J. Anim. Sci. 2005. 83:2926-2937
© 2005 American Society of Animal Science
Factors affecting carcass value and profitability in early-weaned Simmental steers: II. Days on feed endpoints and sorting strategies
N. A. Pyatt*,
L. L. Berger*,1,
D. B. Faulkner*,
P. M. Walker
and
S. L. Rodriguez-Zas*
* Department of Animal Sciences, University of Illinois, Urbana 61801; and
and
Department of Agriculture, Illinois State University, Normal 61790
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Abstract
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In a 4-yr study, early-weaned Simmental steers (n = 192) of known genetics were individually fed to determine EPD, performance, and carcass measurements explaining variation in carcass value and profitability across incremental days on feed (DOF) when sorted by HCW, calculated yield grade (YG), or at their highest profit endpoint (BEST). Steers were weaned at 88.0 ± 1.1 d of age, pen-fed a high-concentrate diet for 84.5 ± 0.4 d, individually fed for 249.7 ± 0.7 d, and slaughtered at 423.3 ± 1.4 d of age. Carcass weight, YG, and marbling score (MS) were predicted using real-time ultrasound throughout the finishing period to calculate carcass value and profitability at 90, 60, 30 d preslaughter and under three individual sorting strategies. Sorting strategies included marketing the 25 and 50% heaviest HCW, the highest YG at d 60 and 30, or the remaining 25% at 0-d endpoints. Independent variables were year, weaning weight EPD, yearling weight EPD, marbling EPD, DMI, ADG, HCW, YG, and MS. Profit was quadratic in response to increased DOF; the greatest economic return was noted on d 30 (pre-slaughter). Final weight, DMI, HCW, MS, and YG increased (linear; P < 0.001) with additional DOF, and ADG and G:F decreased (linear; P < 0.001). Total cost of gain was quadratic (P < 0.001), and incremental cost of gain rose at an increasing rate (quadratic; P < 0.001) with increased DOF. With increasing DOF, HCW importance decreased from 58 to 21%; MS was variable, ranging from 18 to 23%; and YG and DMI were minor contributors to profit variation. Among sorting strategies, final BW and HCW were greater for BEST, whereas other measurements were similar. Sorting individuals by HCW, YG, or at BEST increased profitability $3.70, $2.52, or $30.65 over the optimal group DOF endpoint (d 30). Retrospective analyses illustrated that sorting does not need to pinpoint each animal’s profit optimum to result in economic gains; rather, increasing HCW and decreasing weight- and YG-related penalties improved profitability. Opportunities may exist with existing and new technology to uniformly allocate cattle into feeding and marketing groups, decrease overfeeding, and increase carcass value and profitability.
Key Words: Carcass Value • Days on Feed • Feedlot Cattle • Profitability • Sorting Strategies
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Introduction
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Nutrition and management have a dramatic influence on animal performance and carcass merit. Optimum composition, weight, and economic endpoints for cattle are influenced by sex, genetics, implants, health, initial BW, diet, days on feed (DOF), performance, feed-stuff and grid prices, environment, and seasonality (Pritchard, 1999
; Mark et al., 2000). Feeder cattle are fed and marketed as heterogeneous groups, resulting in considerable variation among carcass characteristics, value, and profit. The positive and negative correlations between performance and carcass traits result in economic trade-offs that change with increased DOF. Boleman et al. (1998) indicated that 25% of audited cattle were fed too long, resulting in >1.5 cm of backfat, whereas 25% were not fed long enough, resulting in low-quality grades (QG) and lightweight carcasses. Decreased ADG and gain efficiency may occur as cattle are fed to fatter endpoints (Van Koevering et al., 1995; Mandell et al., 1997; Block et al., 2001). Fox et al. (2001) indicated that a 10% improvement in feed efficiency resulted in a 43% increase in profits. Individual cattle management increases consistency and uniformity of product, minimizes excess fat, and improves profitability by avoiding discounts. This retrospective study evaluated the interrelationships among genetic, performance, and carcass measurements, market timing, and sorting strategies on beef carcass value and profitability. The experimental objectives were 1) to determine the relative importance of EPD, performance, and carcass measurements in explaining variation in carcass value and profitability across incremental DOF; 2) to evaluate the economic benefit in value and profit of sorting cattle by HCW, calculated yield grade (YG), or at their highest profit endpoint (BEST); and 3) for an overfed subset, to evaluate the economic benefit in value and profit of sorting cattle by HCW, YG, or at their optimum profit endpoint (OPT).
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Materials and Methods
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Experimental Animals
A 4-yr study was conducted utilizing 192 early-weaned steers of known genetics (0.75 Simmental or greater breeding). Animals, diet, and management were the same as described in Pyatt et al. (2005). Animals used in this trial were managed according to the guidelines recommended in Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching(1988), and experimental protocols were submitted and approved by the Institutional Animal Care and Use Committee.
Performance Data Collection
Steer BW were taken every 28 d throughout the finishing period to evaluate feedlot performance. Weights were taken without shrink before morning feed allotments. Dry matter intake and orts were recorded daily. Individual animal ADG and G:F were calculated based on carcass-adjusted final weights. Adjusted final weight was calculated by dividing HCW by the average (annual) dressing percentage. As noted by Pyatt et al. (2005), in yr 3, one steer was removed from trial as a result of illness, and in yr 4, two steers died during the feeding period, and one steer was slaughtered early because of injury.
Collection of Ultrasound Data
Serial real-time (linear-array) ultrasound scans were used to monitor changes in subcutaneous and intramuscular fat deposition, as well as LM area (LMA) over the course of the feedlot-finishing period. Aloka 500V ultrasound equipment (Corometrics Medical Systems, Inc., Wallingford, CT) with an Aloka UST-5049-3.5-MHz transducer was used for carcass estimates. Images were interpreted using the CVI Scan Session Reporting software (Version 6.2b) in combination with Rib-O-Matic Version 3.5 software (Critical Vision, Inc., Atlanta, GA). Ultrasound measurements recorded at four times during the finishing period were used to predict changes in QG, YG, carcass value, and profitability among various endpoint scenarios. In yr 1, ultrasound measurements were recorded at d 50, 138, 198, and 246 in the feedlot, and actual carcass measurements were recorded at slaughter (249 DOF). In yr 2, ultrasound measurements were recorded at d 63, 137, 173, and 229 in the feedlot, and actual carcass measurements were recorded at slaughter (235 DOF). In yr 3, ultrasound measurements were recorded at d 63, 130, 199, and 255 in the feedlot, and actual carcass measurements were recorded at slaughter (257 DOF). In yr 4, ultrasound measurements were recorded at d 79, 148, 212, and 246 in the feedlot, and actual carcass measurements were recorded at slaughter (259 DOF).
Carcass Data Collection
Steers were slaughtered at a commercial processing facility. Animals were stunned via captive bolt and exsanguinated. Individual carcass measurements were taken for HCW, 12th rib fat thickness (BF), LMA, KPH, and marbling score (MS) as described by Pyatt et al. (2005).
Economic Analysis
Five-year price data were collected for feedstuffs, dressed beef, and grid premiums and discounts to standardize conditions across years. Ingredient prices for corn, soybean meal, alfalfa hay, molasses, and trace mineral salt were collected from annual commodity reports (1998 to 2002; NASS, 2003) as described by Pyatt et al. (2005; $108.99 and $98.93/t for diets fed during the growing and finishing periods, respectively). Average premiums and discounts (Pyatt et al., 2005) were assessed to average dressed beef price ($110.67/45.4 kg). Input costs (feed, annual cow costs, veterinary/medical and labor, feed markup, yardage, and interest) were determined as described by Pyatt et al. (2005). Annual cow costs were used to simulate a retained ownership scenario with cows of uniform size and condition. Although year-to-year variation in cow costs would be expected, conditions were standardized to the designated 5-yr time frame.
Carcass value was calculated for each animal using actual carcass weight and associated premiums and discounts for carcass merit. Predicted carcass value was calculated using predicted carcass weight and ultrasound-predicted carcass merit. Predicted carcass weight was calculated using animal weight multiplied by a dressing percent adjusted for carcass fat estimate based on previous serial slaughter data (Bruns et al., 2004). Previous research has indicated that BF and LMA (May et al., 1992; Delehant et al., 1997; Bruns and Pritchard, 2003) as well as KPH (Van Koevering et al., 1995; Bruns and Pritchard, 2003) increase linearly with time on feed. In addition, a linear increase in i.m. fat deposition has been reported with increasing DOF (Camfield et al., 1997; Delehant et al., 1997; Bruns and Pritchard, 2003). Linear assumptions were used between ultrasound scans for predicting YG and QG. Profit per steer was defined as the difference between carcass value and total input costs.
Economic simulations were conducted on animals at 30-d intervals (90, 60, and 30 d) before actual slaughter date (0 d) to pinpoint optimal DOF, carcass value, and profitability for the group. Economic implications of sorting individual cattle based on live or HCW were evaluated by conducting simulations of marketing the heaviest 25, 50, and 25% of observations (within year) on d 60, d 30 (before slaughter), and actual slaughter (d 0), respectively. Similarly, the economic implications of sorting cattle based on YG were evaluated by conducting simulations of marketing the highest 25, 50, and 25% of observations (within year) on d 60, d 30 (before slaughter), and actual slaughter (d 0), respectively. In addition, the implications of sorting cattle to their profit optimum were evaluated by simulating marketing at BEST among d 90, 60, 30, or actual slaughter (d 0). Comparisons of marketing strategies were made to illustrate the profit potential of optimizing selling endpoint. Total cost of gain (TCOG) was calculated for each animal from birth to slaughter within each marketing scenario. Incremental cost of gain (ICOG) was calculated per day and per 45.4 kg for each animal from d 90, 60, or 30 to slaughter, respectively.
Animals were purposely fed for extended DOF to monitor economic rates of change across time. Secondary analysis was evaluated on a subset of cattle fed beyond their OPT. Optimal profit endpoint was defined as the highest profit endpoint (d 90, 60, or 30) observed across the DOF. Maximum profit endpoint was calculated for individual animals by using derivatives of regression equations for profit across time. Similar economic investigation was conducted on animals within the subset, including simulations at d 90, 60, 30 (before slaughter), and actual slaughter and sorting cattle based on HCW or YG. In addition, the implications of sorting cattle to their optimum were evaluated by determining optimal DOF to achieve OPT. Similarly, subset comparisons of marketing strategies were made to illustrate the profit potential of optimizing selling endpoint.
Statistical Analyses
Data were analyzed using the MIXED procedures of SAS (SAS Inst., Inc., Cary, NC) to test differences between DOF endpoints and sorting strategies. Year, sire, DOF, or sorting strategy and the second-order interactions between year or sire and DOF or sorting strategy were analyzed as fixed effects. No interactions were significant; therefore, only the main effects of DOF and sorting strategy are reported. Linear and quadratic contrasts were evaluated across time-on-feed endpoints. Individual was used as the experimental unit for performance, carcass, and economic measurements. The stepwise option of REG (SAS Inst., Inc., Cary, NC) was used to determine regression intercept, slope, and model fit (R2) to explain variation within each marketing scenario. Separate MIXED and REG analyses were conducted among the population and subset datasets. Maximum value and profit endpoints were calculated for animals that were fed beyond their optimum using REG. Profit response was plotted across time; cattle fed beyond optimum were defined as individuals with profitability less than a previous (DOF) calculation. Time on feed was used as the sole independent variable modeled against value and profit per steer. Optimal DOF was calculated using derivatives of regression equations for steer value and profit. Independent variables used in the model included weaning weight EPD, yearling weight EPD, marbling (MARB) EPD, DMI, ADG, G:F, HCW, YG, and MS. Linear and quadratic terms were evaluated for performance and carcass measurements. Dummy variables for year effect were fixed in the model as independent variables. Dependent variables used in the model included carcass value and profit per steer.
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Results and Discussion
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Performance and Carcass Characteristics
Individual steer performance and carcass measurements were presented by Pyatt et al. (2005). Steers were finished at heavy final BW to ensure that a percentage of observations exceeded their optimum; therefore, economic calculations for optimum slaughter were simulated. Maximum profit endpoints were calculated for animals that were fed beyond their economic optimum. As a result, separate regression analyses were conducted on each individual animal exhibiting a (negative) quadratic profit response across DOF (n = 85; cattle fed beyond optimum).
Group Evaluation of Optimal Marketing Endpoint
Mean, SD, and minimum and maximum values of economic measurements for all steer observations are shown in Table 1. Extending DOF tended to increase mean carcass value and decrease observation range, primarily by improving minimum carcass value outcome. Sorting strategies tended to minimize variation, decreasing carcass value SD less than 90-, 60-, and 30-d endpoints. Profit was quadratic in response to increased DOF; the greatest economic return was noted on d 30 (preslaughter). Increased DOF resulted in a decreased profit range among the observations. Profit SD was least at actual slaughter date (0 d); however, profit potential was decreased because of an increased incidence of discounted carcasses (data not shown).
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Table 1. Mean, SD, minimum, and maximum values of economic measurements for all observations of early-weaned Simmental steers (n = 189)
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Effect of DOF on Performance, Carcass, and Economic Measures.
Performance, carcass, and economic characteristics for all cattle across DOF endpoints are summarized in Table 2. Final live weight and cumulative DMI increased (linear; P < 0.001) with additional DOF, whereas cumulative ADG and G:F decreased (linear; P < 0.001). These data agree with previous research evaluating changes in weight (Zinn et al., 1970; May et al., 1992) and performance across DOF. Hicks et al. (1990) and Van Koevering et al. (1995) reported that DMI was greater by heavier cattle, decreasing with extended time on a high-concentrate diet. Van Koevering et al. (1995) reported quadratic trends in ADG (P = 0.05) and feed efficiency (P = 0.06) with additional 14-d (feed) increments. Thonney et al. (1981) found a negative correlation between ADG and BW and a negative correlation between feed efficiency and BW. Other researchers (Barber et al., 1981; Mandell et al., 1997; Block et al., 2001) have cited poorer feed efficiency with increased DOF as cattle are fed to fatter endpoints. The efficiency of fatter cattle is adversely affected by composition of gain. Total cost of gain from birth to slaughter decreased linearly (P = 0.08) from d 90 to 30 and increased quadratically (P < 0.001) with further DOF. This finding generally disagrees with decreasing animal performance measurements; however, steers remained extremely efficient through d 30 and relatively efficient through actual slaughter date. Incremental cost of gain (per day and per 45.4 kg) rose at an increasing rate (quadratic; P < 0.001) as steers were fed for an additional 90, 60, or 30 d. Incremental cost of gain during the final 30 d approached calculated feeder-calf cost, resulting in an increased TCOG at the actual slaughter endpoint.
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Table 2. Performance, carcass, and economic characteristics for early-weaned Simmental steers (n = 189) at 90, 60, or 30 d before and at actual slaughtera
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Carcass weight, MS, and YG increased (linear; P < 0.001) with additional DOF. Zinn et al. (1970), May et al. (1992), and Van Koevering et al. (1995) reported that carcass weight increased at a decreasing rate with added DOF. The number of heavy HCW (
432 kg) discounts increased dramatically with extended DOF. At d 90 and 60, respectively, zero and one observations sustained a heavyweight discount; however, at d 30 and actual slaughter (d 0) endpoints, 18 and 51 observations had HCW >432 kg, respectively. Zinn et al. (1970) observed a stepwise increase in MS and QG across DOF. Percentage of carcasses with a MS representative of low Choice or greater increased from 60.4% at d 90 to 63.1, 65.4, and 80.4% at d 60, d 30, and actual slaughter, respectively. Rate of increase in percentage of Choice cattle was minimal from d 90 to 30 preslaughter (0.08%/ d); however, from d 30 to slaughter, rate of increase was 0.5%/d. Brethour (1997) reported each additional feeding day increased the proportion of premium Choice carcasses by 0.44% in predominantly Angus steers. Percentage of carcasses grading average Choice or greater increased from 24.6% at d 90 to 32.1, 39.4, and 38.6% at d 60, d 30, and actual slaughter, respectively. Others have reported a linear increase in MS and percentage of carcasses grading Choice or greater with additional DOF (Dolezal et al., 1982; Miller et al., 1987; May et al., 1992). Van Koevering et al. (1995) reported a linear increase in MS and percentage of Choice carcasses across slaughter date for British x Continental yearling steers, but values reached a maximum at <147 d. Percentage of carcasses with a calculated YG of 1 or 2 decreased from 82.0% at d 90 to 72.9, 61.9, and 62.6% at d 60, d 30, and actual slaughter, whereas carcasses with a calculated YG of 4 increased from 1.6 to 3.2%. Rate of decrease in percentage of carcasses grading YG 1 or 2 was 0.22 %/d, and little to no risk (0.02%/d) existed for an increased percentage of YG 4 or greater carcasses. Van Koevering et al. (1995) observed a linear increase in BF, YG, and percentage of carcasses grading YG 4 or greater with extended DOF. Brethour (1997) reported that each additional feeding day increased the proportion of YG 4 carcasses by 0.20% in predominantly Angus steers. Carcass value escalated at a decreasing rate (linear, P < 0.001; quadratic, P = 0.08) with additional DOF, whereas profit (linear and quadratic, P < 0.001) peaked at 30 d preslaughter. Nash et al. (2000) observed that profit increased at a decreasing rate for yearling heifers fed over a 120-d feeding period. Feuz (2002) evaluated the economic consequences of altering the number of DOF among pens of cattle using different types of cattle and different pricing grids. In general, increasing the number of DOF (2 wk) was profitable (premiums greater than discounts). Feuz (2002) noted an improvement in QG (average 17 to 26%); however, YG 1 and 2 premiums were decreased (–25%), and discounts associated with YG 4 (6%) and heavy carcasses (12%) were evident. When cattle were fed for 2 wk less than targeted marketing date, negative returns were observed (Feuz, 2002), and an improved percentage of YG 1 and 2 carcasses (21%) was noted, including fewer YG 4 carcasses (3%). However, cattle finished with lighter weights, and there were 13% fewer Choice carcasses. The uniformity of the pen with regard to HCW, YG, and QG also has a major effect on the success of feeding fewer or additional days. The less uniform the pen, the more likely that significant discounts will be applied to extreme cattle (Feuz, 2002).
Comparisons of regression models estimating profit with additional DOF are exhibited in Table 3. Regression models predicting profitability accounted for at least 78% of the variation among steers; however, accountability tended to decrease with additional DOF. At each endpoint, HCW and MS were the primary and secondary variables accounting for variation in profit, respectively. As carcass composition changed with additional DOF, HCW significance becomes less important relative to MS and YG. Carcass weight importance decreased from 58% at d 90 to 21% at actual slaughter (d 0), whereas MS was variable, accounting for 18 to 23% of variation. Calculated YG was a minor contributor to profit at all preslaughter endpoints but improved to explain 12% of observation variation at d 0. Cumulative DMI was a minor contributor to profit variation across DOF endpoints. To date, few studies have evaluated changes in these factors as they apply to market timing in grid-pricing structures. The current models represent the relative importance of factors affecting carcass value and profitability among early-weaned Simmental steers. We anticipate that factors would change among different biological types of cattle and under different management regimens.
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Table 3. Comparison of variation (partial R2) for models estimating profit at 90, 60, or 30 d before and at actual slaughter for all observations of early-weaned Simmental steers (n = 189)
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Effect of Sorting Strategy on Performance, Carcass, and Economic Measures.
Performance, carcass, and economic characteristics for all cattle using sorting strategies for HCW, YG, or BEST are summarized in Table 4. Final live weight was similar between strategies for sorting individuals based on HCW or YG; however, it was greater (P < 0.01) for the BEST sorting strategy. Sorting strategy did not influence cumulative ADG, DMI, G:F, or TCOG. These data agree with the results of Sainz and Oltjen (1994); however, previous research indicated that sorting fat cattle from a pen to market early improved the performance of the remaining cattle (Basarab et al., 1999; Cooper et al., 2000). Sainz and Oltjen (1994) concluded that additional DOF increased HCW, improved percentage of carcasses grading Choice, and increased overall return to the pen. Carcass weight was similar between strategies for sorting individuals based on HCW or YG, but it was greater (P < 0.001) for the BEST sorting strategy. Sorting individuals based on HCW was effective in decreasing heavyweight discounts to only one observation. In contrast, sorting steers by YG or at BEST resulted in 18 and six heavyweight observations, respectively. Sorting to each animal’s BEST resulted in the greatest mean profit, suggesting that some tolerance of heavy HCW discounts is allowable to ensure that mean HCW and carcass value are maximized. Sorting individuals to their BEST increased MS over the sorting strategies involving HCW (P < 0.05) and YG (P = 0.10). Percentage of carcasses with a MS representative of low Choice or greater was 69.4% when sorted by HCW, 71.4% when sorted by YG, or 83.8% when sorted to BEST. Percentage of carcasses grading average Choice or greater was similar among sorting by HCW, YG, or BEST, averaging 36.6, 36.8, or 38.9%, respectively. Sorting strategy did not influence YG. Percentage of carcasses with a calculated YG of 1 or 2 was similar among sorting by HCW, YG, or BEST, averaging 65.1, 64.0, or 61.8%, respectively, whereas carcasses with a calculated YG of =4 were limited to <3.2% in all cases. Both carcass value and profitability were similar between strategies for sorting individuals based on HCW or YG, but greater (P < 0.001) for the BEST sorting strategy. Sorting individuals to BEST resulted in $27.28 and $28.46 greater net returns per steer than sorting by HCW or YG. Although profit was greatest for the group marketed at the 30-d endpoint, profit potential was increased when individual sorting strategies were implemented. Sorting individuals by HCW, YG, or at BEST increased profitability $3.70, $2.52, or $30.65 over the optimal DOF endpoint (d 30) of the group.
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Table 4. Performance, carcass, and economic characteristics for early-weaned Simmental steers (n = 189) using various sorting endpointsa
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Retrospective analyses illustrate that sorting does not need to pinpoint each animal’s OPT to result in economic gains; rather, increasing HCW and decreasing heavyweight- and YG-related penalties improved profitability. Comparisons of individual sorting strategies for HCW, YG, and BEST were tested against the 30-d group endpoint (data not shown). Sorting for BEST resulted in greater (P < 0.05) final BW, HCW, MS, carcass value, and profitability compared with the 30-d endpoint. Sorting by HCW tended (P = 0.11) to improve carcass value over group optimum, whereas sorting by YG resulted in similar performance, carcass, and economic outcomes to the 30-d endpoint. Basarab et al. (1999) observed similar feed intake, efficiency, HCW, BF, LMA, MS, and lean meat yield between cattle marketed at (visual) optimal DOF of the pen or individuals sorted to a predicted DOF to maximize profit. Basarab et al. (1999) reported a 40.8% increase in cattle grading Choice in sorted cattle compared with unsorted cattle marketed as a group. Similarly, the researchers observed a 47.4% decrease in YG 3 among sorted cattle. Sorting strategies improved profitability by identifying cattle that could be fed longer to improve QG without YG 4 or overweight risks (Basarab et al., 1999), and the researchers concluded that the increased net return was primarily a result of improved ADG and more desirable distribution of carcass YG and QG. Iiams and Trenkle (1997) reported evidence that the optimal endpoint at which to sell a group of cattle or even a particular individual depends on the particular market. We recognize that grid premiums and discounts would significantly alter target composition and market date; however, based on historical (5-yr average) pricing and our breed and management specifics, present data may be used as a benchmark for future research.
Cattle feeders recognize acceptable DOF ranges for marketing different classes of cattle. Current technology does not exist to realize profit potential exhibited by the BEST strategy. Previous research has not compared optimal DOF to maximize profitability for a group vs. individuals; however, various sorting strategies conducted 3 to 6 mo before slaughter have shown potential for improving carcass uniformity and profit of finished cattle. Sorting increased carcass weight (30 kg) and consistency of the group (Koontz et al., 2000). The SD of sorted cattle was smaller for carcass weight (13%) and BF (35%) than unsorted pens (Koontz et al., 2000). Sainz and Oltjen (1994) used a computer model of growth to integrate initial animal weight, frame size, BF, and initial feeding information to sort feeder cattle into uniform groups 4 to 6 mo before slaughter, and they concluded that variability in carcass BF of sorted cattle was decreased by 22.6% compared with unsorted cattle. Boleman et al. (1998) estimated that 23.5% of (unselected) audited cattle were considered outliers, whereas individual management systems have decreased these numbers to approximately 4%. Basarab et al. (1999), Koontz et al. (2000), and Trenkle (2000) proved that discounts often affect profitability more than premiums. Trenkle (2000) indicated that removing the bottom 10% of the carcasses with the least value improves the economic value of the remaining carcasses by $17.50 to $21.09. Net returns of sorting range from $11 to $33 per animal (Basarab et al., 1999; Koontz et al., 2000; Lusk et al., 2003), but net returns may depend on the number of pens to which cattle can be sorted. Schroeder and Graft (2000) reported average revenues were improved $15.14 to $34.74 per animal if producers knew the QG and YG of their cattle before slaughter and optimally marketed each animal, as opposed to simply marketing all cattle on a live-weight, dressed-weight, or grid basis. Trenkle (2001) sorted incoming cattle by frame size and initial BF measurement and concluded that sorting based on initial BF was more profitable than sorting by frame score. In the current study, sorting cattle by either HCW or YG was comparable in profitability. Trenkle and Iiams (1997) indicated that ultrasound scanning feeder cattle to measure both LMA and BF was most effective in sorting cattle into groups with more potential to have high-yielding carcasses.
Comparisons of regression models estimating profit for all cattle using sorting strategies for HCW, YG, or BEST endpoint are summarized in Table 5. Regression models predicting profitability accounted for at least 80% of the variation among steers. Sorting by HCW improved accountability of profit variation compared with sorting by YG or BEST. Among sorting strategies, HCW and/or MS were the primary or secondary variables accounting for variation in profit. Carcass weight was the most important variable when sorting by HCW or BEST, whereas MS was most important in accounting for profit variation when sorting by YG. Marbling score was the second most important variable when sorting by HCW or BEST, whereas HCW was second most important in accounting for profit variation when sorting by YG. Trenkle (2000) reported that HCW, MS, and YG contributed to net carcass value, but that HCW was the most significant factor. In our analysis, cumulative ADG, YG, DMI, and MARB EPD accounted for minor additional variation in profit differences among cattle sorted by HCW. These data agree with those of Trenkle (2000), who reported that ADG accounted for only a small portion of the overall variation in carcass value among young cattle. Likewise, Trenkle (2000) noted that initial gain (first 3 to 5 wk) identified only 16% of carcass observations with the least net value in a value-based grid. Feed efficiency accounted for an additional 6% of variation in net returns for cattle sorted by YG or BEST. By selling fat cattle early and feeding lean cattle longer, sorting by YG effectively eliminated variation in profit because of the criterion variable. Trenkle (2000) reported greater net returns when sorting cattle based on initial BF among small-framed steers compared with large-framed animals. Likewise, YG did not influence profit outcome for animals marketed at BEST. In general, performance and carcass measurements agree with previous sorting strategies; however, models represent the relative importance of factors affecting carcass value and profitability among early-weaned Simmental steers. As with DOF results, we would anticipate that factors would change among different biological types of cattle and under different management regimens.
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Table 5. Comparison of variation (partial R2) for models estimating profit using various sorting endpoints for all observations of early-weaned Simmental steers (n = 189)
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Postslaughter Evaluation of Optimal Marketing Endpoint Among Overfed Cattle
Economic outcome of probable marketing endpoints for steers fed beyond their economic optimum is summarized in Table 6. Extending DOF affected mean carcass value quadratically; the 30-d endpoint generated the greatest revenue. Data range and SD tended to be smaller for the subset compared with the entire population, primarily because of greater minimum carcass value observations. Sorting strategies, particularly by HCW or OPT, minimized variation, decreasing carcass value SD less than all group DOF endpoints. Profit was quadratic in response to increased DOF; the greatest economic return was noted for d 30. Similar to carcass value, profit data range and SD were smaller for the subset observations when compared with the entire population. At all DOF endpoints and among each sorting strategy, minimum profit was greater among the subset observations than the entire population. These data suggest that steers with the least profit margin among the entire population would likely benefit from greater time on feed to optimize weight and grade outcome. Uniformity of the subset is evident with improved range and SD.
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Table 6. Mean, SD, minimum, and maximum values of economic measurements for early-weaned Simmental steers fed beyond optimum (n = 85)
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Effect of DOF on Performance, Carcass, and Economic Measures.
Performance, carcass, and economic characteristics across DOF endpoints for steers fed beyond optimum are summarized in Table 7. Final live weight and cumulative DMI increased (linear, P < 0.001) with additional DOF, whereas cumulative ADG and G:F decreased (linear, P < 0.001). These data agree with trends of the entire population and previous research (Zinn et al., 1970; May et al., 1992; Hicks et al., 1990). Final live weight and ADG tended (P 
0.14) to decrease at an increasing rate, suggesting that cattle were approaching a point of greater diminishing returns. However, DMI and G:F did not exhibit similar trends. Total cost of gain from birth to slaughter was quadratic (P < 0.001) with increased DOF. Again, this finding generally disagrees with decreasing animal performance measurements; however, even overfed steers remained relatively efficient through d 30. Daily ICOG rose at an increasing rate (linear and quadratic, P < 0.001) as steers were fed for an additional 90, 60, or 30 d. Similarly, ICOG (per 45.4 kg) increased linearly (P < 0.001) and tended (P = 0.12) to be quadratic as steers were fed for additional days.
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Table 7. Performance, carcass, and economic characteristics for early-weaned Simmental steers fed beyond optimum at 90, 60, or 30 d before and at actual slaughter (n = 85)a
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Carcass weight increased (linear, P < 0.001) at a decreasing rate (quadratic, P = 0.07) with additional DOF. The number of heavy HCW (432 kg) discounts increased dramatically with extended DOF. At d 90 and 60, zero and one observations sustained a heavyweight discount; however, at d 30 and actual slaughter endpoints (d 0), 17 and 42 observations had HCW >432 kg, respectively. Marbling score was quadratic (P < 0.05) with additional DOF, increasing from d 90 to 30, but decreasing by d 0. A decrease in MS at d 0 was unexpected and not biologically probable, although Van Koevering et al. (1995) reported a quadratic response in MS, where values reached a plateau with added DOF. Percentage of carcasses with a MS representative of low Choice or greater increased from 77.7% at d 90 to 83.5, 88.2, and 77.7% at d 60, d 30, and actual slaughter, respectively. Rate of increase in percentage of Choice cattle was 1.75%/d from d 90 to 30 preslaughter; however, it is unclear why QG would decrease the final 30 d on feed. Percentage of carcasses grading average Choice or greater increased from 34.1% at d 90 to 44.7, 54.1, and 43.5% at d 60, d 30, and actual slaughter, respectively. Calculated YG increased (linear, P < 0.001) but at a decreasing rate (quadratic, P = 0.07) with additional DOF. Again, a decrease in YG at d 0 was unexpected, but differences between means are small and not biologically important. This result differs from traditional thought regarding growth curve analysis, from which one would expect YG to increase at an increasing rate with extended DOF. Percentage of carcasses with a calculated YG of 1 or 2 decreased from 65.9% at d 90 to 52.9, 44.7, and 45.9% at d 60, d 30, and actual slaughter, whereas carcasses with a calculated YG of 4 increased from 3.5% to 7.1%. The rate of decrease in percentage of carcasses grading YG 1 or 2 was 0.22%/d, whereas the percentage of YG 4 carcasses increased 0.4%/d. Carcass value escalated at a decreasing rate (linear and quadratic, P < 0.001) across DOF, peaking at 30 d preslaughter. Profit responded similarly, increasing through d 30, then decreasing sharply with additional DOF (linear, P < 0.05; quadratic, P < 0.001).
Comparisons of regression models estimating profit with additional DOF for steers fed beyond their economic optimum are shown in Table 8. Regression models predicting profitability accounted for at least 74% of the variation among steers; however, accountability tended to decrease with additional DOF. At each pre-slaughter endpoint, HCW and MS were the primary and secondary variables accounting for variation in profit, respectively. At actual slaughter, HCW remained the primary variable of importance, but YG was secondary in accounting for profit variation. With additional DOF, HCW decreased in relative importance for determining profitability, ranging from 63% at d 90 to 22% at actual slaughter (d 0). Importance of MS was variable with extended DOF, ranging from 10% at d 60 to 16% at d 30. Similarly, importance of YG was variable, ranging from 6% at d 90 to 17% at d 0. Cumulative DMI, ADG, G:F, MARB EPD, and weaning weight EPD were minor contributors to profit variation across pre-slaughter endpoints, yet they did not explain additional variation at the d-0 endpoint. As before, these models represent the relative importance of factors affecting carcass value and profitability among early-weaned Simmental steers, and they might change among different biological types of cattle and under different management regimens.
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Table 8. Comparison of variation (partial R2) for models estimating profit at 90, 60, or 30 d before and at actual slaughter for early-weaned Simmental steers fed beyond optimum (n = 85)
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Effect of Sorting Strategy Performance, Carcass, and Economic Measures.
Performance, carcass, and economic characteristics for steers fed beyond optimum using sorting strategies for HCW, YG, or OPT are summarized in Table 9. Final live weight, ADG, DMI, G:F, and TCOG were similar between individual sorting strategies. Final live weights tended (P = 0.10) to differ between YG and OPT sorting strategies. Carcass weight was greater (P < 0.05) when sorted by YG compared with OPT and tended (P = 0.13) to be greater than weight-sorted carcasses. Trends in HCW did not translate to economic differences because of an increased incidence of heavyweight discounts among YG-sorted cattle. Sorting individuals based on HCW or OPT was effective in decreasing heavy HCW discounts to only one observation for each tactic, but sorting steers by YG resulted in 13 heavyweight observations. Sorting approach did not alter final MS or calculated YG outcome. Percentage of carcasses with a MS representative of low Choice or greater was 84.5% when sorted by HCW, 85.6% when sorted by YG, and 85.9% when sorted to OPT. Percentage of carcasses grading average Choice or greater was similar among sorting by HCW, YG, or OPT, averaging 52.4, 55.9, or 50.6%, respectively. Percentage of carcasses with a calculated YG of 1 or 2 was similar among sorting by HCW, YG, or OPT, averaging 49.4, 47.1, or 52.9%, respectively, whereas carcasses with a calculated YG of 4 seemed greater for cattle sorted by HCW (7.1%), intermediate when sorted by YG (4.7%), and least when sorted to OPT (3.5%). Both carcass value and profitability were similar among sorting comparisons. Numeric differences were observed among approaches; the OPT sorting strategy resulted in greater returns ($6.20 and $13.89 per animal, respectively) than sorting by HCW or YG. In addition, sorting by HCW exhibited a $7.69 per animal advantage over sorting by YG. Sorting by YG resulted in lower profitability relative to other schemes, primarily because of a greater incidence of heavy HCW discounts. As observed among the entire population of observations, profit was greatest for the group when marketed at the 30-d endpoint. Nonetheless, profit potential was increased when individual sorting strategies were implemented. Among the more uniform subset observations, sorting individuals by HCW was similar in net returns to the optimal DOF endpoint, whereas OPT increased profitability $1.84 over d-30 profitability. Final weight and HCW were greater for 30-d endpoint compared with all sorting strategies. Sorting by HCW or OPT maintained or improved profitability relative to 30-d endpoint by avoiding heavy HCW discounts.
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Table 9. Performance, carcass, and economic characteristics of early-weaned Simmental steers fed beyond optimum using various sorting endpoints (n = 85)a
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Comparisons of regression models estimating profit for cattle fed beyond their optimum using sorting strategies for HCW, YG, or OPT are summarized in Table 10. Regression models predicting profitability accounted for at least 77% of the variation among steers. Sorting by HCW or OPT improved accountability of profit variation compared with sorting by YG. Among sorting strategies, HCW and MS were the primary and secondary variables accounting for variation in profit. Carcass weight accounted for greater variation in profitability when sorting by HCW or YG, but less when sorted to OPT. Conversely, MS accounted for greater variation in profitability when sorting at OPT but less when sorted by HCW or YG. These data suggest that saleable weight is important regardless of marketing strategy, but the composition of that weight is more important when animals are sorted to OPT. This result agrees with previous research by Trenkle (2000), who found that not only HCW, but also the composition of that weight (MS and YG), were important factors in determining net carcass value. Furthermore, YG accounted for 10.7 and 7.3% additional variation when sorted by HCW or OPT, respectively, but YG was not a source of profit variation when used as a sorting criteria. Cumulative G:F accounted for 3 to 7% of additional variation across all sorting scenarios. Similarly, MARB EPD was retained in each stepwise model across sorting strategy, but it accounted for only minor additional variation in profit differences among the subset observations. As before, these models apply specifically to early-weaned Simmental steers, and results might change with other types of cattle and management schemes.
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Table 10. Comparison of variation (partial R2) for models estimating profit using various sorting endpoints for early-weaned Simmental steers fed beyond optimum (n = 85)
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Costs of Sorting
Feedlot managers are concerned about lost yardage revenue as a result of removing cattle from a pen early. In the current experiment, only 25% of cattle were removed before the optimum DOF of the pen would have occurred (30 d). However, profit calculations in these examples used prorated yardage for cattle marketed at 30- and 0-d endpoints, holding yardage revenue constant for the pen. Previous research has observed that pen utilization was not greatly affected by sorting and that 14% of the cattle were taken out of the pen early in simulations removing HCW outliers (P. T. Anderson, VetLife, Inc., Overland Park, KS, personal communication, 2004). In the current experiment, profit calculations above did not account for equipment, labor, and processing costs. Lusk et al. (2003) reported a cost estimate for ultrasound technician charges ranging from $3 to $17 per animal but noted that some cost could be mitigated by economies of size in large feedlots. Koontz et al. (2000) estimated the cost of sorting at approximately $4 to $5 per animal. Cost estimates are comparable with returns of sorting by HCW or YG, but less cost prohibitive using BEST. We recognize that steers in this trial were relatively uniform, originating from the same herd, and we anticipate that greater economic benefits may be observed among less uniform populations. Additionally, profit improvements attributable to sorting are compared with the market optimum of the group (30 d) and may be larger in a commercial setting. Producers are not guaranteed (or likely) to pinpoint the optimum of the group via visual appraisal alone. Lusk et al. (2003) argued that any benefit added by predictive power and strategically timing cattle to market would be in addition to profit estimates, which offsets technology costs and results in a direct return for the producer. Stanton (1997) reported that reworking and commingling cattle could have a negative effect on ADG (–5.6%) and feed efficiency (–6.9%). Conversely, Houghton and Turlington (1992) reported no significant differences in ADG of cattle sorted 7 to 10 d before slaughter. Severity of possible decreases in performance can likely be directly related to distance traveled, pen size, commingling, recovery time, facilities, and environmental conditions. Changes in feeding and social environment may lead to altered composition of gain before market. Thus, costs associated with such strategic management should be considered in calculations for carcass value and profitability.
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Implications
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Models accounted for a majority of the value and profit variation of early-weaned Simmental steers across days and sorting strategies. With increasing days on feed, importance of hot carcass weight decreased, marbling score was variable, and yield grade and dry matter intake were minor contributors to profit variation. Factors would be expected to change with different cattle types and management strategies. Sorting individuals by body weight, yield grade, or at highest profit endpoint increased profitability over the optimal days on feed endpoint (d 30) of the group. Retrospective analyses illustrated that sorting need not pinpoint each animal’s profit optimum to result in economic gain, but that increasing hot carcass weight and decreasing penalties improved profitability. Current results are based on 5-yr average prices and may serve as a discrete benchmark. Opportunities exist to use existing and new technology to allocate cattle into feeding and marketing groups that will decrease overfeeding and increase carcass value and profitability.
1 Correspondence: 164 Animal Sciences Laboratory, 1207 W. Gregory Dr. (phone: 217-333-2006; fax: 217-244-7861; e-mail: llberger{at}uiuc.edu).
Received for publication December 10, 2004.
Accepted for publication August 15, 2005.
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Abstract
Introduction
