estimated to be 1.8in2 (12.3in2 x 15%). This difference, which is unpredictable without DNA testing, is nearly four times the possible change value for a 0% BIF accuracy, reported to be 0.46in2 for the rib eye EPD. When one parent is heterozygous for the mutation, and the other homozygous for the mutation or the normal form of the myostatin gene, the expected average difference in rib eye area of progeny will be about 0.9in2 (12.3in2 x 7.5%), depending on whether the mutation or normal form of the gene is inherited from the heterozygous parent. In this case, the unpredictable variation in rib eye area represents about twice the possible change value for a 0% BIF accuracy. Standard errors of prediction, also known as accuracy or possible change value in the context of EBV and EPD predictions, are dependent on the quality of information used to predict an animal's EBV or EPD for a given trait. Errors in estimating genetic merit are being addressed in research programmes that aim to supplement phenotypic data extensively used in current BLUP predictions with genotypic data. Comparisons with other breeds A USMARC long-term multi-breed study of Limousins, three British (Red Poll, Hereford, Aberdeen Angus) and five other continental European (Braunvieh, Pinzgauer, Gelbvieh, Simmental, Charolais) cattle breeds reported that Limousin cattle were the most efficient and fastest of all breeds at converting feed into saleable meat even though Limousin's live weight growth was the slowest. This arose because saleable meat yield expressed as percentage of live weight was significantly higher in Limousins than in most other cattle breeds. Saleable meat yield was an average 34.9% of live weight for the three British cattle breeds, compared with 40.4% for the five other continental European breeds, and 46.0% for Limousins, for two market end points of 225 kg saleable meat at 8mm fat trim, and 210 kg saleable meat at 0mm fat trim. Live weight gain for the Limousins averaged 1.27 kg/day, compared with an average 1.29 kg/day for the British breeds and 1.38 kg/day for the other continental European cattle. Limousin saleable meat gain averaged 585g/day, with the balance being 687g/day of low value or waste product, such as bone, trimmed fat, internal organs, and hide. The British breeds produced significantly less saleable meat (average 451g/day) and significantly more low value product (841g/day), while consuming about twice the feed of the Limousins from entry to the trial