Characterization of biological types of cattle (Cycle V): Carcass traits and longissimus palatability 1,2 T. L. Wheeler 3 , L. V. Cundiff, S. D. Shackelford, and M. Koohmaraie Roman L. Hruska U.S. Meat Animal Research Center, ARS, USDA, Clay Center, NE 68933-0166 ABSTRACT: Carcass (n = 854) and longissimus thor- acis palatability (n = 802) traits from F 1 steers obtained from mating Hereford, Angus, and MARC III cows to Hereford or Angus (HA), Tuli (Tu), Boran (Bo), Brah- man (Br), Piedmontese (Pm), or Belgian Blue (BB) sires were compared. Data were adjusted to constant age (444 d), carcass weight (333 kg), fat thickness (1.0 cm), fat trim percentage (21%), and marbling (Small 00 ) end points. Results presented in this abstract are for age- constant data. Carcasses from BB- and HA-sired steers were heaviest (P < 0.05) and carcasses from Bo- and Tu-sired steers were lightest (P < 0.05). Adjusted fat thickness was greatest (P < 0.05) on carcasses from HA- sired steers and least (P < 0.05) on carcasses from BB- and Pm-sired steers. Numerical USDA yield grades were lowest (P < 0.05) for carcasses from Pm- and BB- sired steers and highest (P < 0.05) for carcasses from HA- and Br-sired steers. Marbling scores were highest (P < 0.05) for carcasses from HA- and Tu-sired steers and lowest (P < 0.05) for carcasses from Br-, BB-, and Key Words: Beef, Breeds, Carcass Composition, Meat Quality, Palatability, Tenderness 2001 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2001. 79:1209–1222 Introduction The first four cycles of the Germplasm Evaluation (GPE) program at the Roman L. Hruska U.S. Meat Animal Research Center (MARC) characterized 22 breeds representing several biological types of cattle. Carcass and longissimus palatability traits from these 1 Names are necessary to report factually on available data; how- ever, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable. 2 The authors wish to acknowledge the technical assistance of G. Hays, W. Smith, D. Powell, P. Beska, D. Kohmetscher, D. Light, J. Waechter, K. Theer, K. Mihm, and P. Tammen and the secretarial assistance of M. Bierman. 3 Correspondence: P.O. Box 166 (phone: 402-762-4229; fax: 402- 762-4149; E-mail: wheeler@email.marc.usda.gov). Received August 24, 2000. Accepted January 29, 2001. 1209 Pm-sired steers. Longissimus thoracis from carcasses of HA-, Pm-, and Tu-sired steers had the lowest (P < 0.05) 14-d postmortem Warner-Bratzler shear force values. Carcasses from HA-sired steers had longissi- mus thoracis with the highest (P < 0.05) tenderness ratings at 7 d postmortem. Longissimus thoracis from carcasses of Br- and Bo-sired steers had the highest (P < 0.05) Warner-Bratzler shear forces and the lowest (P < 0.05) tenderness ratings at 7 d postmortem. Adjust- ment of traits to various slaughter end points resulted in some changes in sire breed differences for carcass traits but had little effect on palatability traits. Car- casses from BB- and Pm-sired steers provided the most desirable combination of yield grade and longissimus palatability, but carcasses from HA-cross steers pro- vided the most desirable combination of quality grade and longissimus palatability. Tuli, a breed shown to be heat-tolerant, had longissimus tenderness similar to that of the non-heat-tolerant breeds and more tender longissimus than the heat-tolerant breeds in this study. studies have been reported by Koch et al. (1976, 1979, 1982b) and Wheeler et al. (1996). Breed differences in production traits are important genetic resources for improving beef production efficiency and meat composi- tion and quality. No single breed excels in all traits that are important to beef production. Diverse breeds are required to exploit heterosis and complementarity through crossbreeding and to match genetic potential with diverse markets, feed resources, and climates. Evaluation of carcass traits and meat palatability from different breeds or breed crosses is important in de- termining the potential value of alternative germplasm resources for profitable beef production. This paper re- ports on Cycle V of the GPE program that characterizes cattle breeds representing diverse biological types, in- cluding two new tropically adapted breeds compared to Brahman and two breeds with high frequencies of dou- ble muscling, for carcass and longissimus palatability traits that affect the quantity, quality, and value of pro- duction.