Prediction of carcass composition and individual carcass cuts of Japanese Black steers

The objective of this study was to develop equations to predict carcass tissue weights and percentages and boneless carcass non-trimmed cut weights by using the cold carcass weight (CCW) and three other traits at the 6–7th rib section, which are routinely collected in carcass markets in Japan. Carcasses from 94 Japanese Black steers were used for the multiple regression analysis with a stepwise procedure and a novel Least Absolute Shrinkage and Selection Operator (LASSO). The accuracies of prediction (R²) and RMSEs for the carcass tissue and cut weights were similar between the two procedures. In contrast, LASSO appeared to be the better procedure for predicting carcass tissue percentages. The longissimus muscle area and subcutaneous fat thickness were the important predictors for the lean percentage in the stepwise procedure, and CCW was additionally selected when the LASSO procedure was used.     

Prediction of suckling lamb carcass composition from objective and subjective carcass measurements

Correlations and regression between fatness and carcass conformation measurements and carcass tissue composition has been studied for both sexes in suckling lambs, with slaughter weights between 9 and 15 kg. Objective fat measurements showed higher correlations than subjective fat measurements, mainly with carcass fat. Conformation measurements presented greater correlations with tissues weight than with tissues proportion (r0.50). CCW was highly correlated with total muscle in the carcass (R²=0.961). Two fatness measurements (KKCF proportion and dorsal fat thickness) were included for the prediction of the muscle proportion. Furthermore, the model included other measurements, such as fore cannon bone weight and internal carcass length although they displayed very low correlation coefficients. This equation explained 64.1% of the variation of carcass muscle proportion (r.s.d.=1.532). CCW was included in the prediction equations of tissue weights, although in the fat tissue equation it appeared in the form of the carcass compactness index (CCW/L). CCW was a good predictor of the weight of carcass tissues in suckling lambs, especially for muscle. Prediction equations for tissue composition in grams were more accurate (R²0.91) than those for tissue proportion. When gender was included in all models it did not improve either accuracy or precision of the prediction.     

Prediction of horse carcass composition using linear measurements

An analysis of meat quality performed on 107 horses showed that there are significant relationships between some linear measures of carcasses and the irrespective tissue contents. Thus, there is some potential for fat quantity estimation on the basis of nape fat thickness. The equation for the assessment of fat percentage in the carcass contains one variable, i.e., nape fat thickness only. However, even in this case the obtained multiple correlation coefficient was high, R=0.86 and the estimation error was at the level of 2.5%. As a consequence, the estimation of fat deposits in carcasses may be made more objective, and the measurement of nape fat thickness may be applied for the assessment of fat in the live animal.     

Prediction of carcass composition by impedance spectroscopy in lambs of similar weight

Previous research on impedance measurements for the prediction of carcass composition was predominantly carried out on animals that varied widely in body weight, breed, or sex. The high accuracy for the estimated lean or fat mass was mainly obtained by including the body weight in the regression equations. The objective of this study was the prediction of carcass composition in lambs of similar weight. We used 70 male German Merino Mutton lambs and 70 male German Blackheaded Mutton lambs with 35 and 45kg live weight each. Impedance measurements with different electrode placements were carried out in vivo and on carcasses 20min and 24h postmortem. The carcass composition was ascertained by dissection of the left carcass side into lean, fat, and bone. R(2)-values for prediction of lean mass by impedance and body weight ranged between 0.11 and 0.71 within breeds and weight groups and between 0.84 and 0.89in the total material. Lean percentage was estimated with R(2)=0.18-0.48 within breeds and weight groups. The corresponding values for the total material varied from 0.23 to 0.37. We conclude that the impedance method is not suitable for the prediction of lean or fat percentage, neither in lambs of similar weight nor in heterogeneous animals.     

Prediction of lamb carcass composition and meat quality using combinations of post-mortem measurements

Various post-mortem measurements (carcass weights, conformation and fatness classes, external carcass dimensions, eye muscle dimensions, subcutaneous fat depth, pH and temperature) were recorded on 197 Texel (TEX) and 200 Scottish Blackface (SBF) lamb carcasses. The potential use of these measurements to predict carcass composition and key meat quality traits was investigated, to enable categorisation of carcasses in the abattoir and/or for use in genetic improvement programmes. By combining different measurements, accurate predictions of dissected carcass muscle weight (adjusted R² 0.93 in TEX, 0.88 in SBF) and fat weight (adjusted R² 0.84 in TEX, 0.87 in SBF) were achieved, and moderate predictions of intra-muscular fat (adjusted R² 0.56 in TEX, 0.48 in SBF), whilst shear force was predicted with low to moderate accuracy (adjusted R² < 0.33 across breeds and cuts). Sex, eye muscle dimensions and subcutaneous fat depth improved predictions of carcass composition and intra-muscular fat, whilst pH or temperature provided little additional benefit for these traits, but increased prediction accuracies for shear force. These results could contribute to the development of automated carcass grading systems or help inform breeding decisions.     

Evaluation of live and carcass techniques for predicting beef carcass composition

Fifty beef animals varying in size, age and composition were used to determine the most accurate methods for determining beef composition. Separable and chemical composition of the 9-10-11th rib section and measurements of subcutaneous fat thickness were the most useful for explaining observed variability in carcass composition. For predicting percentage fat in fed steers, composition of the 9-10-11th rib section was the most accurate [coefficient of determination (R(2) 0·85)]. The 9-10-11th rib section was the most accurate and precise technique identified in this study to estimate beef carcass composition across and within all age classes. Specific gravity accounted for 68% of the variation in percentage of carcass fat across all age classes combined; however, specific gravity did not account for a significant portion of the variation within each age class. Deuterium oxide dilution was able to account for 77% of the variation in chemical fat percentage across all age classes combined; however, deuterium oxide dilution was not as effective in accounting for the observed variation in fat percentage within each age class. Ultrasound was found to be an accurate live measure of chemical fat percentage within all age classes combined.     

USDA yield grades and various carcass traits as predictors of carcass composition

Twenty-five carcasses from each of three breedtypes (Brahman, Angus and Brahman × Angus) were physically separated into fat, lean and bone. Several muscles from the round and the femur were used to derive equations to predict carcass composition and muscle-to-bone ratio. The femur (as a percentage of the carcass) was shown to predict percentage carcass bone with 90% accuracy. All of the muscles studied were highly related to total carcass lean but the percentage of carcass as M. biceps femoris was the best single muscle indicator of carcass lean of the muscles studied. More variation in carcass lean could be accounted for by a multiple regression equation, involving all four muscles studied, than by any single muscle. M. biceps femoris-to-femur ratio was found to predict carcass muscle-to-bone ratio with a high degree of accuracy. The USDA yield grades were found to be reliable indicators of carcass composition. A two-variable equation involving adjusted fat thickness and biceps femoris accounted for 88·6% of the variation (RSD = 1/·64) in percentage of carcass as separable lean.     

Effect of genetic origin, diet and weaning weight on carcass composition, muscle physicochemical and histochemical traits in the rabbit

Fifty rabbits originating from the crossing of one dam strain with three sire strains, Hy+, INRA 9077 and INRA 3889, were studied. The adult body weights of the sire strains were 5·1, 4·1 and 3·1 kg, respectively. After weaning, the Hy+ and the INRA 9077 rabbits were fed either an H (11·99 MJ DE kg DM⁻¹) or L diet (9·67 MJ DE kg DM⁻¹). The INRA 3889 rabbits were fed only the H diet. In each of these five blocks, two weaning weights were studied and the rabbits were slaughtered when the average body weight of each block reached 2·5 kg. Slaughter yield, carcass fatness and hindleg meat to bone ratio were determined. Muscular tissue was described using (1) physicochemical criteria (ultimate pH, L^*a^*b^* colour) of the biceps femoris (BFE), tensor fasciae latae (TFL) and semimembranosus accessorius (SMA) muscles and (2) histochemical characteristics of the longissimus lumborum muscle (LL) through computerised image analysis (fibre type composition, cross-sectional area). At slaughter, the rabbits of INRA 3889 sire origin, which had the highest degree of maturity (72%), gave the best slaughter yield (p<0·01), the heaviest reference carcass weight (p<0·01), and highest LL proportion (p<0·01), hindleg meat to bone ratio (p<0·05) and fatness (p<0·01); their LL muscle showed the lowest percentage of βR fibres, while the cross-sectional area of their muscular fibres was the highest (p<0·05). When all sire × diet combinations were put together, the heavier the weaning weight, the lower the daily gain (p<0·01) and the lightness (L*) of thigh muscles (p<0·05). The lower the DE content of the diet, the lower the growth rate, the slaughter yield, the reference carcass weight (p<0·01) and the cross-sectional area of all types of muscle fibres of the rabbits of both Hy+ and INRA 9077 sire origin.     

The relationship of carcass measurements to carcass composition and intramuscular fat in Spanish beef

Forty beef carcasses were classified for conformation and fatness. Besides, carcass weight, fat thickness (FT), carcass dimension, marbling by computer image analysis and ultrasound readings was recorded to complement grading. For predicting intramuscular fat (IMF) content, FT, number of intramuscular flecks and conformation increased R²-value from 0.19 to 0.64 compared to conformation alone. For visual marbling, ultrasound readings and thoracic depth (TD) increased the R²-value from 0.24 to 0.57 compared to fatness score (FS). The best variables for predicting weight of fabricated subprimals were carcass weight or compactness which is a function of carcass weight (R² between 0.94 and 0.63). Fatness score was poorer than FT for predicting yield of subprimals cuts from round (R² = 0.16 vs. 0.50) and ultrasound readings for less valuable subprimals (R² = 0.31 vs. 0.39). These results showed that other variables could be used in combination with carcass fatness or conformation to achieve a more accurate estimation of fat and carcass yield.     

Estimating beef carcass composition using the speed of ultrasound

The reciprocal of the speed of 2·25 MHz (nominal) ultrasound (RV) was measured at selected sites through the soft tissues of 72 beef carcasses from Friesian. Hereford and Hereford × Friesian bulls and steers at or within 1 h of stunning. The measurement sites were: through M. adductor horizontal to the caudal edge of the symphysis pubis (S2), through M. scalenus just cranial to the first rib (S3) and through M. longissimus thoracis between the tenth and eleventh ribs, approximately 6 cm from the midline (S4). The thickness of extractable lipid (d(f)) at each site was defined as the product βd, where β was the volume fraction of extractable lipid and d was the tissue thickness. The thickness of lipid-free tissue (d(ff)) was defined as (d-d(f)) and β was calculated from the ultrasonic measurements using an empirical linear relation between β and RV. When cold, the intact sides were scored independently for fatness and conformation by two experienced judges according to the EAAP system and their mean scores determined. Sides were split at the level of the last rib and the depth of subcutaneous fat measured at 25%, 50% and 75% of the width of M. longissimus thoracis from the midline. The three ultrasonic characteristics (RV, d(f) and d(ff)) at each site, the mean fat depth and the mean fat and conformation scores were examined for correlation with % fat and % lean in the sides determined by complete physical dissection. The best predictors of % fat were mean d(f) at S3 and S4, mean d(f) at S2, S3 and S4 and mean EAAP fat score which were all of comparable precision (rsd, respectively, 2·07, 2·06 and 2·08). The best predictors of % muscle were mean d(f) at S3 and S4, mean d(f) at S2, S3 and S4 and mean RV at S2, S3 and S4 (rsd, respectively, 1·79, 1·79 and 1·90). The corresponding residual standard deviations for mean EAAP fat score and mean fat depth were 2·18 and 2·20.     

Prediction of pork carcass composition based on cross-sectional region analysis of dual energy X-ray absorptiometry (DXA) scans

Dual energy X-ray absorptiometry (DXA) was used to measure pork carcass composition by performing a total scan of the right half of 262 pork carcasses (42.7±5.2 kg). The DXA scans were analyzed for percentage fat in the entire half-carcass as well as the shoulder, ham, loin, and side regions. In addition, a total of 14 cross-sections (57.6 mm wide) were analyzed: six in the shoulder/thoracic region, three in the loin region, and five in the ham region. Relative to the DXA measurement of total fat content, the coefficient of determination (R(2)) for a single cross-sectional slice ranged from 0.908 to 0.976. Relative to chemical analysis, a single slice from the ham region predicted the percentage of fat or lean in the half-carcass with an R(2) of 0.81 and a standard error of the estimate of 2.04. Prediction equations were used to analyze a separate group of 65 half-carcasses. These results indicate that carcass fat and lean percentages can be measured by performing a single-pass cross-sectional scan that would be compatible with on-line processing.     

Relationships between chemical composition and physically separated tissues of the pig carcass

Data from the physical and chemical dissection analysis of 50 Large White and 50 Hampshire × Large White carcasses, comprising equal numbers of gilts and castrates, slaughtered at 90 kg liveweight, are presented. The right-hand side of each carcass was dissected into lean, fat and bone and the combined tissues were then minced and chemically analysed for moisture, protein, ether extract and ash. Statistical relationships between the two methods of carcass analysis, except those between bone and ash, were not influenced by sex or breed type. Overall regression equations, i.e. ignoring sex and breed type, for the prediction of percentage lean from moisture, protein and ether extract percentages of the carcasses, had residual standard deviations of 1·26, 1·78 and 1·11, respectively, and corresponding values for the prediction of percentage carcass fat were 1·05, 1·68 and 0·74. Residual standard deviations for predicting percentages of moisture and protein in the carcass from percentage lean content were 1·07 and 0·46 and that for the prediction of percentage ether extract from fat percentage of the carcass was 1·20. Corresponding relationships between bone and ash percentages of the carcass were less satisfactory for predictive purposes.     

In vivo estimation of lamb carcass composition by real-time ultrasonography

The objective of this study was to evaluate the accuracy of ultrasonography to measure fat thickness in live lambs and predict carcass composition to find a system that can assess carcass composition easily and accurately, without damage to the product and can improve carcass classification. Fat thickness (FTh) between the 12th and 13th ribs and between the 3rd and 4th lumbar vertebrae, was measured in vivo using real-time ultrasound, in 67 Churra Galega Bragan?ana males (mean weight 36.0kg, range 21.5-47.0kg), using an ALOKA SSD-500V equipped with two probes (5 and 7.5MHz) in order to predict carcass composition. The most satisfactory correlation between carcass and ultrasound measurements was between the 3rd and 4th lumbar vertebrae fat thickness (FTh). The first variable admitted in the models to predict carcass composition (live weight, LW) explained between 63% and 96% of the total variation of the weight of the components of the carcass. In fact, 96% of the variation in total amount of muscle was accounted for by live weight. The inclusion of the ultrasound measures with the 7.5MHz probe improved, in all prediction equations, the coefficient of determination (R(2)) with a substantial reduction in the residual standard deviation (RSD). In relation to the subcutaneous fat of the carcass, 85% of the variation was explained by live weight and the FTh 12-13 7.5 measurement. In the prediction model for total carcass fat weight, live weight and ultrasound fat thickness measurement explained 88% of the variation. The results indicate that in vivo ultrasound fat thickness measures in association with live weight can be used to predict carcass composition in Churra Galega Bragan?ana lambs.     

The use of seemingly unrelated regression to predict the carcass composition of lambs

The aim of this study was to develop and evaluate models for predicting the carcass composition of lambs. Forty male lambs were slaughtered and their carcasses were cooled for 24 hours. The subcutaneous fat thickness was measured between the 12th and 13th rib and breast bone tissue thickness was taken in the middle of the second sternebrae. Left side of carcasses was dissected and the proportions of lean meat (LMP), subcutaneous fat (SFP), intermuscular fat (IFP), kidney and knob channel fat (KCFP), and bone plus remainder (BP) were obtained. Models were fitted using the seemingly unrelated regression (SUR) estimator which is novel in this area, and compared to ordinary least squares (OLS) estimates. Models were validated using the PRESS statistic. Our results showed that SUR estimator performed better in predicting LMP and IFP than the OLS estimator. Although objective carcass classification systems could be improved by using the SUR estimator, it has never been used before for predicting carcass composition.     

The use of ultrasound to predict the carcass composition of live Akkaraman lambs

The aim of this study was to measure fat thickness, area and depth of the longissimus dorsi muscle using ultrasonography, to estimate carcass composition in live Akkaraman lambs. Fat thickness, area and depth of the longissimus dorsi muscle between the 12th and 13th ribs were measured in vivo and on the carcass after slaughter, using real time ultrasound in 40 Akkaraman lambs. To estimate the carcass composition, one-half of a carcass was dissected into muscle, fat and bone after slaughter. Overall, correlation coefficients between ultrasound and carcass longissimus dorsi muscle area, depth and fat thickness were 0.82, 0.60 and 0.77, respectively. Estimates of carcass composition for Akkaraman lambs based on LW explained 78%, 82%, 74%, 52%, 75%, 36% and 72% of the variations for muscle, total carcass fat, subcutaneous fat, inter-muscular fat, non-carcass fat, tail fat and bone, respectively. The introduction of UFT, ULMA and ULMD as independent variables in addition to LW in the multiple linear regression equations further improved the variations for total muscle (80%), carcass fat (84%) and bone weight (76%) whereas no improvement was observed for subcutaneous, intermuscular, non-carcass and tail fat. The results showed that in vivo ultrasound fat thickness and measurement of area and depth of the longissimus dorsi muscle in association with live weight could be used to estimate muscle, total body fat and bone weight in Akkaraman lambs.     

Investigations into the accuracy of prediction of beef carcass composition using subcutaneous fat thickness and carcass weight I. Identifying problems

Investigations were conducted into the accuracy of prediction of the percentages of fat and muscle in 69 steer carcasses using subcutaneous fat thickness and carcass weight. The carcasses were arbitrarily divided into low and high fat thickness, and light and heavy weight categories. Relationships between fat thickness and the percentages of fat and muscle were modified by breed and weight group (or their interactive effects), or by breed and fat group (or their interactive effects). General equations ignoring breed should not, therefore, be used for prediction. The equations were modified by using low and high fat thickness or light and heavy carcass weight groups. Because of the absence of breed differences in the lighter weight and lower fat thickness groups, a single breed-ignored regression equation could be used in each case to predict the carcass components. In the fatter and heavier groups of carcass significant breed differences occurred and breed specific regression equations should be used.     

The use of seemingly unrelated regression to predict the carcass composition of lambs

The aim of this study was to develop and evaluate models for predicting the carcass composition of lambs. Forty male lambs were slaughtered and their carcasses were cooled for 24 hours. The subcutaneous fat thickness was measured between the 12th and 13th rib and breast bone tissue thickness was taken in the middle of the second sternebrae. Left side of carcasses was dissected and the proportions of lean meat (LMP), subcutaneous fat (SFP), intermuscular fat (IFP), kidney and knob channel fat (KCFP), and bone plus remainder (BP) were obtained. Models were fitted using the seemingly unrelated regression (SUR) estimator which is novel in this area, and compared to ordinary least squares (OLS) estimates. Models were validated using the PRESS statistic. Our results showed that SUR estimator performed better in predicting LMP and IFP than the OLS estimator. Although objective carcass classification systems could be improved by using the SUR estimator, it has never been used before for predicting carcass composition.     

Effect of feed protein on carcass composition and meat quality in steers

Forty-five Charolais steers were fed one of four experimental regimes containing maize silage and maize grain supplemented with either protected soyabean-rapessed meal or linseed meal. The first three regimes were formulated to supply the same energy and different protein levels with soyabean-rapessed meal: low (L-SRM), medium (M-SRM) and high (H-SRM). The fourth regime consisted in feeding the same amount (kg/day) of linseed meal as that of soyabean-rapessed meal in the H-SRM regime (LSM). As the protein level increased from L-SRM to H-SRM, the daily weight gain of steers increased and the carcass composition was changed towards higher muscle and lower fat proportions. Though the actual supply of feed protein by regime LSM was close to that achieved with M-SRM, the effect of linseed meal supplementation on weight gain and carcass composition was comparable to that obtained by feeding the high protein level (H-SRM). The dry matter content increased and the heme pigments and lipids contents decreased in longissimus thoracis muscle as the protein supply increased from the low to the high level. Again the amplitude of the differences in meat quality with L-SRM were similar in H-SRM and LSM. Muscle colour, connective tissue and mechanical strength remained practically unaffected by the protein treatments. However, meat was scored less tender in H-SRM and less juicy in treatment LSM than in treatment L-SRM. The results obtained with linseed meal suggest a specific effect of type of feed protein on beef carcass composition and meat quality.     

In vivo prediction of carcass composition and muscularity in purebred Texel lambs

A subjective assessment of the shape of the hind limb of purebred Texel lambs was evaluated as an in vivo predictor of carcass composition and muscularity. Lambs were taken from two flocks that were managed in a common environment, but which had either been selected for lean tissue growth rate or for improved conformation. Lambs were slaughtered at a mean age of 139 days at the end of an 11 week performance test in which they were reared indoors on a concentrate diet. Pre-slaughter measurements of live weight and ultrasonic muscle (UMD) and fat (UFD) depths at the position of the third lumbar vertebra, body length (L) and a subjective leg shape score were recorded. After slaughter, measurements were recorded for carcass side length (SL), leg length (T) and the maximum width (A) and depth (B) of the longissimus thoracis and lumborum (LTL) muscle. The side was fully dissected and various muscle weights and skeletal dimensions were used to calculate indices of muscularity as √(muscle weight/length) per unit length or as UMD/L, A/SL or B/SL. The leg shape score was positively correlated with lean weight (0.23) and proportion (0.24), lean:bone ratio (0.25), measures of LTL dimensions (0.27-0.38) and muscularity traits (0.27-0.57) but was not significantly (P>0.05) correlated with fat weights or proportions in the carcass. Live weight was the best single predictor of lean weight (RSD=0.403) and the addition of leg shape score (RSD=0.381) to prediction equations was less effective than the inclusion of UMD and UFD in combination (RSD=0.357). The addition of leg shape score to equations that included ultrasonic traits gave a significant (P<0.05) but marginal improvement in prediction (RSD=0.347). The leg shape score was the most useful in vivo predictor of carcass muscularity traits and, with R(2) in the range 0.30-0.50, had comparable predictive power to a leg muscularity score derived from muscle weight and femur length. It is concluded that the leg shape score showed potential as a predictor of carcass muscularity that was largely independent of live weight and fatness at a fixed age and was marginally associated with superior lean yield and lean:bone ratio.     

The prediction of beef carcass composition: A comparison of models

Any attempt to summarise existing knowledge on the prediction of carcass composition without detailed dissection is bedevilled by the variety of methods used by different workers, not least in the analysis and presentation of their results. This paper examines one cause of the apparent confusion: the differences in interpretation arising from the use of different regression models in allowing for the effect of variable live weight or side weight. The part/whole relationships implied in examining the effect of a total weight on the weight of a part are considered, and by applying four regression models to two sets of published data, it is hoped to facilitate reconciliation of the conflicting results reported in the literature.