One hundred seventy-four mixed crossbred yearling steers (789 Ib) were used to determine if ultrasound technology could be used to predict eventual marbling score in incoming feedlot cattle. Implants were also administered to study the effects of anabolic agents on marbling. Steers were fed in a single pen at a commercial feedlot for an average of 127 days, slaughtered, and carcass data were collected. Implanted cattle gained significantly more weight (P \u3c .05) than nonimplanted cattle. Steers implanted with Revalor gained weight more rapidly than Synovex implanted cattle. Steers that were implanted with Revalor showed a significant decrease in marbling score when compared to no implant and Synovex groups. The percentage of choice carcasses for no implant, Revalor, and Synovex were 65.5, 47.4, and 68.4. The correlation between initial ether extract, as estimated by ultrasound, and marbling score was .45 and a prediction equation including coat color, initial ether extract, and Revalor implant accounted for 26.59% of the variability in the final marbling score

Senn, L. A.

Wagner, J. J.

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South Dakota State UniversityOpen PRAIRIE: Open Public Research Access InstitutionalRepository and Information ExchangeSouth Dakota Beef Report, 1994 Animal Science Reports1994Using Ultrasound Techonology in IncomingFeedlot Steers to Predict Marbling and the Effect ofAnabolic Agents on MarblingL. A. SennSouth Dakota State UniversityJ. J. WagnerSouth Dakota State UniversityFollow this and additional works at: http://openprairie.sdstate.edu/sd_beefreport_1994Part of the Animal Sciences CommonsThis Report is brought to you for free and open access by the Animal Science Reports at Open PRAIRIE: Open Public Research Access InstitutionalRepository and Information Exchange. It has been accepted for inclusion in South Dakota Beef Report, 1994 by an authorized administrator of OpenPRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. For more information, please contactmichael.biondo@sdstate.edu.Recommended CitationSenn, L. A. and Wagner, J. J., "Using Ultrasound Techonology in Incoming Feedlot Steers to Predict Marbling and the Effect ofAnabolic Agents on Marbling" (1994). South Dakota Beef Report, 1994. Paper 18.http://openprairie.sdstate.edu/sd_beefreport_1994/18dm Using Ultrasound Technology in Incoming Feedlot Steers to Predict Marbling and the Effect of Anabolic Agents on Marbling L.A. Sennl and J.J. Wagnef Department of Animal and Range Sciences One hundred seventy-four mixed crossbred yearling steers (789 Ib) were used to determine if ultrasound technology could be used to predict eventual marbling score in incoming feedlot cattle. Implants were also administered to study the effects of anabolic agents on marbling. Steers were fed in a single pen at a commercial feedlot for an average of 127 days, slaughtered, and carcass data were collected. Implanted cattle gained significantly more weight (P < .05) than nonimplanted cattle. Steers implanted with Revalor gained weight more rapidly than Synovex implanted cattle. Steers that were implanted with Revalor showed a significant decrease in marbling score when compared to no implant and Synovex groups. The percentage of choice carcasses for no implant, Revalor, and Synovex were 65.5, 47.4, and 68.4. The correlation between initial ether extract, as estimated by ultrasound, and marbling score was .45 and a prediction equation including coat color, initial ether extract, and Revalor implant accounted for 26.59% of the variability in the final marbling score. Key Words: Implants, Ultrasound, Marbling USDA quality grades. According to  the 1991 National Beef Quality Audit, $21.68/carcass was lost due to insufficient amounts of marbling and another $219.25 from excess fat. These nonconformities are pushing the beef industry toward a value based marketing system in order to more adequately meet consumer demand for quality and lean. With value based marketing, risk will be transferred from buyer to  seller. Management and marketing tools will be needed to minimize this risk. Ultrasound technology could provide a means to make decisions such as implant or marketing strategy at feedlot arrival. The objectives of this study were to evaluate the use of ultrasound technology to  sort incoming feedlot cattle by marbling potential and to  study how implants affect marbling. Materials and Methods One hundred seventy-four crossbred yearling steers (789 1b) were delivered to  a commercial feedlot3 in central South Dakota. Steers had been on pasture in western South Dakota and had not been implanted during the grazing season. Introduction At  processing, cattle were weighed, vaccinated, treated for parasites with Ivomec4 Implants have been used in the beef and implanted. Hip height was measured and industry to  improve growth rates, feed coat color was recorded as red, black, or other. conversion, and cutability. However, some Llltrasound scans for initial rib eye area, 12th rib studies have shown that implants may reduce fat, and percentage of intramuscular fat were marbling score and, therefore, reduce collected by Middle America Network of Mapleton, lowa, and evaluated by lowa State 'Graduate Assistant. 'Associate Professor. 3R and L Feedyard, Kimball, SD. 4Product of MSD AGVET, Rahway, NJ. University, Ames, Iowa. Implants (Revalor5, Synovex6, or no implant) were administered in a completely random design. Steers were then fed in one pen for an average of 127 days, slaughtered, and carcass data collected after a 24-hour chill. Final weight was determined by dividing hot carcass weight by average dressing percentage at each slaughter date. Average daily gain and carcass traits were evaluated using GLM procedures of SAS. Class variables included in the model were color and treatment. Treatment means were separated using orthogonal contrasts. The model to predict marbling score was developed using forward selection regression techniques. The full model evaluated was marbling score = a + b (blk) + c (red) + d (Rev) + e (Syn) + f (hpht) + g (in fat) + h (in REA) + i (in EE) + j (in wt)  + error, where blk = black steers, red = red steer, Rev = Revalor, Syn = Synovex, hpht = hip height, in fat = initial fat, in REA = initial rib eye area, in EE = initial ether extract, and in w t  = initial weight. Two-way interactions were also examined in the analysis. Only variables that were significant (P<.10) were left in the reduced model. Percentage choice data were tested using Chi square analyses. Results and Discussion --Table 1 shows the effect of implant on weight and average daily gain. Implants had a significant effect (P< .05) on average daily gain as compared to controls. Steers implanted with Revalor had greater (P< .05) average daily gains when compared to Synovex implanted steers. Table 1. Weight and average daily gain (Ib)a Item Control Revalor Synovex Initial weight, Ib 787 8.97 783 * 8.40 79 1 * 8.50 Final weight, Ib 1142 * 14.20 1228 * 12.02 1186 k 11.75 Average daily gain, lbbC 2.78 k .07 3.51 .09 3.17 f .09 'Means 2 standard error. blmplant vs control (P < .05). 'Revalor vs Synovex (P< .05). Table 2 displays carcass data for the steers. Implants did not affect hot carcass weight, 12th rib fat, rib eye area, or yield grade. Revalor significantly reduced (P < .05) marbling score. Percentage of choice carcasses for control, Revalor, and Synovex were 65.5, 47.4, and 68.4, respectively. These differences were statistically significant as determined by Chi square (P<.10). Table 3 shows initial fat, initial rib eye area, and initial ether extract as determined by ultrasound. lnitial fat thickness averaged .13 inch and ranged from .06 to .25 in. Initial ether extract as predicted by ultrasound averaged 1.74% and ranged from .957 to  2.85%. The correlation between initial ether extract and marbling score was .45. Table 4 shows the reduced model predicting marbling score. Initial ether extract entered the model first and accounted for 19.86% of the variability. For each additional percent unit of ether extract, marbling score increased .56 units. The second variable to enter the model was Revalor which accounted for an additional 3.84% of the variation in marbling score. If Revalor was used as the implant, marbling score appears to have been reduced as compared to the nonimplanted control steers. However, the effect of Revalor on marbling appeared to depend on the initial ether extract content as the interaction between Revalor and ether extract 6Hoescht-Roussel, Somerville, NJ. %yntex Animal Health, Des Moines, IA. Table 2. Implant effect on carcass traitsa Control Revalor Synovex Hot carcass wt, Ib 694 i 8.69 747 + 3.33 722 + 7.17 Fat thickness, in. .35 + .02 .43 * .I41 .39 ~t .02 Rib eye area, in.' 12.39 * .15 12.99 * .18 12.33 * .97 Yield grade, units 2.54 * .08 2.53 + .08 2.75 + .10 Marbling score unitsbCd 5.01 * .08 4.76 * .08 5.01 * .08 Percentage choicee 65.5 47.4 68.4 "Means * standard error. 4.00 = slighto, 5.00 = smallo. 7mplant vs no implant (P < .05). dRevalor vs Synovex (P < .05). eChi square analysis (P < .lo). Table 3. Initial values determined by ultrasound Variable Minimum Maximum Average Std Dev Initial fat, in. .06 .25 .13 .03 initial rib eye area, in.2 6.35 11.69 8.88 1.04 Initial ether extract, % .96 2.85 1.74 .38 Table 4. Regression statistics for the equation predicting marbling score Regression Standard Partial coefficienta errora R2 P Intercept 3.98 .23 .OOO 1 Ether extract .56 .13 1986 .0001 Revalor -1.02 .46 .0384 .0280 Black .19 .10 .O 148 .0570 Revalor x ether extract .45 .26 .0141 .0838 "Marbling score units (4.00 = slight0, 5.00 = small0. bProbability that the regression coefficient equals 0. approached significance (P=.0838). For low marbling potential ( low initial ether extract) cattle, Revalor tended t o  reduce marbling. For high marbling potential (high initial ether extract) cattle, Revalor may have had minimal effect (Figure 1). If a steer was black, marbling was increased by .19 units as compared to  steers categorized as other. The partial R2 for the variable black was .0148. To adequately test this model, a second independent set of data are necessary. This research is being repeated in 1994 t o  allow for a proper evaluation of the prediction equation. However, t o  illustrate the potential effectiveness of the model, the prediction equation was used to  sort cattle into high, moderate, and low marbling groups. Table 5 indicates that 85.2% of the cattle that were in the high predicted marbling group graded choice as compared to  52.7% and 43.6% grading choice for the I -' CONTROL REWLOR 1 3.6 I I I I I 0.6 1 1.6 2 2.6 3 3.6 ETHEREXTRACT 4.0 - SLlQHT 6.0 SMALL Figure 1. Interaction between Revalor and initial ether extract. Table 5. Marbling group as determined by prediction equationa Variable Low 113 Middle 113 High 113 Ether extract, % 1.38 * .030 1.72 k .026 2.12 * .036 Initial fat, in. .12 ,002 .13 * .004 .14 + .005 Marbling score unitsb 4.65 * ,059 4.84 * .086 5.30 i .081 Percentage choice 43.6 52.7 85.2 aMeans f standard error. b4.00 = slight0, 5.00 = small0. moderate and low groups, respectively. Percentage of choice for these categories were significantly different as determined by Chi square (P < .lo). For comparison, data were sorted only by coat color into black, red, and other categories (Table 6). Not as many high quality cattle were identified as with the prediction equation. However, Chi square analysis suggested this method was effective (P< .lo). The data were then sorted based on initial condition. Sixty-eight percent of the steers in the fat category graded choice compared with 53.6 and 56.5 for the thin and moderate categories, respectively (Table 7). These percentages were not significantly different (P> .lo) as determined by Chi square analyses, indicating that sorting by initial condition did not adequately identify high marbling cattle. In conclusion, ultrasound technology may be used to aid producers in making earlier marketing decisions and therefore may help alleviate some of the risks associated with value based marketing. However, additional research is needed to validate the prediction equation developed through this study. Table 6. Effect of coat color on percentage choicea Variable Black Red Other Ether extract, % 1.89 * .06 1.68 * .04 1.68 * .09 Initial fat, in. .14 i .005 .13 .003 .13 .006 Marbling score unitsb 5.2 * -10 4.8 * .06 4.7 * .15 Percentage choice 74.5 55.9 50.0 aMeans * standard error. b4.00 = slight0, 5.00 = small0. Table 7. Effect of initial fat thickness on percentage choicea Variable Thin Average Fat Ether extract, % 1.60 * -04 1.77 * .05 1.84 + .05 Initial fat, in. .10 * .001 .13 * .002 .16 + .003 Marbling score unitsb 4.75 k .071 4.89 & .094 5.11 & .082 Percentage choice 53.6 56.5 68.3 aMeans & standard error. b4.00 = slight0, 5.00 = small0. Acknowledqements We would like t o  thank Middle America Network from Mapleton, IA, for collecting the ultrasound images and the staff at Iowa State University for reading the images. 

Using Ultrasound Techonology in Incoming Feedlot Steers to Predict Marbling and the Effect of Anabolic Agents on Marbling

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Using Ultrasound Techonology in Incoming Feedlot Steers to Predict Marbling and the Effect of Anabolic Agents on Marbling

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