How Commercial Bull Buyers Vote With Their Pocketbooks

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Relationships Between Various Performance Measures & Sale Prices of Bulls in VA BCIA Test Stations

Test and sale data from the Virginia Beef Cattle Improvement Association Central Bull Test Station program were utilized to investigate the relationship between various performance measures and the sale price of bulls. Data on Angus bulls from five test seasons (2002-03 through 2006-07), representing the tests and sales for both Senior and Junior bulls at the Culpeper and Southwest locations were evaluated. A total of 1061 bulls were included in the analysis after edits. Sale value of each individual bull was expressed as the deviation from sale average (within year, location, and test age group). Similarly, expected progeny differences (EPDs) were expressed on a percentile rank basis to account for genetic trend over time. Test performance measures (yearling weight, average daily gain) were included in the analysis as ratios to account for differences across test groups, locations, and years.

Table 1 provides correlations values between bull sale value and various performance traits. Correlation statistics provide an estimate of the relationship between two variables. Correlation values approaching 1.0 or -1.0 indicate a stronger association between the two variables of interest, whereas correlations around zero indicate a weak relationship between the variables of interest. Among the traits evaluated in this study, results suggest that higher bull sale values were associated with higher test yearling weight ratio, higher test station index (index comprised of test yearling weight and ADG), and higher test ADG ratio. Likewise, bulls with lower birth weight EPDs, and higher growth, calving ease, and ribeye EPDs also tended to have higher sale values. The variable most strongly associated with sale value was test sale index. Test sale index is comprised of a bull’s growth performance (yearling weight and ADG) as well as EPD profile.

Table 1. Simple correlations between performance traits and sale value of Angus bulls in the Virginia
BCIA test station program.

To further explain differences in sale value, equations utilizing available performance information on the bulls were developed to predict differences in sale value (Table 2). Individual test performance, consisting of test ADG and yearling weight, explained 35% of the variation in bull sale value (R² = 0.35). Growth and maternal EPDs explained 24% of the variation in bull sale value. Carcass measures alone (ultrasound IMF & REA ratios, IMF & REA EPD percentile ranks) accounted for a small proportion of the differences in bull sale value (R² = 0.11). Combining growth and maternal EPDs with carcass traits accounted for 28% of the variation in bull sale value. The best predictor of bull sale value was found when combining test performance (ADG and yearling weight) along with growth and maternal EPDs and carcass measures (R² = 0.56). Inclusion of frame score and scrotal circumference to these variables increased the R² value modestly to 0.59. In other words, utilizing all available performance data on the bulls accounted for less than two-thirds of the variability in sale value. Hence, a sizeable portion of differences in value between bulls is due to other factors. These factors may include phenotype (appearance of the bull), breeder reputation, disposition, and others not easily defined.

Table 2. Parameters to predict sale value from various performance traits for Angus bulls sold through the
Virginia BCIA test station program.

*Sale Value defined as individual bull sale price deviation from sale group average

These results suggest that buyers purchasing bulls through the Virginia BCIA Test Station program place value on a large number of traits. In general, bulls with more growth (both EPDs and individual performance) and superior calving ease tend to have more value as indicated by higher relative sale prices. Less emphasis has been placed on carcass traits relative to growth and calving ease, although carcass merit contributes to differences in sale value. A large number of variables are important in bull-buying decisions, including objective measures of performance (EPDs, ratios, etc.) as well as factors more subjective in nature.

TRAIT	Correlation with Sale Value*
BW ratio	-0.19
WW ratio	0.23
CE EPD percentile	-0.31
BW EPD percentile	-0.33
WW EPD percentile	-0.17
MM EPD percentile	-0.22
YW EPD percentile	-0.27
Test ADG ratio	0.36
Test YW ratio	0.54
Test Station Index	0.56
Test Sale Index	0.70
Frame Score	0.23
Scrotal Circumference	0.18
Ultrasound Rump Fat ratio	0.15
Ultrasound Fat Thickness ratio	0.12
Ultrasound REA ratio	0.27
Ultrasound IMF ratio	0.06
IMF EPD percentile	-0.15
REA EPD percentile	-0.20
FT EPD percentile	0.14
$B EPD percentile	-0.25
$W EPD percentile	-0.29

Prediction Variables	*Sale Value R²**
Test Performance (ADG & YW ratios)	0.35
Growth/Maternal EPDs (BW, YW, MM EPD percentile ranks)	0.24
Carcass (ultrasound IMF & REA ratios, IMF & REA EPD percentile ranks)	0.11
Station Index (2/3 YW ratio + 1/3 ADG ratio)	0.31
Sale Index (2/3 Station Index + 1/3 average BW, WW, YW, MM EPD percentile rank)	0.49
Growth/Maternal EPDs + Carcass	0.28
Test Performance + Growth/Maternal EPDs	0.54
Test Performance + Growth/Maternal EPDs + Carcass	0.56
Test Performance + Growth/Maternal EPDs + Carcass + frame score + scrotal circumference	0.59