Abstract

GUITOU, Horacio R; MONTI, Aldo; SUTZ, Guillermo  and  BALUK, Inés. Interpretation and use of Expected Progeny Differences (EPD) as a selection tool for beef quality: Part two. Rev Colom Cienc Pecua [online]. 2007, vol.20, n.3, pp.363-376. ISSN 0120-0690.

With the purpose to improve the traits of economic interest related not only to the reproductive efficiency and the potential of growth but to beef quality, the Argentine Angus Association carries out programs of objective evaluation of Angus seedstock animals through an agreement signed with INTA, offering genetic information (Expected Progeny Differences, EPD) on them. At the moment, EPDs is the best tool to produce agreed directional changes to the demand of the different internal and external markets in the mentioned traits. From year 2002, the Angus Sire Summaries provide Ultrasound EPD for rib eye area (REA), percentage of intramuscular fat (%IMF), back fat thickness (BFAT), rump fat thickness (RFAT) and percentage of retail product (%RP). In order to obtain this, in the first place, this Association elaborated and approved the “Protocol for Ultrasound Beef Quality Data Collection”, according to the guidelines established by Iowa State University, USA. Then, in 2004, this Association created the “Ultrasound Images Interpretation Center” (CIIE). In this way, the ultrasound images taken by certified technicians are interpreted in a fair way in the CIIE by specialists certified in USA. Thus, from the resulting information, as much from these ultrasound measurements as of the reproduction and growth traits, plus the pedigree database of the breed, the corresponding EPD are obtained. EPDs were based on the methodology of Mixed Models with BLUP statistical properties (Best Linear Unbiased Prediction). For beef quality traits it was used the Multiple Traits Animal Model. In this way, in the “Angus Sire Summary 2005”, from a total of 11000 animals measured by ultrasound, 771 Bulls were evaluated for beef quality traits. The average of ultrasound measures adjusted to 550 days obtained for pedigree males and females were, respectively: 1) BFAT, 6.1 (n = 3558) and 6.0 mm (n = 1532); 2) RFAT, 7.9 (n = 3364) and 7.6 mm (n = 1448); 3) REA, 84.4 (n = 3734) and 72.5 cm2 (n = 1638); and 4) % IMF, 2.6 (n = 3450) and 3.1% (n = 1514). The average of ultrasound measures for purebred males and females were, respectively: 1) BFAT, 3.8 (n = 2477) and 3.2 mm (n = 955); 2) RFAT, 4.8 (n = 2337) and 4.1 mm (n = 856); 3) REA, 72.1 (n = 2824) and 54.9 cm2 (n = 917); and 4) %IMF, 2.2 (n = 1802) and 2.8% (n = 578). Data from pasture-base systems in Argentine showed similar values to those found in pasture-based Australian systems.

Keywords : angus; bovine; EPD; genetics; genetic improvement; heifer; yearling bulls.

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