2009 State Fair of Virginia Lamb Carcass Evaluation Summary
Since 1999, more than 2020 lambs have been evaluated through the Lamb Carcass Contest held in conjunction with the youth market lamb show at the State Fair of Virginia. The program serves as an educational tool for exhibitors and breeders regarding factors that influence the production of lean lamb that fits industry and consumer targets.
Five premium categories (Gold, Purple, Blue, Red, and Pink) have been established to rank lambs based on their combination of carcass merit and growth performance. The following standards were utilized, with carcasses failing to meet one or more of these qualifications placed in the Pink group:
Minimum fat thickness of 0.10 in.
Maximum fat thickness of 0.35 in. (maximum Yield Grade of 3.9)
Minimum LMA for carcass weight using formula: 1.4 + (0.02 x HCW)
Minimum Quality Grade of Choice
Minimum carcass weight of 45.0 pounds
Carcasses meeting all of the above standards were ranked using carcass merit (determined by percentage boneless, closely trimmed retail cuts- %BCTRC) and live average daily gain (ADG). The formula to estimate %BCTRC utilizes carcass weight, fat thickness, body wall thickness, and loin muscle area and represents the predicted proportion of the carcass that is saleable retail product. Average daily gain is calculated for each lamb from the time of nomination in late June to the State Fair in early October (approximately 100 days). The average ADG of all lambs exhibited in the live show serves as the benchmark ADG value within year. Carcass premium categories were established as follows:
| Premium Category | Carcass and ADG Parameters |
| Gold | > 50.0 %BCTRC & > 0.45 ADG |
| Purple | > 50.0 %BCTRC & ADG < 0.45 or > 49.0 %BCTRC & > average ADG |
| Blue | > 49.0 %BCTRC & ADG < average or > 47.5 %BCTRC & > average ADG |
| Red | > 47.5 %BCTRC & ADG < average or %BCTRC < 47.5 |
| Pink | Carcasses failing to meet one or more of the standards |
The following table summarizes the carcass information since beginning the program. Compared to the first five years of the program (1999-2003), live weights and corresponding carcass weights of lambs have gotten heavier. Associated with this weight increase has been an increase in ADG, loin muscle area (LMA), and fatness. While a portion of the increase in LMA is directly related to weight, the lambs have also improved in overall muscling, as indicated by a higher percentage of the lambs meeting the minimum LMA standard for their carcass weight. Despite the increases in weight over time, fat thickness and overall cutability (%BCTRC) have remained relatively constant. A very high percentage of the carcasses are YG 1 and 2, and the low percentage of undesirable YG 4 carcasses is much more favorable than industry average.
The 2009 lambs were very similar to those from the previous five years (2004-2008). However, the 2009 lambs tended to be slightly fatter and there were more lambs which were overfed as indicated by the increased percentage of Yield Grade 4 lambs as well as more lambs failing to meet the minimum LMA standard.
see attached State Fair of Virginia Lamb Carcass Contest Summary
Rights
Virginia Cooperative Extension materials are available for public use, re-print, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.
Publisher
Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Rick D. Rudd, Interim Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Wondi Mersie, Interim Administrator, 1890 Extension Program, Virginia State, Petersburg.
Date
November 6, 2009