The prediction of bone weight in beef carcases using fore shanks weight and carcase measurements

Abstract

Animal Production in Australia 1998 Vol. 22 THE PREDICTION OF BONE WEIGHT IN BEEF CARCASES USING FORESHANKS WEIGHT AND CARCASE MEASUREMENTS G.E.M. MALELAKA and E.R. JOHNSONB A B Jln. Hati Mulia, Gg. IV/5 Oebobo, Kupang NTT 85111, Indonesia Division of Farm Animal Studies, The University of Queensland, P.O. Box 125, Kenmore, Qld 4069 SUMMARY The accuracy of prediction of weight and percentage of total side bone was examined in 361 carcases of cattle and calves, taking into account genotype, age and carcase weight. Hot carcase weight, carcase length and fat thickness at the 12th rib added to foreshanks weight gave significantly improved prediction over foreshanks weight alone. The weight and percentage of total side bone were predicted accurately in calves but not in adults as a non-defined group. Predictions in genotypes of adult carcases, using combinations of the above measurements were much more accurate than from using foreshanks weight alone. It is recommended that total side bone weight be predicted using all four independent variables. Separation of carcases into light (under 270 kg) and heavy (over 270 kg) groups did not improve the accuracy of prediction of total side bone. Keywords: prediction, bone weight, beef carcases INTRODUCTION Bone is generally a waste component of meat, but a knowledge of its weight or proportion will give a better indication of muscling. In a study of 80 Bos taurus steer carcases, Johnson (1979) showed that foreshanks weight (the weight of the clean, untrimmed foreleg beyond the carpo-metacarpal junction) was useful for predicting total side bone weight. The carcases studied showed a very wide weight range (49.7 to 382.3 kg) and side bone (mean, 14.4 kg) was predicted with a s.e.m. of 978 g and a correlation of 0.97. There was evidence that the use of side weight and fat thickness at the 10th rib, together with foreshanks weight, improved the prediction of total side bone weight. The limb bones of different genotypes of cattle grow at different rates (Kempster et al. 1977; Berg et al. 1978) and bone weight distribution, especially that of the distal limbs, may vary with genotype (Seebeck 1973; Truscott et al. 1976). Predictions of total side bone weight might improve in accuracy if corrections were introduced for genotype and carcase weight. In the following study, the prediction of total side bone (weight and percentage) was investigated in the carcases of 361 steer cattle and calves. Two hundred and sixty-eight of the animals were Bos taurus and 93, Bos indicus. Predictions were conducted in relation to genotype, carcase weight and age (adult-calf). MATERIALS AND METHODS The carcases of 289 adult steers and 72 calves, representing 11 breeds or types, were studied (Table 1). In this study, calves included animals from a few days of age up to ten months old. Measurements made on the carcases included hot carcase weight, foreshanks weight, carcase length (CT) and 12th rib fat thickness. Foreshanks was defined by Johnson (1979) as the two foreshanks disarticulated at the carpo-metacarpal junction, unskinned and cleansed of impacted faecal material and earth from sole and interdigital areas. The chilled right side of each carcase was totally dissected into its anatomical components. Data were analysed in age groups (adult-calf), breeds or breed types (within the adults) and carcase weight groups which consisted of two, light (up to 270 kg) and heavy (over 270 kg). Foreshanks weight was used alone and in multiple regression to predict the weight or percentage of side bone. In all Tables, foreshanks weight alone and the most accurate combination of predictors are shown. Criteria used to evaluate predictive performance were the s.e.m., coefficient of determination (R2), and tests of significance on the intercepts and slopes, among breeds and between age and carcase weight groups. RESULTS Table 2 shows the prediction of bone in adult and calf groups. In all carcases (adults and calves) and in adults, the prediction of side bone from foreshanks weight alone was improved by using three or four independent variables. However, for weight and percentage, the s.e.m. were high and for percentage prediction the coefficient of determination (R2) was low. 205 Animal Production in Australia 1998 Vol. 22 Table 1. Carcases studied in the prediction of total side bone Genotype Angus Brahman x Hereford Brahman Charolais crossbred Friesian Hereford Murray Grey Simmental x Hereford Ayrshire Jersey Guernsey TO T A L Adults 3 4 5 1 2 9 1 1 0 0 3 0 8 5 7 6 0 0 0 Calves 1 0 0 0 42 3 1 0 21 3 1 72 289 Table 2. Prediction of weight (kg) and percentage of total side bone in age groups Weight Group a Percentage R 2 Variables F/S F/S, CT, HCW, FT F/S F/S, CT, HCW, FT F/S FS, FT s.e.m. 3.10 2.70 3.44 2.89 1.28 1.18 Variables F/S F/S, CT, FT F/S F/S, CT, HCW, FT F/S F/S, CT, HCW, FT s.e.m. 3.62 3.35 2.89 2.80 2.35 1.72 R 2 All 361 Carcases (15.88) Adults (18.18) Calves (6.26) a 0.82 0.86 0.61 0.74 0.94 0.94 0.54 0.62 0.01 0.12 0.75 0.85 Value shown in parentheses for each group is mean total side bone weight (kg) F/S Foreshanks weight; CT Carcase length (After Yeates 1952); HCW Hot carcase weight; FT 12th rib fat thickness. In calves, both weight and percentage predictions were more satisfactory, especially the former. Using four independent variables, total side bone percentage in calves (mean 24.1; maximum 32.0) was predicted with a s.e.m. of 1.72. Relative to prediction in adults as a group, the prediction within genotypes improved greatly for both weight and percentage of total side bone (Table 3). Friesians were the only exception. In every genotype, the addition of hot carcase weight, carcase length or fat thickness, or all three, improved the accuracy of prediction from foreshanks weight alone, sometimes spectacularly. Weight prediction was more satisfactory in all genotypes except Simmental x Hereford. Percentage prediction was improved strongly by the addition to foreshanks weight of variables that accounted for carcase weight, size or fatness. The grouping of adult carcases into two groups, under and over 270 kg (Table 4) resulted in predictions that were far inferior to those given by genotypes, and no better than those given by all adults. DISCUSSION Johnson (1979) recommended the use of a prediction equation for total side bone weight in beef carcases, based on foreshanks weight, noting that carcase weight and fat thickness at the 10th rib tended to improve the prediction. This study extends those observations taking into account genotype, carcase weight and age group, and using the independent variables hot carcase weight, carcase length and 12th rib fat thickness. Although fat thickness and carcase weight are generally correlated, major variations in this relationship do exist (Ledger 1959; Mukhoty and Berg 1971; Charles and Johnson 1976). It was found that major improvements in the accuracy of prediction could be made by the use of a calf grouping and adult genotypes in which developmental differences were accounted for by the use of weight, size and fatness measurements. Although age grouping into adults and calves did not improve the accuracy of side bone predicted in the former group, it did in calves; here, for both weight and percentage predictions the s.e.m. were low, and the 206 Animal Production in Australia 1998 Vol. 22 Table 3. Prediction of weight (kg) and percentage of total side bone in genotypes Weight Group a Percentage R 2 Variables F/S F/S, HCW, CT F/S F/S, HCW, CT, FT F/S FS, HCW, CT, FT F/S F/S, CT, FT F/S F/S, HCW, CT, FT F/S F/S, HCW, CT, FT F/S F/S, HCW, CT, FT s.e.m. 3.71 1.72 1.39 0.92 1.59 1.29 0.87 0.46 2.27 1.73 4.11 3.45 0.74 0.51 1.30 1.30 Variables F/S F/S, HCW, CT, FT F/S F/S, HCW, CT, FT F/S F/S, HCW, CT, FT F/S F/S, CT, FT F/S F/S, HCW, CT, FT F/S F/S, FT F/S F/S, HCW, CT, FT F/S F/S, HCW, CT, FT s.e.m. 2.62 2.06 1.80 0.92 1.50 1.04 1.72 0.41 2.28 2.05 3.99 3.87 1.82 1.36 1.12 0.60 R 2 Angus (17.22) Brahman (18.87) BxH (20.35) MG (18.50) Hereford (16.66) Friesian (10.05) Char. x (18.28) 0.63 0.94 0.81 0.95 0.91 0.94 0.82 0.98 0.81 0.89 0.65 0.73 0.90 0.97 0.33 0.49 0.13 0.75 0.24 0.83 0.48 0.77 0.07 0.98 0.16 0.35 0.60 0.70 0.15 0.70 0.29 0.84 Simm x Her F/S (25.21) F/S, HCW, CT, FT a Value shown in parentheses for each group is mean total side bone weight (kg) B x H Brahman x Hereford; MG Murray Grey; Char. x Charolais crossbred; Simm x Her Simmental x Hereford F/S Foreshanks weight; HCW Hot carcase weight; CT Carcase length; FT 12th rib fat thickness. Table 4. Prediction of weight (kg) and percentage of total side bone in carcase weight groups Weight Group* Under 270 kg Over 270 kg Variables F/S F/S, CT, FT F/S F/S, HCW, CT, FT s.e.m. 3.24 3.04 3.14 2.78 R 2 Percentage Variables F/S F/S, HCW, CT, FT F/S F/S, HCW, CT, FT s.e.m. 3.58 3.43 1.96 1.86 R 2 0.38 0.47 0.23 0.42 0.01 0.16 0.01 0.14 R2 high. As industry improves its estimations of fat, muscle and saleable beef yield in carcases and cattle, there is likely to be a need to quantify bone more accurately. Cattle with light but functionally adequate bone have the potential, as carcases, to produce more protein and greater profit. Muscle-bone ratio has been recognised as an important carcase criterion for over 50 years (Hankins et al. 1943) but there is no simple method of measuring it. If this could be done, particularly in the calf, it would be invaluable. Muscle-bone ratio changes with growth but there is strong evidence that the relativity of the ratio in calves is maintained in the adult carcases (Berg 1968; Berg and Butterfield 1976). Should the selection of bone become important in the cattle and beef industries, it is obvious that its prediction needs to be done on the basis of genotype in order to obtain sufficient accuracy. In this respect, it is recommended that foreshanks weight be used together with the other three variables, hot carcase weight, carcase length and fat thickness and that weight of total side bone be predicted. Although P.B. ORourke (pers. comm.) and Johnson and Priyanto (1991) found the division of beef carcases into under and over 270 kg useful for the purpose of predicting saleable beef yield and estimated lean meat yield, these weight divisions were of no use for predicting total side bone (weight or percentage). 207 Animal Production in Australia 1998 Vol. 22 The prediction of total side bone in beef carcases may be improved greatly by evaluating calves as a group and adult cattle in their respective genotypes. In this latter group, corrections for carcase weight, carcase length and fatness will markedly improve the prediction of weight and percentage of total side bone, particularly the former. REFERENCES BERG, R.T. (1968). Growth and Development of Mammals. (Butterworth: London). BERG, R.T., ANDERSEN, B.B. and LIBORIUSSEN, T. (1978). Anim. Prod. 26, 245-58. BERG, R.T. and BUTTERFIELD, R.M. (1976). New Concepts of Cattle Growth . (University Press: Sydney). CHARLES, D.D. and JOHNSON, E.R. (1976). J. 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