National Beef Quality Audit-2011: Survey of instrument grading assessments of beef carcass characteristics.

The instrument grading assessments for the 2011 National Beef Quality Audit evaluated seasonal trends of beef carcass quality and yield attributes over the course of the year. One week of instrument grading data, HCW, gender, USDA quality grade (QG), and yield grade (YG) factors, were collected every other month (n = 2,427,074 carcasses) over a 13-mo period (November 2010 through November 2011) from 4 beef processing corporations, encompassing 17 federally inspected beef processing facilities, to create a "snapshot" of carcass quality and yield attributes and trends from carcasses representing approximately 8.5% of the U.S. fed steer and heifer population. Mean yield traits were YG (2.86), HCW (371.3 kg), fat thickness (1.19 cm.), and LM area (88.39 cm(2)). The YG distribution was YG 1, 15.7%; YG 2, 41.0%; YG 3, 33.8%; YG 4, 8.5%; and YG 5, 0.9%. Distribution of HCW was <272.2 kg, 1.6%; 272.2 to 453.6 kg, 95.1%; and ≥453.6 kg, 3.3%. Monthly HCW means were November 2010, 381.3 kg; January 2011, 375.9 kg; March 2011, 366.2 kg; May 2011, 357.9 kg; July 2011, 372.54 kg; September 2011, 376.1 kg; and November 2011, 373.5 kg. The mean fat thickness for each month was November 2010, 1.30 cm; January 2011, 1.22 cm; March 2011, 1.17 cm; May 2011, 1.12 cm; July 2011, 1.19 cm; September 2011, 1.22 cm; and November 2011, 1.22 cm. The overall average marbling score was Small(49). The USDA QG distribution was Prime, 2.7%; Top Choice, 22.9%; Commodity Choice, 38.6%; and Select, 31.5%. Interestingly, from November to May, seasonal decreases (P < 0.001) in HCW and fat thicknesses were accompanied by increases (P < 0.001) in marbling. These data present the opportunity to further investigate the entire array of factors that determine the value of beef. Data sets using the online collection of electronic data will likely be more commonly used when evaluating the U.S. fed steer and heifer population in future studies.