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Title: PREDICTING CARCASS RETAIL PRODUCT IN BEEF STEERS AT VARIABLE FAT THICKNESS ENDPOINTS

Author
item GREINER, SCOTT - IOWA STATE UNIVERSITY
item ROUSE, GENE - IOWA STATE UNIVERSITY
item WILSON, DOYLE - IOWA STATE UNIVERSITY
item Cundiff, Larry
item Wheeler, Tommy

Submitted to: Beef Research Report
Publication Type: Other
Publication Acceptance Date: 5/15/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Two hundred eighty-two crossbred steers were scanned with real-time ultra- sound (RTU), slaughtered, and fabricated into retail cuts to determine the potential for a combination of live animal and ultrasound measures to predict carcass retail yield. Ultrasound measures of fat thickness, ribeye area, rump fat thickness, and body wall thickness, as well as live weight and visual muscle score were recorded three to five days prior to slaughte slaughter. Carcass measurements were taken, and one side of each carcass was fabricated into retail cuts with .3 inches of fat. Stepwise regression visual muscle score were recorded three to five days prior to slaughter. C analysis was used to compare possible models for prediction of percent retail product from carcass measurements or a combination of live animal traits and ultrasound measures. Results indicate that possible prediction models for percent retail product using live animal and RTU measures were similar in their predictive power and accuracy when compared with models derived from carcass measurements across all fat thickness ranges. A larger proportion of the variation in percent retail product can be explained in steers with less than .4 inches fat cover (using either RTU and live animal measures or carcass meaasures) when compared with steers with greater than .4 inches fat thickness.

Technical Abstract: Real time ultrasound (RTU) measures of carcass and meat characteristics on live beef cattle has potential to increase effectiveness of marketing to meet certain carcass specifications and to improve effectiveness of selection for carcass and meat traits in the seedstock herds. The objective of this study was to determine the efficiency of using RTU and other live animal measures to predict retail product in the carcass of steers that have similar fat thickness end points. Ultrasound measures of fat thickness, ribeye area, rump fat thickness, and body wall thickness as well as live weight and visual muscle score were recorded on 282 cross- bred steers produced in the Germplasm Evaluation Program at the U.S. Meat Animal Research Center. Carcass measures were taken, and one side of each carcass was fabricated into boneless-closely trimmed (8 mm) retail product (steaks, roasts, and ground beef with 20% fat). Possible prediction models sderived from RTU and other live animal measures were compared to models derived using traditional carcass measurements used to determine yield grade (carcass weight, fat thickness, estimated percentage kidney fat, and rib eye area). Results indicated that a combination of realtime ultrasound and other live animal measures are useful in predicting beef carcass per- centage retail product. The possible prediction models derived from RTU live animal measures are similar in their predictive power to those derived from carcass measures.