Effect of carcass price fluctuations on genetic and economic evaluation of carcass traits in Japanese Black cattle 1 T. Ibi,* 2 A. K. Kahi,† and H. Hirooka† *Department of Animal Research, Agura Farm, Nasushiobara, 325-0033, Japan and †Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan ABSTRACT: The objectives of this study were 1) to investigate the effect of changes in carcass market prices due to bovine spongiform encephalopathy (BSE) occurrences on estimates of genetic parameters and eco- nomic weights for carcass traits; and 2) to compare direct and indirect approaches for prediction of genetic merit of Japanese Black cattle for profitability of their progeny. The direct approach utilized estimated breed- ing values of carcass prices, whereas in the indirect approach, selection indices were constructed as prod- ucts of economic weights and breeding values of compo- nent traits. Data were composed of 80,191 carcass re- cords divided into 5 periods based on changes in carcass prices as a result of occurrences of BSE in Japan and the United States. The periods ranged from a period before occurrence of BSE in Japan to a period of beef import restrictions and a rise in prices. Carcass traits analyzed included HCW, LM area, rib thickness, subcu- taneous fat thickness, and marbling score (MS). Price traits included carcass unit price and carcass sale price. Estimates of heritability for price traits were moderate (0.32 to 0.46) and slightly sensitive to changes in carcass market prices. Genetic correlations of HCW and LM Key words: bovine spongiform encephalopathy, carcass price, economic weight, genetic parameter ©2006 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2006. 84:3204–3211 doi:10.2527/jas.2005-610 INTRODUCTION Carcass traits in beef cattle are important determi- nants of meat quality. In Japan, genetic parameters for carcass traits have been estimated for the Japanese beef cattle (i.e., Wagyu; Mukai et al., 1995; Hirooka and Matsumoto, 1996; Oikawa et al., 2000; Ibi et al., 2005). Traditionally, selection index or multiple trait BLUP methods have been applied to estimate breeding values 1 These field data were collected by staff of the Agura Farm. Their help is gratefully acknowledged. 2 Corresponding author: ibi-agr@rmail.plala.or.jp Received October 21, 2005. Accepted June 1, 2006. 3204 area with price traits increased and that between MS and carcass sale price decreased with period, whereas estimates of genetic correlation between MS and car- cass unit price were high in all periods (0.96 to 0.98). Economic weights for carcass traits varied with periods because carcass prices were highly sensitive to eco- nomic importance of traits. Nevertheless, correlations between within-period breeding values for price traits estimated using direct and indirect approaches were high (0.92 to 0.99). This result indicates that selection realized by direct and indirect approaches will provide very similar results. A comparison among within-ap- proach breeding values estimated in different periods showed that the largest differences in breeding values of sires for price traits were between the periods after occurrences of BSE in Japan and in the United States. Economic effects of BSE occurrences influenced the im- portance of carcass traits and economic merits of price traits through a change of carcass prices from period to period, irrespective of the approach taken in de- termining the genetic merit of breeding animals for profitability of their progeny. of multiple traits and to predict the aggregate geno- types. Economic weights are used to combine the esti- mated breeding values for the component traits into an estimated breeding value for aggregate genotype for selection purposes. This approach (so-called indirect ap- proach), although very useful, assumes that genetic pa- rameters for all traits are known and may be affected by nonlinear relationships between traits. Visscher and Goddard (1995) and Pe ´rez-Cabal and Alenda (2003) proposed an alternative approach (so- called direct approach) that deals with prediction of profit breeding value considering profit as a trait for evaluation, when information on profit is available on individual animals. The direct approach requires few genetic parameters and implicitly considers nonlinear relationships between traits. However, profit of animals Published December 8, 2014