The prediction of retail beef yield from real time ultrasound measurements on live animals at three stages through growout and finishing

Abstract

Abstract. Analyses were performed to test the relationship between retail beef yield percentage (RBY) and real time ultrasound measurements taken at weaning, entry to finishing and preslaughter for animals finished under pasture and feedlot conditions to meet domestic, Korean and Japanese market specifications.The first analysis tested the power of live animal measurements (scanned P8 fat depth, scanned eye muscle area and liveweight) to predict RBY and contrasted this with a model containing these live animal measurements plus a term (HERD × KILL) which accounted for all known classification variables. This indicated that scanned P8 fat depth, measured at slaughter, was the most useful predictor of retail beef yield, accounting for 52% of the variation in RBY for the equation containing live animal measurements alone. The power of live animal measurements to predict RBY decreased as the time between scanning and slaughter increased. Models which included HERD × KILL predicted RBY accurately (accounting for 82-86% of the variation in RBY), but live animal measurements contributed little to this result, accounting for only 8% of the variation in RBY for measurements at slaughter in the presence of the HERD × KILL term.A second analysis examined whether market category, finishing regime or breed classifications consistently influenced the relationship between the measured traits and RBY at the 3 scanning times. The magnitude of the variation between significantly different coefficients (for scanned P8 fat depth, scanned eye muscle area and liveweight) was generally small, though the results suggested that in some instances, developing separate equations for animals of different classifications would marginally improve the accuracy of RBY prediction.The final analysis investigated the improvement in RBY prediction when measurements from entry to finishing were included with those taken before slaughter. HERD × KILL was included in the model to account for all known classification variables. Measurements of both P8 fat depth and EMA from the earlier measurement time were significant predictors of RBY in the presence of the corresponding measurement at slaughter, but accounted for an increase in R 2 of only 0.0007. It was concluded that a single scan and liveweight measurement, close to slaughter, would provide the best live animal measurements for RBY prediction, and that no improvement in accuracy would be achieved by additional scans taken earlier in an animal's life. IntroductionReal time ultrasound scanning (RTUS) has become an established technique for measuring carcass traits in live beef cattle. The accuracy and repeatability of measurements obtained using modern scanning equipment has been extensively tested and documented. Wilson et al. (1995) reviewed reports of recent scanning accuracies and found consistently high correlations between RTUS fat depth and eye muscle area (EMA) and the corresponding carcass measurements (r = 0.75-0.96 for fat depth and 0.60-0.94 for eye muscle area).The relationship between...

Prediction of retail beef yield and fat content from live animal and carcass measurements in Nellore cattle1

“…Slightly higher correlations (0.17 to 0.33) between LMA (measured by ultrasound or directly on the carcass) and percentage of retail beef were reported in the studies of Greiner et al (2003) and Tait et al (2005). Wolcott et al (2001) found significant differences in the relationship between live animal measurements (live weight, ULMA, and USRPFAT) and retail beef percentage when estimated within market beef category, finishing regimen, and breed, a potential difference in the results between studies.…”

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

“…This is in agreement with Bailey et al (1986) who obtained correlations of −0.16, 0.57 and 0.48 between scanned muscle area and carcass conformation score in light, medium and heavy weight categories, respectively, of Holstein bulls. Similarly, Wolcott et al (2001) found that the power of live animal measurements to predict retail meat yield percentage decreased as the time between scanning and slaughter increased.…”

Prediction of ossification from live and carcass traits in young beef cattle: model development and evaluation1

“…The USRIB and USEMA (M. longissimus thoracis et lumborum) measurements were taken at the 12th and 13th ribs (Barwick et al, 2009), the USP8 measurement was taken at the intersection between a line parallel to the spine from the tuber ischium and a line perpendicular to it from the spinous process of the third sacral vertebra (Johnston et al, 2003;Wolcott et al, 2009). All ultrasound measurements were taken by an accredited technician (Upton et al, 1999) with an Aloka 500V realtime ultrasound scanner using a 17-cm transducer (Corometrics Medical Systems Inc., Wallingford, CT), with vegetable oil as the coupling agent, and the fat depths were recorded using callipers built into the scanner (Wolcott et al, 2001).…”