Comparison of live and carcass equations predicting percentage of cutability, retail product weight, and trimmable fat in beef cattle3

This study examined the relationship of muscular and skeletal scores and ultrasound measurements in the live animal, and carcass conformation and fat scores with carcass composition and value using 336 steers, slaughtered at 2 years of age. Live animal scores and measurements were recorded at 8 to 12 months of age and pre-slaughter. Following slaughter, each carcass was classified for conformation and fatness and the right side dissected into meat, fat and bone. Carcass conformation scores and fat scores were both measured on a continuous 15-point scale and ranged from 2.0 to 12.0 and from 2.8 to 13.3, respectively. Pre-slaughter muscular scores showed positive correlations ( P , 0.001) ranging from 0.31 to 0.86 with carcass meat proportion, proportion of high-value cuts in the carcass, conformation score and carcass value, significant negative correlations with carcass fat (r 5 20.13) and bone (r 5 20.81) proportions, and generally low non-significant relationships with the proportion of high-value cuts in meat and carcass fat score. Pre-slaughter ultrasound muscle depth and carcass conformation score showed similar correlations with carcass traits to those using the pre-slaughter muscular scoring procedure. Pre-slaughter ultrasound fat depth showed positive correlations ( P , 0.001) with carcass fat proportion (r 5 0.59) and fat score (r 5 0.63), and significant negative correlations (20.23 to 20.50) with carcass meat and bone proportions, high-value cuts in the carcass and in meat, and carcass value. Pre-slaughter skeletal scores generally showed poor correlations ranging from 20.38 to 0.52 with the various carcass traits. Corresponding correlations (20.26 to 0.44) involving records collected at 8 to 12 months of age were lower than those using pre-slaughter records. A one-unit increase in carcass conformation score increased carcass meat proportion and value by 11.2 g/kg and 5.6 cents/kg, respectively. Corresponding values for fat score were 28.2 g/kg and 25.1 cents/kg. In conclusion, both pre-slaughter live animal scores/measurements and carcass classification scores, explained an appreciable amount of the total variation in carcass meat, fat and bone proportions and carcass value, and a moderate amount of the variation in proportion of high-value meat cuts in the carcass.

Section: Assessorscontrasting

confidence: 80%

Section: Assessorsmentioning

confidence: 90%

Section: Assessorsmentioning

confidence: 99%

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The relationship of live animal muscular and skeletal scores, ultrasound measurements and carcass classification scores with carcass composition and value in steers

Conroy

Drennan

Kenny

et al. 2009

“…Machine classification is deemed preferable to visual assessment because of greater consistency, and producers can have more confidence in the objectivity of the results (Allen, 2007). Several studies quantified the associations of ultrasound (Faulkner et al, 1990;Herring et al, 1994;Hamlin et al, 1995) and live animal scores (Perry et al, 1993a and1993b) with carcass traits. However, few studies have examined the relationship between EU carcass classification scores and carcass composition (Drennan et al, 2008;Conroy et al, 2009a and2009b).…”

Section: Introductionmentioning

confidence: 99%

Predicting beef carcass meat, fat and bone proportions from carcass conformation and fat scores or hindquarter dissection

Conroy

Drennan

McGee

et al. 2010

Equations for predicting the meat, fat and bone proportions in beef carcasses using the European Union carcass classification scores for conformation and fatness, and hindquarter composition were developed and their accuracy was tested using data from 662 cattle. The animals included bulls, steers and heifers, and comprised of Holstein-Friesian, early-and late-maturing breeds 3 HolsteinFriesian, early-maturing 3 early-maturing, late-maturing 3 early-maturing and genotypes with 0.75 or greater late-maturing ancestry. Bulls, heifers and steers were slaughtered at 15, 20 and 24 months of age, respectively. The diet offered before slaughter includes grass silage only, grass or maize silage plus supplementary concentrates, or concentrates offered ad libitum plus 1 kg of roughage dry matter per head daily. Following the slaughter, carcasses were classified mechanically for conformation and fatness (scale 1 to 15), and the right side of each carcass was dissected into meat, fat and bone. Carcass conformation score ranged from 4.7 to 14.4, 5.4 to 10.9 and 2.0 to 12.0 for bulls, heifers and steers, respectively; the corresponding ranges for fat score were 2.7 to 11.5, 3.2 to 11.3 and 2.8 to 13.3. Prediction equations for carcass meat, fat and bone proportions were developed using multiple regression, with carcass conformation and fat score both included as continuous independent variables. In a separate series of analyses, the independent variable in the model was the proportion of the trait under investigation (meat, fat or bone) in the hindquarter. In both analyses, interactions between the independent variables and gender were tested. The predictive ability of the developed equations was assed using cross-validation on all 662 animals. Carcass classification scores accounted for 0.73, 0.67 and 0.71 of the total variation in carcass meat, fat and bone proportions, respectively, across all 662 animals. The corresponding values using hindquarter meat, fat and bone in the model were 0.93, 0.87 and 0.89, respectively. The bias of the prediction equations when applied across all animals was not different from zero, but bias did exist among some of the genotypes of animals present. In conclusion, carcass classification scores and hindquarter composition are accurate and efficient predictors of carcass meat, fat and bone proportions.

“…Accurate prediction of carcass value or quality based on body composition would enable early selection of efficient animals by beef producers as well as seed-stock breeders. A subset of the data from this study was used to describe the effectiveness of objective live measurements equations for the prediction of carcass traits (Afolayan et al, 2002a), as opposed to the combination of objective and subjective measurements used in other studies (Perry et al, 1993a and b;Herring et al, 1994). Objective live animal measurements involved simple adoptable techniques that would reduce production costs and allow wider application by the producers.…”

Section: Introductionmentioning

confidence: 99%

Breed variation and genetic parameters for growth and body development in diverse beef cattle genotypes

Afolayan

Pitchford

Deland

et al. 2007

Conformation scores can account for more than 20% of cattle price variation at Australian livestock sales. However, there are limited available references which define genetic factors relating objective live developmental traits to carcass composition. Weaning and post-weaning weight, height, length, girth, muscle (ratio of stifle to hip width) and fat depth of 1202 progeny from mature Hereford cows (637) mated to seven sire breeds (Jersey, Wagyu, Angus, Hereford, South Devon, Limousin and Belgian Blue) were examined for growth and development across ages. Crossbred Wagyu and Jersey were both lighter in weight and smaller in size (height, length and girth) than purebred Hereford and crossbred Angus, South Devon, Limousin and Belgian Blue. Within the five larger crossbreds, there were significant changes in relative weight from weaning to 600 days. Sire breeds differed in fat depth, with Angus being the fattest (9% on average fatter than Hereford and Wagyu), and Jersey 5% less fat than Hereford, followed by South Devon and Limousin (19% lower than Hereford) and Belgian Blue (39% lower than Hereford). Direct heritability ranged from 19 to 42% and was higher than the proportion of total phenotypic variance accounted for by maternal effects (which ranged from 0 to 17%) for most body measurement traits except for weight (38 v. 18%) and girth (36 v. 9%) traits at weaning, an indication of maternal effect on some body conformation traits at early ages. Muscularity (19 to 44%) and fat depth (26 to 43%) were moderately to highly heritable across ages. There were large differences for growth and the objective measures of body development between crossbreds with a degree of overlap among the progeny of the seven sire breeds. The variation between genetic (positive) and environmental (negative) correlations for dry versus wet season average daily gains in weight and fat, suggested the potential use of live-animal conformation traits for within breed selection of genetically superior animal in these traits across seasons.