Prediction of retail product weight and percentage using ultrasound and carcass measurements in beef cattle

Abstract

Data from 534 steers representing six sire breed groups were used to develop live animal ultrasound prediction equations for weight and percentage of retail product. Steers were ultrasonically measured for 12th-rib fat thickness (UFAT), rump fat thickness (URPFAT), longissimus muscle area (ULMA), and body wall thickness (UBDWALL) within 5 d before slaughter. Carcass measurements included in USDA yield grade (YG) and quality grade calculations were obtained. Carcasses were fabricated into boneless, totally trimmed retail products. Regression equations to predict weight and percentage of retail product were developed using either live animal or carcass traits as independent variables. Most of the variation in weight of retail product was accounted for by live weight (FWT) and carcass weight with R2 values of 0.66 and 0.69, respectively. Fat measurements accounted for the largest portion of the variation in percentage of retail product when used as single predictors (R2 = 0.54, 0.44, 0.23, and 0.54 for UFAT, URPFAT, UBDWALL, and carcass fat, respectively). Final models (P < 0.10) using live animal variables included FWT, UFAT, ULMA, and URPFAT for retail product weight (R2 = 0.84) and UFAT, URPFAT, ULMA, UBDWALL, and FWT for retail product percentage (R2 = 0.61). Comparatively, equations using YG variables resulted in R2 values of 0.86 and 0.65 for weight and percentage of retail product, respectively. Results indicate that live animal equations using ultrasound measurements are similar in accuracy to carcass measurements for predicting beef carcass composition, and alternative ultrasound measurements of rump fat and body wall thickness enhance the predictive capability of live animal-based equations for retail yield.

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

“…Similarly, Bjelka et al (2002) reported that the lowest content of separable fat in bulls was in conformation class E and it gradually increased through to the poorer classes. The significant negative correlation of carcass fat score with carcass meat proportion is similar to previous findings (May et al, 2000;Greiner et al, 2003). In accordance with Drennan et al (2008), significant positive correlations were obtained between carcass fat score with carcass fat proportion and perinephric and retroperitoneal fat.…”

“…The positive correlation (r 5 0.52) between pre-slaughter scanned muscle depth and carcass meat proportion is within the range (0.30 to 0.84) found in some studies (Doorley, 2001;Tait et al, 2005), but higher than other (r 5 0.07 to 0.17) results (Hamlin et al, 1995;May et al, 2000;Greiner et al, 2003). The generally non-significant relationship between scanned muscle depth and the three indicators of carcass fat was as expected, and the high negative relationship with carcass bone proportion (r 5 20.75) was in agreement with Bailey et al (1986).…”

“…Previous studies (Perry et al, 1993a;MacAodhá in, 2004;Drennan et al, 2008) have shown that live animal muscular scores were useful in predicting meat yield. Furthermore, Greiner et al (2003) found that live animal ultrasound measurements of the longissimus dorsi were useful predictors of retail product. Live animal ultrasound measurements were shown to have a good relationship with carcass meat proportion (Faulkner et al, 1990;Tait et al, 2005).…”

High-energy forage feeding diets and body condition on the finishing of cull dairy cows

“…However, higher correlation coefficients between carcass and ultrasound measurement of the 12th rib (SBT and SF 12 ) were shown by Bullock et al (1991; Tables 3 and 4), in accordance with the results from Greiner et al (2003) study. Some studies reported an average absolute low difference between ultrasound and carcass measurement in the 12th rib fat (SBT and SF 12 ) for steers, such as 0.16 cm (Greiner et al, 2003) and 0.19 cm (Brethour, 1992). However, our results showed averaged differences of 0.5 cm for cull dairy cows, likely because the magnitude of the differences between SF 12 and SBT increases as SF 12 increases (Brethour, 1992;Greiner et al, 2003).…”

“…Some studies reported an average absolute low difference between ultrasound and carcass measurement in the 12th rib fat (SBT and SF 12 ) for steers, such as 0.16 cm (Greiner et al, 2003) and 0.19 cm (Brethour, 1992). However, our results showed averaged differences of 0.5 cm for cull dairy cows, likely because the magnitude of the differences between SF 12 and SBT increases as SF 12 increases (Brethour, 1992;Greiner et al, 2003). SF 12 and SBT determined the subcutaneous fat thickness on the 12th rib by different methods.…”