Use of linear measurements of m. longissimus to predict the muscle content of beef carcasses

Five linear measurements associated with the eye muscle (m. longissimus), together with hot carcass weight, 10th rib fat thickness, eye muscle area and an estimate of eye muscle volume (eye muscle area × a carcass length measurement) were made on 53 chilled beef carcasses (hot weight 143-384 kg). The right side of each carcass was anatomically dissected into muscle, bone, fat and connective tissue. Correlation and regression analyses were used to identify the most accurate predictors of weight and percentage of side muscle. In simple regression, hot carcass weight and the estimate of eye muscle volume were the most accurate predictors of side muscle weight; 10th rib fat thickness and MN, a depth measurement of muscle and fat over the loin, were the most accurate predictors of percentage side muscle. In multiple regression, the addition of either eye muscle volume or eye muscle area to hot carcass weight and 10th rib fat thickness gave the most accurate predictions of side muscle weight and percentage side muscle, but in the case of each dependent variable, the improvement in accuracy was slight compared with that of the two most accurate regressors, hot carcass weight and 10th rib fat thickness. Although eye muscle volume was a more accurate predictor of side muscle weight than eye muscle area in simple regression, their contributions in multiple regression with hot carcass weight and 10th rib fat thickness were similar. None of the five linear measurements associated with m. longissimus contributed significantly to improving the prediction of weight or percentage of side muscle.     

The value of carcass weight, fat depth measures and eye muscle area for predicting the percentage yield of saleable meat in Australian grass-fed beef carcasses for Japan

The percentage saleable meat yield was determined for 42 carcasses from grass-fed steers representing a range of breed types purchased in Australia for the Japanese market. Their mean (s.d.) carcass weight and P8 fat depth were 329 (28.1) kg and 17.3 (4.3) mm, respectively. All measures of subcutaneous fat depth were significantly (P < 0.05) and moderately correlated with percentage saleable meat yield, with measures in the loin region showing a stronger association than those taken in the rump region. The association between P8 fat depth and the loin measures of subcutaneous fat were low and there was a significant (P < 0.05) association only between P8 and fat depth at the 10th rib (FD 10). The use of fat depth measurements from the loin region reduced the error associated with predicting saleable meat yield more than those from the rump region and significantly increased the amount of variation (R(2)) in saleable meat yield that was explained. Hot carcass weight (HCW) did not significantly (P > 0.05) improve prediction models when combined with subcutaneous fat depth measurements and overall, the R(2) values were low ranging from 0.19 to 0.42. The models indicated that fat depth measures and carcass weight are poor predictors of percentage meat yield in heavy-weight carcasses from mixed breed cattle as produced and processed in Australia. The prediction of percentage yield was in general significantly (P < 0.05) improved when measures of M. longissimus thoracis et lumborum (LD) area were added as independent variables to models based on hot carcass weight and subcutaneous fat depth measurements. With LD area added the amount of variation in yield that could be explained by the models increased by as much as 28%. Overall, the best model was based on fat depth at the 12th rib and LD area measured at the 5th rib for which the R(2) was 0.58 and the residual standard deviation was 1.63%. The next most accurate prediction of yield was provided by a model which included the independent variables used in the Australian Chiller Assessment Scheme namely HCW, FD10 and LD area at the 10th rib upon which breed type had no significant (P > 0.05) effect.     

Sheep carcass composition estimated from Longissimus thoracis et lumborum muscle volume measured by in vivo real-time ultrasonography

The use of Longissimus thoracis et lumborum muscle (LM) volume measured in vivo by real-time ultrasonography (RTU) to estimate carcass composition was evaluated in 47 female sheep. Animals were scanned over six sites (7th, 9th, 11th and 13th thoracic vertebrae and 2nd and 4th lumbar vertebrae). After slaughter carcass weight (CW) and composition by dissection were determined. RTU volume measurements were calculated by multiplying the LM area at each site by the vertebra lengths. Equivalent measurements to those taken in vivo were obtained on the carcass using a digital camera and image analysis. The correlation between LM volume measured by RTU and in the carcass was high for all scans. LM volume was better in predicting carcass muscle than carcass fat. Lower determination coefficients were obtained between LM volume and carcass tissues expressed in % of CW. The best estimates of carcass tissues weights and proportions were obtained using the LM volume between the 2nd and the 4th lumbar vertebrae for all tissues.

Multiple regression equations were fitted using live weight (LW) and LM volume to predict carcass composition. For all tissues, the best fit was obtained with two, three or four independent variables and the stepwise procedure was consistent in selecting LW to establish the prediction equations. Weights and proportions of muscle, subcutaneous fat, intermuscular fat and total fat were accurately predicted.

These results indicate that Longissimus thoracis et lumborum muscle volume measured in vivo by RTU can be used to predict sheep carcass composition (muscle and fat).     

A novel approach to grading pork carcasses: computer vision and ultrasound

A Computer Vision System prototype for grading pork carcasses was developed at the Lacombe Research System. The system consists of two components: ultrasound imaging to scan a cross-section of the loin muscle and video imaging to capture two-dimensional (2D) and three-dimensional (3D) images of the carcass. For each of the 241 carcasses (114 barrows and 127 gilts), salable meat yield was determined from a full cutout. Linear, two- and three-dimensional, angular and curvature measurements and carcass volume were derived from each image. Muscle area and fat thickness (7 cm off the mid-line) measured by ultrasound at the next to last rib site, together with 2D and 3D measurements provided the most accurate model for estimating salable meat yield (R²=0.82 and RSD=1.68). Models incorporating fat thickness and muscle depth measured at the Canadian grading site (3/4 last rib, 7 cm off the mid-line) with the Destron PG-100 probe, had the lowest R² and highest residual standard deviation (RSD) values (R²=0.66 and RSD=2.15). Cross-validation demonstrated the reliability and stability of the models; hence conferring them good industry applicability. The Lacombe Computer Vision System prototype appears to offer a marked improvement over probes currently used by the Canadian pork industry.     

Interrelationships amongst carcass and meat quality characteristics of sheep

The relationships between various carcass and meat quality characteristics of sheep were studied. Relationships were determined by regression, using data obtained from sheep belonging to a wide range of breeds, sex types and slaughter weight (32-62 kg). The chilling rate of the M. longissimus dorsi (LD) post-mortem was negatively correlated with carcass weight (r=-0.42, P<0.01), back fat thickness (r=-0.54, P<0.001) and the cooking loss of the M. infraspinatus (IS) muscle (r=-0.44, P<0.001). Correlation between chilling rate and shear force of the IS muscle was not significant, which was also the case between chilling rate and the cooking loss and shear force of the LD and M. triceps brachii muscles. A positive relationship was observed between total collagen and cooking loss (r=0.34, P<0.05) and between heat-insoluble collagen and cooking loss of the LD muscle (r=0.37, P<0.01). Generally collagen content was positively correlated with lean content and negatively with fat content. Carcass weight was significantly (P<0.001) correlated with intramuscular fat (r=0.61), moisture (r=-0.76), cooking loss (r=-0.49), shear force (r=-0.41) and hue angle (r=-0.41). Shear force was positively associated with cooking loss (r=0.42, P<0.001), but negatively with intramuscular fat content (r=-0.55, P<0.001). Cooking loss was positively correlated with moisture content (r=0.55, P<0.001).     

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.     

Prediction of lean and fat composition in swine carcasses from ham area measurements with image analysis

Video images of ham cross-sections were recorded from 71 pork carcasses (ranging in weight from 72 to 119 kg). Three sets of prediction equations were developed to estimate pork carcass lean and fat composition from video image analysis (VIA) of ham cross-sectional area measurements, 10th rib back fat depth (TENFAT) and hot carcass weight (HCKg). Carcass data of dissected lean and fat in the four primal cuts (ham, loin, Boston button and picnic shoulder) were used as dependent variables in establishing regression equations. The first set of equations combined VIA ham measurements and total ham weight (HTKg). Regression models containing the single variable HTKg times ham percentage lean area (Vol. 1) or HTKg times ham percentage fat area (Vol. 2) accounted for 88% and 68% of the variation in total carcass lean weight (CLKg) and total carcass fat weight (CFKg) from the right side of each carcass, respectively. The second set of equations combined VIA ham measurements and TENFAT (cm). Multiple regression models involving TENFAT, Vol. 1, and Vol. 2 accounted for 91% and 90% of the variation in CLKg and CFKg. The third set of equations used VIA ham measurements, TENFAT and HCKg. Carcass lean weight was best predicted by HCKg, TENFAT, and ham lean area (HLA) (R² = .92). Carcass fat weight was best predicted by HCKg, TENFAT, and Vol. 2 (R² = .91). Overall correlations showed a high association between Vol. 1 and CLKg (r = .94, P < .0001) and Vol. 2 and CFKg (r = .83, P < .0001). Ham lean area was related to CLKg (r = .74, P < .0001) and ham fat area to CFKg (r = .81, P < .0001). The results of this study indicated video image analysis of ham cross-section slices combined with backfat depth at the 10th rib can be used for accurate estimation of total carcass lean or fat composition.     

Relationships of fat-tail dimensions with fat-tail weight and carcass characteristics at different slaughter weights of Torki-Ghashghaii sheep

The purpose of this research was to investigate the relationship between fat-tail and carcass attributes in Torki-Ghashghaii sheep. Thirty ram lambs belonging to six weight groups (weighing from 25 to 50kg) were used. Fat-tail measurements were recorded on the live animals before slaughter. Hot and cold (after 24h in the cold room) carcass weights, and the weights of the tail and internal organs were recorded. The carcass was dissected into conventional cuts. Each cut was de-boned and the physically separable fat was removed from the meat. The bone, physical fat and trimmed meat were weighed separately. The weight of trimmed meat as a percentage of slaughter weight did not change significantly from 25 to 50kg live weights (23.4-25.3%). The weights of physically separated fat and the fat-tail as a percentage of live weight varied from 6.6% to 15.5% for various weight groups. The correlation coefficients between the tail weight and dimensions were large, positive, and significant. The highest correlation coefficient was found between the tail weight and upper circumference (r=0.88), and the lowest one was found between the tail weight and upper thickness (r=0.61). The upper and lower circumferences of the tail accounted for 85% of the total variation in the tail weight. The tail weight was positively correlated with the meat chemically determined fat (ether extract; r=0.43; P<0.05) and with the total body fat (r=0.70; P<0.01). Further studies are needed to see whether inclusion of fat-tail measurements in breeding programs would result in a decrease in body fat in this breed.     

Estimation of the carcass composition of yearling bulls of "Asturiana de los Valles" breed from the dissection of a rib joint

To evaluate different methods of estimating bovine carcass composition, seventy yearling bulls of the "Asturiana de los Valles" beef breed were slaughtered and their carcass composition estimated by a commercial dissection of the right half-carcass and by tissular dissection of the 6th and 10th rib of the left half-carcass. Correlation and regression analyses were used to identify the most accurate predictors of carcass composition. In simple regression, the percentage of lean in the 10th rib was the most accurate predictor (r=0.88; P<0.001) of the lean proportion in the carcass and the percentage of fat in the 6th rib was the best predictor (r=0.90; P<0.001) of the carcass fat content. The correlation coefficients for estimating the bone percentage in the carcass from the bone proportion in the ribs (6th and 10th) were low (r=0.63 and 0.51 respectively), although significant (P<0.001) and the coefficient improved when the proportion of lean in the ribs was used as predictor (r=0.78 and 0.70 for the 6th and the 10th rib respectively). In multiple regression, the addition of more regressors of the rib composition and carcass traits, such as carcass hot weight, the carcass fatness score and the weight of the kidney knob and channel fat, led to an improvement (P<0.05) in accuracy for some predictions. The results in general show that the accuracy of the predictions for the carcass composition obtained from dissection of both the 6th and 10th ribs was similar, although the dissection of the 10th rib tended to overestimate the proportion of fat in the carcass. Therefore, considering the carcass quartering method for the extraction of the ribs, it is proposed that dissection of the 6th rib is more appropriate than dissection of the 10th rib so as not to reduce the carcass value and obtain a good estimate of the carcass composition.     

Muscle: Bone ratios in beef rib sections

Thirty-eight steers and thirty heifers (14 to 17 months of age, from F(1) Hereford × Brahman cows bred to Angus or Hereford bulls), were either forage-fed for 123 days on millet-bermudagrass pasture or grain-fed for 90 days on a high-concentrate diet and were then commercially slaughtered. Warm carcass weights ranged from 167·8 kg to 324·3 kg. At 24 h post mortem, Texas Agricultural Experiment Station personnel (1) assigned scores or took measurements on each carcass for all factors used in yield grading and quality grading, (2) measured the length of hind leg (HL) and carcass length (CL) and (3) assigned a score for carcass muscling (MS) and, as appropriate, made an adjusted longissimus muscle area (ALA) evaluation. The 9th-10th-11th rib section from one side of each carcass was physically separated into longissimus muscle, fat, 'other soft tissue' and bone and ether extract determinations of the longissimus muscle and 'other soft tissue' components were made and used to adjust the yields of each of these components to a fat-free basis. Muscle to bone ratios ranged from 2·38 to 4·37. With both age and carcass weight held constant, diet, breed and sex explained only 35·8% of the variation in muscle to bone ratio. The best simple correlation with muscle to bone ratio was ALA/CL (r = ·59). Other measures significantly correlated with muscle to bone ratio included ALA (r = 0·55), MS (r = 0·50) and carcass weight (r = 0·49). Multiple regression analyses identified a three-variable subset comprised of ALA, carcass weight and CL which was related (P < 0·01) to muscle to bone ratio R(2) = 0·41). Data suggest that muscle to bone ratios differ widely among beef carcasses of similar genetic-management history and that there are carcass measures useful for predicting muscle to bone ratio.     

Characterization of loin shape from Duroc and Duroc composite finishing gilts

Gilts (n=45) were used in this study to characterize the effect of genotype on loin characteristics and quality over the length of the loin. Three diverse genotypes included a high quality Duroc line (A), a Duroc based composite line selected for lean growth (B), and an F1 cross of the two (C). After harvest, bone-in loins were removed from the carcass and cut perpendicular to the backbone at the 5th/6th rib, 7th/8th rib, 10th/11th rib, last rib, midlumbar, and the loin/sirloin juncture. Quality measurements were obtained at the 5th/6th rib, 10th/11th rib, and the loin/sirloin juncture. Digital images were taken of each surface (n=6) and analyzed for the determination of loin muscle area (LMA), muscle width, muscle depth (at three locations across the loin face), and fat depth. The average loin depth was calculated and used to calculate the loin depth:width ratio as an indication of loin shape or conformation. Loins from line A had the lowest (P<0.05) subjective color score, had the highest (P<0.05) amount of marbling, and were the firmest (P<0.05) of all three lines. There were also differences (P<0.05) between genetic lines for LMA, width, all three depths, fat depth, and depth:depth ratios. The most posterior portions of the loin had the largest (P<0.05) LMA, loin width, fat depth, and muscle depth 1. However, the more anterior portions of the loin had greater (P<0.01) values for the depth:width ratio and muscle depth:depth ratios.     

Beef carcasses with larger eye muscle areas, lower ossification scores and improved nutrition have a lower incidence of dark cutting

This study evaluated the effect of eye muscle area (EMA), ossification, carcass weight, marbling and rib fat depth on the incidence of dark cutting (pH(u)>5.7) using routinely collected Meat Standards Australia (MSA) data. Data was obtained from 204,072 carcasses at a Western Australian processor between 2002 and 2008. Binomial data of pH(u) compliance was analysed using a logit model in a Bayesian framework. Increasing eye muscle area from 40 to 80cm(2), increased pH(u) compliance by around 14% (P<0.001) in carcasses less than 350kg. As carcass weight increased from 150kg to 220kg, compliance increased by 13% (P<0.001) and younger cattle with lower ossification were also 7% more compliant (P<0.001). As rib fat depth increased from 0 to 20mm, pH(u) compliance increased by around 10% (P<0.001) yet marbling had no effect on dark cutting. Increasing musculature and growth combined with good nutrition will minimise dark cutting beef in Australia.     

Effects of genotype, level of supplementation, and organic chromium on growth performance, carcass, and meat traits grazing lambs

The aim of the present study was to evaluate the effects of Suffolk×Dorper (SD) and Rambouillet (R) lamb genotypes, dietary supplementation, and organic chromium on growth performance, carcass, and meat traits in male lambs grazing ryegrass pasture. SD lambs had heavier cold carcass (HCW) and better carcass yield (CY) and rib eye area at 12th rib (RA) than R lambs; R had larger legs. Feed supplement increased average daily weight gain (ADG), slaughter live weight (SLW), hot carcass weight (HCW) and cold carcass weight (CCW), carcass yield, carcass length (CL), leg perimeter (LP), major thorax width (MTW), minor thorax width (MiTW), rib eye area and dorsal fat at 12th rib (DF12), and also decreased meat moisture. Organic chromium reduced dorsal fat at 12th rib and meat fat content.     

The estimation of beef carcass muscle using cross-sectional area of M. longissimus dorsi at the fifth rib

The improvements in the accuracy of prediction of side muscle (weight and proportion) using measurements of eye muscle area at the 10th rib (EMA(10)) and eye muscle area at the 5th rib (EMA(5)), were compared in 48 steers, grain-fed for the Japanese market. For side muscle proportion the addition of EMA(10) to hot side weight and a fat thickness measurement did not improve prediction but the addition of EMA(5) did. P8 fat thickness together with hot side weight and EMA(5) (each, P<0·001) predicted side muscle proportion with an SEE of 2·05% and an R(2) of 61%, while the values for 10th rib thickness together with hot side weight and EMA(5) (each, P<0·001) were 2·09% and 68%, respectively. For the prediction of side muscle weight a fat thickness measurement and hot side weight (both, P<0·001) explained 77-84% of variance; the addition of an eye muscle area measurement further improved prediction with the most accurate being P8 fat thickness together with hot side weight and EMA(5).     

How many muscle samples are required to obtain reliable estimations of muscle fibre characteristics from pig longissimus muscle?

In order to investigate the reliability of muscle fibre trait estimations of pig longissimus muscle and to derive the minimum number of samples required per muscle cross-section and animal, intraclass correlation coefficients (ICC, ??) were obtained by one-way analysis of variance. From each of 23 market weight pigs five samples, evenly distributed over the muscle cross-sectional area at the 12th/13th rib level, were taken and analyzed for various muscle fibre traits. The number of samples required per muscle cross-section was found to be different between selected fibre traits, ranging from a minimum of three (for number of muscle fibres) to a maximum of five or more (for mean fibre area, fibre type composition and relative area occupied by each fibre type). These findings should be taken as a recommendation, but their usefulness will depend upon the goal and conditions of future experiments.     

The estimation of sheep carcass composition from fat and muscle thickness measurements taken by probes

Three trials, involving a total of 290 lambs, were carried out to examine the precision of probed fat and muscle measurements for estimating carcass composition in classification and grading schemes. The measurement positions and probes were not always the same in different trials but common measurements provided the basis for comparison between trials. Residual standard deviations (sd) for the prediction of carcass lean percentage averaged over trials are referred to in this Summary. Residual standard deviation for prediction from carcass weight was 3·5. The visual fat assessment currently used in the national Sheep Carcase Classification Scheme, operated by MLC, contributed significantly to the prediction (residual standard deviation = 3·0) but was less precise than a visual assessment of carcass subcutaneous fat content to the nearest percentage unit (SF(e)) (residual standard deviation = 2·6). Fat thickness measurements taken over the M. longissimus at the 12th rib with the Danish optical probe, a simple steel rule or the pig version of the Hennessy Grading Probe (HGP), showed similar precision to the classification fat class. An M. longissimus thickness measurement taken by the HGP did not add significantly to the precision. Probe fat measurements added significantly to the precision achieved with visual fat assessments (residual standard deviation with classification fat class = 2·8; residual standard deviation with SF(e) = 2·5). There would be advantages, therefore, in using both a visual fatness assessment and fat measurements in classification.     

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 value of in vivo real time ultrasonography in assessing loin muscularity and carcass composition of rabbits

Sixty nine growing rabbits were scanned over the lumbar region using a real time ultrasonography (RTU) machine to estimate loin muscularity and carcass composition. Longissimus thoracis et lumborum muscle (LM) depth, width and area were taken. Animals were weighed (LW), slaughtered and carcass composition was determined. Equivalent measurements to those taken by RTU in vivo were taken on the carcass and muscularity indices were calculated on carcass and in vivo. Simple correlations between the two types of measurements were determined and carcass composition was estimated by simple and multiple regressions. The LW varied from 1200 to 3410g. The simple correlations between carcass and in vivo RTU LM measurements were high (P<0.001) and the LM area was the trait with the highest correlation (r=0.92). Simple correlations between muscularity indices measured by RTU and in carcass were significant (P<0.001). In vivo RTU measurements explained a large amount of the variation of the carcass meat weight (MW) and bone weight (r(2) range from 0.49 to 0.77; P<0.001). Using multiple regression equations to estimate carcass composition, the best fit was obtained with the LW and one or more in vivo RTU measurement. The LW explained 90.6% of the variation of MW in the carcass. In vivo RTU is able to estimate loin muscularity and carcass composition of rabbits with accuracy. The usefulness of in vivo RTU and LW to predict carcass composition of rabbits using multiple regressions was also shown.     

CORRELATIONS BETWEEN SERUM CONCENTRATIONS OF LEPTIN AND BEEF CARCASS COMPOSITION AND QUALITY

Steers (n = 84) of various genotypes raised under diverse management conditions from the 2001 Missouri State Beef carcass contest were used to evaluate the relationship between serum concentrations of leptin and beef carcass composition and quality. Serum and carcass data including hot carcass weight; adjusted 12^th rib fat thickness; percentage kidney; pelvic and heart fat (KPH); marbling score; and USDA yield grades were measured at harvest. Leptin was correlated with back fat thickness over the 12^th rib, yield grade, and marbling score (r = 0.35, r = 0.19, r = 0.26 , P < 0.10; respectively), but not with hot carcass weight, ribeye area, or KPH (P > 0.10). Serum concentrations of leptin may be useful to objectively evaluate carcass composition in fed cattle and may provide a means by which carcass quality can be predicted in the live animal.