Implant and biological type effects on beef carcass characteristics

Meat Science, Vol. 41, No. I, pp. 47-53, 1995 Copyright 0 1995 Elswier Science Limited Printed in Great Britain. All rights reserved 0309-1740/95 59.50+0.00 ELSEVIER

0309-1740(94)00050-6

Implant and Biological Type Effects on Beef Carcass Characteristics

C. R. Kerth,

Animal

M. F. Miller,* B. L. Owen, B. H. Brophy dz C. B. Ramsey

Science and Food Technology Department, Texas Tech University, Lubbock, TX 79409-2162, USA? (Received

15 June 1994; revised version received accepted 2 September 1994)

28 August

Box 42162,

1994;

ABSTRACT Beef carcasses (n = 1574) were evaluated at Excel Corp. beef slaughtering facility, Friona, Texas, to determine the effects of implants (double Rev&or and Ralgro/Revalor) and biological type (Continental European, Continental European X British and British) on carcass characteristics. No differences (P > 0.05) were found between implants for marbling score, USDA quality grade, adjusted preliminary yield grade, percentage kidney, pelvic and heart fat, or carcass weight. Carcasses from cattle implanted with double Revalor had a larger (P c 0.05) ribeye area and a lower USDA yield grade. No dt&Terences were found among breed types for marbling score, USDA quality grade, preliminary yield grade, ribeye area or USDA yield grade (P > 0.05). Steers classed as continental European had the lowest adjusted preliminary yield grade and percentage kidney, pelvic and heart fat, the heaviest carcasses and were most muscular as determined by the Excel muscle score (P < 0.05).

INTRODUCTION Implants have been used widely in beef production as one of many technologies to maximize rate of gain and feed conversion. Various schemes of reimplanting the same or different implants, with reimplanting time based on the manufac*To whom correspondence should be addressed. tMention of a trade name, proprietary product or specific equipment is necessary to report factually on available data; however, Texas Tech neither guarantees nor warrants the standard of the product, and the use of the name by Texas Tech implies no approval of the product to the exclusion of others that may also be suitable. 47

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C. R. Kerth et al.

turer’s recommended efficacy period, have been used to achieve the greatest benefit. However, growth response to reimplanting has been variable. Research with diethylstilbestrol implants indicated that response to reimplanting depended on the length of the initial implant period (Bell et al., 1960; Essig, 1961; McCormick et al., 1961; Melton & Riggs, 1965; Hale et al., 1972; Rumsey et al., 1978; Byers, 1979). Of 26 comparisons, eight involved an average initial period of 70 days and a reimplant period of 70 days, nine involved an initial period of 118 days and a reimplant period of 139 days, and nine involved an initial period of 147 days and a reimplant period of 123 days. Reimplanting increased gains by 4.5, 17.2, and 16.4% respectively. Diethylstilbestrol implants were absorbed over a period of 170 days; 29% of the original implant remained at 60 days and 17% at 120 days (Rumsey et al., 1978). In addition to increases in gain, growth promoters reduce fat thickness, percentage of internal fat, USDA yield grade number, marbling and USDA quality grade while increasing carcass weight, conformation score, and ribeye area (Galbraith et al., 1981; Rumsey, 1982; Lomas, 1983; Trenkle, 1987, Apple et al., 1991). In addition to growth promoters, continental European (CE) breed types have been used in the United States to increase gain and feed efficiency. Ferrell et al. (1976) found that CE breed types had a higher rate of gain, leaner carcasses, larger longissimus area, and higher cutability, but had less marbling compared to British and British cross breed types. The purpose of this study was to evaluate the effects of implant and breed type on carcass characteristics.

MATERIALS

AND METHODS

Implant treatment Thirteen lots of beef steers (n = 1574) were fed at Caprock Feeders, Bovina, Texas, a high energy diet composed of 35% high moisture corn, 35% flaked milo, 20% corn silage, 3% alfalfa hay, 4.2% protein supplement, 0.3% salt and 2.5% trace mineral mix. Time in the feedlot ranged from 13 1 to 196 days (Table 1). Upon arrival, one-half of the steers were implanted with Ralgro (a growth promoting implant containing natural estrogen) and the other half were implanted with Revalor (a growth promoting implant containing a synthetic androgen and 24 mg P-estradiol.) After the steers had been on feed about 90 days, all steers then were implanted with the Revalor implant. Pens were shipped to the slaughter plant when the weight of the steers in the various pens averaged 577-623 kg. Carcass evaluation Beef carcasses were evaluated to determine the effects of implants (double Revalor and Ralgro/Revalor) and biological type (CE, which consisted of Simmental, Limousin, Maine Anjou, Salers, etc.; British, which consisted of Angus, Hereford, Shorthorn, etc.; and CE X British) on carcass characteristics. Trained and experienced personnel from Texas Tech University evaluated the carcasses

49

Implant and biological type eflects

at the Excel Corp. beef processing facility in Friona, Texas. Carcasses were evaluated for skeletal and lean maturity, USDA marbling scores, adjusted fat thickness, ribeye area, kidney, pelvic and heart fat percentage, hot carcass weight and Excel muscle score. Excel muscle score is a visual appraisal based on ribeye area, round muscle plumpness, and weight. Scores range from 1 to 5 with 1 having the most muscling and 5 having the least. USDA quality and yield grades then were determined. Data analysis The data were analyzed using a 2 (implant) X 3 (biological type) factorial arrangement of a completely randomized design and summarized according to the procedures outlined by the Statistical Analysis System (SAS, 1991). Mean separation was conducted by utilizing the probability differentiation of least squares means procedure when a significant main effect occurred. The predetermined acceptable statistical probability level was 5%. No interactions were calculated because of the absence of the British breed type in the Ralgro/Revalor implant treatment. Percentages of carcasses in yield and quality grade and fat thickness ranges were calculated.

RESULTS Feedlot data Means for feedlot performance data by lot are presented in Table 1. These data were not statistically analyzed because individual steer data were not collected. TABLE 1 Feedlot Data” by Lots within Kind of Implant and Biological Type of Cattle

Kind of implant

Cattle Lot type number

Double Revalor CEb CEX British British Ralgro/Revalor

CE

CEX British

5030 5065 5048 5053 5050 5055 5054 5056 5068 5069 5041 5064 5076

No. of steers

No. dead

138 179 99 59 125 140 74 98 95 193 93 187 183

2 1 1 1 0 0 0 0 1 0 0 1

1

Days on In weight, Out feed (kg) (kg)

196 159 156 159 162 158 159 151 144 131 168 138 131

316 360 337 345 350 352 371 380 372 386 337 400 401

599 592 569 568 581 581 596 606 577 578 599 623 600

Feed ADG, consumed,

DM

(kg/day) (kg/day) (conv.,kg)

1.45 1.41 1.45 1.36 1.45 1.45 1.41 1.50 1.45 I.50 1.59 1.63 1.54

13.15 13.90 13.74 12.62 13.74 14.78 13.97 15.09 14.34 14.87 14.05 15.08 15.01

“Data were not statistically analyzed because individual steer data were not collected. bContinental European.

2.9 3.1 3.0 2.9 3.0 3.2 3.1 3.2 3.1 3.2 2.9 2.9 3.2

C. R. Kerth et al.

50

TABLE 2 Means for the Effects of Kind of Implant on Carcass Traits Carcass trait

Marbling score’ USDA quality gradeb Preliminary yield grade Adj. preliminary yield grade Ribeye area, cm2 Kidney, pelvic & heart fat (%) Carcass weight (kg) USDA yield grade Excel muscle scorer

Double Revalor 489

18.0 3.16’ 3.35 88.69’ 1.55 380.5 2.46d 2,4d

Ralgro/Revalor

493 18.0 3.09d 3.34 86.43d 1.58 384.4 2.59e 2.5’

“400 = Slight”“, 500 = Small”“.

‘16 = Selectt, 18 = Select+. “A lower muscle score indicates greater thickness of muscling. “‘Means in a row with the same or no superscript do not differ (P > 0.05).

TABLE 3 Effects of Kind of Implant on Quality Grade, Adjusted Fat Thickness and Yield Grade Percentages Grade of fatness

Double Revalor (76)

RalgroIRevalor (%)

USDA quality grade Choice Choice+ Choice’ ChoiceSelect Select+ SelectStandard or lower

50.0 0.1 1.0 48.9 48.3 26.2 22.1 1.7

1.1 50.9 45.1 21.8 23.3 2.4

Fat thickness, cm” 10.51 0.51-0.99 1.0&1.50 1.51-2.00 2.01-2.50 22.51

0.1 10.7 51.1 33.2 4.3 0.6

0.1 12.1 54.8 30.3 1.8 0.9

USDA yield grade 1 2.0-2.4 2.5-2.9 3.0-3.4 3.5-3.9 4 5

24.1

23.8 23.8 17.5 8.1 2.3 0.4

16.6 23.4 31.2 19.7 7.5 1.4 0.2

52.5 0.5

“Fat thickness is adjusted for fat deposits at locations other than over the ribeye.

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Implant and biological type effects

Implant treatment

Kind of implant did not affect (P > 0.05) marbling score, USDA quality grade, adjusted preliminary yield grade, percentage kidney, pelvic and heart fat, and carcass weight (Table 2). Steers implanted with double Revalor had a higher (I’ < 0.05) preliminary yield grade, indicating more fat over the 12th rib, than steers implanted with RalgroRevalor. However, carcasses from cattle implanted with double Revalor had a larger mean ribeye area and a lower USDA yield grade, indicating higher cutability (P < 0.05). The Ralgro/Revalor implant treatment produced carcasses with a higher (P < 0.05) Excel muscle score, indicating that they were slightly less muscular. Thus, cattle implanted with double Revalor showed slightly more muscle development and higher estimated cutability than those implanted with Ralgro/Revalor. Cattle implanted with double Revalor had 2.5% fewer carcasses that graded Choice but 3.2% more that graded Select than cattle given the Ralgro/Revalor implant (Table 3) although the means were not different for USDA quality grade (both were high Select, Table 2). Over 97% of the carcasses that graded Choice were Low Choice (Table 3). In contrast, Select grade carcasses were nearly evenly divided between High and Low Select. Cattle implanted with Ralgro/Revalor had 5% more carcasses with s1.5 cm of fat cover over the ribeye (67 vs 62Y0). However, the means for adjusted fat thickness were not different (1.36 vs 1.37 cm, P < 0.05) between implant treatments. Although more of the Ralgro/Revalor implanted steers had 1.5 cm of fat thickness, 8% fewer had yield grades below I 2.4. The heavier carcass weights and smaller ribeyes of the Ralgro/Revalor-implanted cattle were responsible for these results. Breed type treatment

No differences were found among breed types for marbling score, USDA quality grade, preliminary yield grade, ribeye area or USDA yield grade (P > 0.05, Table 4). TABLE 4 Means for the Effects of Biological Type of Steers on Carcass Traits Carcass trait

CE

CE X British

British

Marbling score” USDA quality grade“ Preliminary yield grade Adj. preliminary yield grade Ribeye area, cm*

486 180 3.15 3.31d 88.37

491 18.1 3.17 340’ 89.01

491 17.9 3.17 3.W 88.37

Kidney, pelvic & heart fat (%) Carcass weight (kg) USDA yield grade Excel muscle score

1.48d 39o.Y 2.50 2,3d

1.63’ 370.6d 2.42 2.5’

1.62’ 379.7’ 2.55 2.6’

“400 = Slight”“, 500 = SmalP’. b16 = Select-, 18 = Select+. ‘A lower muscle score indicates greater muscle thickness. defMeans in a row with the same or no superscript do not differ (P > 0.05).

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C. R. Kerth et al.

TABLE 5 Effects of Biological Type of Steers on Quality Grade, Adjusted Fat Thickness and Yield Grade Percentages Grade or fat thickness

CE (95)

USDA quality grade Choice Choice’ Choice’ ChoiceSelect Select+ SelectStandard and lower

52.8 0.4 I.1 51.3 45.8 25.4 20.4 1.4

49.1 0.2 1.2 48.8 47.1 21.5 25.6 2.8

51.0 0.4 0.8 49.0 47.0 24.3 22.1 2.0

0.3 12.8 54.6 28.5 3.8 0.1

0 10.5 55.2 31.3 1.5 1.5

0 10.0 44.2 41.4 3.6 0.8

19.4 22.3 28.0 20.0 9.0 1.2 0.1

19.6 25.5 29.3 17.5 5.8 2.2 0.2

21.9 22.7 24.7 17.9 8.8 2.8 1.2

Fat thickness, cm’ 10.51 0.51-0.99 [email protected] 1.51-2.00 2.01-2.50 12,51 USDA yield grade 1 2.0-2.4 2.5-2.9 3.0-3.4 3.5-3.9 4 5

CE X British (“/I)

British (%)

“Fat thickness is adjusted for fat deposits at locations other than over the ribeye.

Steers classed as CE had the lowest adjusted preliminary yield grade, the lowest percentage kidney, pelvic and heart fat, the heaviest carcasses and were most muscular as determined by the Excel muscle score (P < 0.05). The data show that the CE’s tended to be less fat, heavier and more muscular than the other two breed types. The only notable difference among cattle types in USDA quality grade distribution was that 6.6% more crossbred steers graded Low Select or lower than did the CE steers. The British cattle type had 458% of their carcasses with ~1.5 cm of fat thickness compared to 34.3% for CE X British crossbreds and 32.4% for the CE type. More of the CE carcasses (74.4%) yield graded 1 or 2 than carcasses from CE (69.7%) and British cattle types (69.3%). The British cattle type had the most (4.0%) USDA yield grade 4s and 5s.

DISCUSSION In recent years, consumers have been demanding beef that has less external fat, and in 1992, persons conducting the National Beef Quality Audit (NBQA)

Implant and biological type eflects

53

surveyed purveyors, restaurateurs and retailers about their top 10 concerns. All three groups responded that their number one concern was excessive external fat. Therefore, it is imperative that the beef industry take steps that will reduce external fat without reducing intramuscular fat that is important for maintenance of acceptable tenderness and flavor in beef (Berry and Leddy, 1990). According to the NBQA, 35% of cattle that graded Choice and 52% of cattle that graded Select were USDA yield grade 2.75 or lower (numerically). Comparatively, about 44% of all cattle in this study had a USDA yield grade of 2.5 or less. So it seems that the cattle in this study are distributed similarly to the NBQA with respect to yield grade. The NBQA also reported that in 1991, 37% of the cattle tested graded Select and 53% graded Choice. In comparison, in this study, about 48% graded Select and 51% graded Choice. These figures are lower than the ‘ideal mix’ that the NBQA reported as 29% Select and 64% Choice. The most apparent differences were in breed types. Marbling scores did not differ across the three breed types, but the CE breed type showed an advantage in being less fat and having a higher estimated cutability. Overall, about onethird of all the cattle in this study had 1.5 cm or more of fat thickness over the ribeye. This fatness probably was due to the cattle remaining on feed for as long as 196 days. Therefore, double Revalor implants can be successfully used to increase muscling and cutability in feedlot steers, and the greatest effect should be found when CE type cattle are implanted by the double Revalor method.

REFERENCES Bell, T. D., Danmen, J. J. & Wells, W. (1960). Idaho Agric. Exp. Sta. Bull., 334. Berry, B. W. & Leddy, K. F. (1990). J. Anim. Sci., 68, 666. Byers, F. M. (1979). Ohio Beef Cattle Res. Rep., Anim. Sci. Series, 79-1, 83. Essig, H. W. (1961). Mississippi State Univ. Agric. Exp. Sta. Tech. Bull., 48. Ferrell, C. L., Kohlmeier, R. H., Grouse, J. D. & Glimp, H. (1978). J. Anim. Sci., 46, 255.

Hale, W. H., Theurer, B., Ray, D. E., Marchello, J., Taylor, B. & Belew, M. (1972). Univ. of Arizona Agric. Exp. Sta. Cattle Feeders’ Day. Series P-26.

McCormick, W. C., Hale, 0. M. & Southwell, B. L. (1961). Georgia Agric. Exp. Sta. Tech. Bull., 23, 5.

Melton, A. A. & Riggs, J. K. (1965). 5-l 1. Texas Agric. Exp. Sta. Bull., B-1035, 5. National Beef Quality Audit. 1992. Executive Summary National Beef Quality Audit. National Cattlemen’s Assoc. in coordination with Colorado State Univ. and Texas A&M Univ. Rumsey, T. S. (1978). J. Anim. Sci., 46, 463. SAS (1991). SAS User’s Guide: Statistics. Statistical Analysis Systems Inst. Inc., Gary, NC, U.S.A.