This trial wasconducted to evaluate some beef quality attributes of Nellore, F1Simmental × Nellore and F1 Angus × Nellore steers finishedon feedlot. The effects of feeding regime and genetic group on shear force,thawing losses, cooking (leak + evaporation) losses, total losses and musclefiber type, as well as carcass pH and temperature during 24 h of chilling wereevaluated. There was a genetic group effect on shear force, where the beef fromF1 Simmental × Nellore and F1 Angus × Nelloreanimals had lower values than Nellore animals. Beef of the animals fed the dietswith 1% and 2% of body weight on concentrated lost more liquid than the meatof the animals fed at maintenance during thawing and when considering totallosses. During cooking there was a difference among the feeding regimes fordrip losses which were greater on the animals fed the diet of 1% of body weighton concentrate, followed by the 2% diet and, finally, by the animals fed atmaintenance. The muscle of the Nellore steers had larger proportion of intermediatefibers and lower proportion of oxidative fibers than the crossbred animals.The proportion of glycolytic fibers was not influenced by genetic group. TheNellore animals had larger proportion of fibers of fast contraction and smallerproportion of fibers of slow contraction when compared with the crossbred animals.Feeding regime did not influence the proportion of muscular fibers or shearforce. Nellore cattle produce tougher beef than crossbred Simmental × Nelloreor Angus × Nellore, although all of them have the potential to producean acceptable beef when slaughtered at young age. Feed restriction up to 90days is not enough to cause modification on muscle fiber frequencies, then notaffecting beef quality.
