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

Abstract

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.

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

“…Previous studies using 336 steers (Conroy et al, 2009a) and 74 bulls (Conroy et al, 2009b) showed carcass conformation and fat scores to be potential predictors of carcass meat, fat and bone proportions. This study includes animals used by Conroy et al (2009a and2009b) in addition to bulls, heifers Table 4 Prediction equations for meat, fat and bone proportion estimated using a linear model on the entire data set (662 animals) using hindquarter weights. The table contains the intercept and regression coefficient of the regression model estimated from the entire data set including the R 2 of the model fit using the entire data set.…”

“…Following a period of 24 h at 48C, the right side of each carcass was quartered at the fifth rib into an eight-rib hindquarter (pistola) and the remaining forequarter. After recording the weight, the hindquarter was dissected into 13 cuts (leg, heel, silverside, topside, knuckle, rump, tail of rump, cap of rump, fillet, strip loin, cube roll, cap of rib and eye of the round) from which all visible fat and bone (where applicable) were removed (Conroy et al, 2009a). The weight of each individual meat cut and total fat from the hindquarter was recorded, as was bone weight following the removal of all adhering lean tissues.…”

“…Lean trim was weighed separately and included with the meat cuts to give total hindquarter meat yield. A similar procedure was carried out with the forequarter, which was dissected into 11 cuts (front shin, neck, brisket, chuck, flat ribs (1 to 5), plate, M. triceps brachii, bladesteak, braising muscle, chuck tender and clod; Conroy et al, 2009a). Hind-and forequarter meat, fat and bone weights were combined to give the weight of each component in the half carcass.…”

“…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). Muldowney et al (1997) reported that although conformation (EUROP coded 1 to 5) and fat scores (1 to 5) are routinely measured on beef -E-mail: mark.mcgee@teagasc.ie carcasses, their value as indicators of carcass characteristics and commercial value is not well established.…”

“…Muldowney et al (1997) reported that although conformation (EUROP coded 1 to 5) and fat scores (1 to 5) are routinely measured on beef -E-mail: mark.mcgee@teagasc.ie carcasses, their value as indicators of carcass characteristics and commercial value is not well established. Carcass conformation and fat scores have explained moderate to high proportions of the variation (R 2 ranged from 0.47 to 0.70) in carcass meat yield (Perry et al, 1993b;Drennan et al, 2008;Conroy et al, 2009a and2009b). According to Gardner et al (1997), the evaluation technique used to predict meat yield must be able to function online in a commercial setting without disrupting the normal product flow.…”