The objective of the study was to analyze the Certified Angus Beef (CAB) program carcass database for trends associated with marbling score, fat cover, and CAB acceptance rate in Angus-type cattle. The CAB program carcass database is made up of over 100,000 records collected during 1989 to 1999. Steers make up 90 % of the database, and 89 % of the cattle were finished in the Midwest (NE, CO, KS). The majority of the cattle (62 %) were finished in Nebraska feedyards. The CAB program overall acceptance rate was 23.4 %. Marbling score (84.0 %) is the first limiting factor for CAB acceptance of steers. For steers, a combination of marbling score and yield grade (8.3 %) and yield grade alone (6.1 %) for steers are the second and third limiting factors for CAB acceptance, respectively. The phenotypic correlation between fat cover and marbling score is nearly zero for CAB steers, yet for non-CAB steers the correlation is 0.38 (p < .01). On the average, as yield grade increases from 2.0 to 4.0, by each tenth of a unit, marbling score increases by 0.3 % for every 1 % increase in fat cover for all steers. Comparing CAB steers versus non-CAB steers, marbling score increases by 0.05 % and 0.34 % for every 1 % increase in fat cover, respectively. As fat cover groups increase by 0.1 of an inch, CAB acceptance rate increases up to the 0.6- 0.69 inch group, then starts to decrease for steers. When looking at marbling score by fat cover groups, CAB steers increase 1.0 % for each 0.1 inch increase in fat cover, and for non-CAB steers, there is an increase of 5.0 %. Fat cover increases by 5.6 % and 14.2 % as you go from a USDA marbling score of small to modest and slight to modest, respectively, for all steers. Looking at the slaughter months, there is an increase in marbling score from April to August, although fat cover remains steady. Yet CAB acceptance rate decreases from April to June and then increases from June to November. Producers may be able to improve the CAB acceptance rate of their cattle if there is a clearer understanding of the relationship between traits that are included in the CAB specifications.
Iowa State University
Scott, Mark F.; Wilson, Doyle E.; and Rouse, Gene H., "Trends Associated with Marbling Score, Fat Cover, and CAB (Certified Angus BeefTM) Acceptance Rate" (2002). Beef Research Report, 2001. 24.