lidvall, F. David Kirkpatrick
The objective of this study was to partition the total variability of price received for performance tested bulls into that which is attributed to various selected criteria. The records of twelve Tennessee performance tested bull sales (six junior and six senior) were compiled. These records, collected by the University of Tennessee Extension Service from 1982 through 1987, consisted of 343 junior bulls and 250 senior bulls. An adjusted sale price was calculated using an index which consisted of standardizing feeder cattle prices, slaughter bull prices and an agricultural consumer price index to a 1987-year dollar equivalent, for both data sets. A first analysis was conducted to partition out the effects of the following four discrete variables: (1) year; (2) breed; (3) sire; and (4) preweaning management. By using the beta value estimates of these factors to adjust the data, all records were equalized to a 1987 year, British breed, artificial sire, no-creep feed management system.
In the second analysis, adjusted sale price was set to equal nine commonly available performance variables. A stepwise regression resulted in 34.06 and 50.69 percent of the total variability in the sale price explained by the performance variables in the junior and senior tests, respectively. For the junior test, adjusted 365-day weight and frame score explained 32.19 percent of the variation and were highly significant (P < .001). Average daily gain on-test, off-test age, and off-test weight added a combined 1.87 percent to the explained portion of variation. In the senior test however, average daily gain on-test and frame core explained 36.60 and 11.28 percent of the variation, respectively. The effects of these two variables were also highly significant (P < .001). Adjusted 205-day weight, age off-test, and weight off-test added 2.81 percent to the explained portion in sale price.
The variables age of dam, adjusted 365-day weight, weight per day of age and adjusted 365-day height in the senior test and age of dam, adjusted 205-day weight, weight per day of age and adjusted 365-day height in the junior test were not used in the forward selection procedure of the stepwise regression because they did not meet the preselected level of significance (P < .10).
Conclusions may be drawn that frame score and some level of gaining performance for a specified age were important traits when considering prospective herd sires. Also, age of dam had very little effect on the choice of herd sire and, weight per day of age and adjusted 365 day height were not considered when frame score and average daily gain on-test are available to the bull buyers. However, it is important to understand that bull buyers did utilize the performance data available to them when selecting prospective herd sires from test stations.
Hayden, Ronald G., "Evaluation of factors affecting sale price of performance tested bulls. " Master's Thesis, University of Tennessee, 1989.