Comparing the Canadian pork lean yields and grading indexes predicted from grading methods based on Destron and Hennessy probe measurements

Pomar, C. and Marcoux, M. 2003. Comparing the Canadian pork lean yields and grading indexes predicted from grading methods based on Destron and Hennessy probe measurements. Can. J. Anim. Sci. 83: 451-458. In Canada, actual grading methods based on Destron (DPG) and Hennessy (HGP) probe measurements were approved in 1994. This study was undertaken to verify if both grading methods predict similar lean yields and grading indexes in actual pork carcasses. Data from the following four databases were used, and included hot carcass weight, and backfat and muscle depths as measured by both probes: 1281 carcasses from the 1992 National Cutout, 495 and 76 carcasses from 1997 and 1998 Federation des Producteurs de Pore du Quebec studies respectively, and 266 from a 1999 Agriculture and Agri-Food Canada study. Probes were inserted alternatively at the Canadian grading site. Grading indexes were assigned from a 1999 official grid. For the four studied databases, the HGP-DPG lean yields were different from zero (P < 0.0001) with values of 0.33,0.35, 0.36 and 0.18%, chronologically. The HGP-DPG grading indexes were also different from zero with values of 0.51 (P < 0.0001), 0.36 (P < 0.0001) and 0.50 (P < 0.0001), 0.21 (P < 0.09), respectively. The slope between lean yields and indexes were different from one, indicating that the underestimation of lean yields and indexes by the DPG method increased with carcass leanness.