Boneless rib steaks (L. dorsi muscle) from 26 two years old steers, 14 Polled Hereford, seven 3/4Hereford 1/4Nelore (3/4H1/4N) and five 5/8Hereford 3/8Nelore (5/8H3/8N), were collected 24 hs after slaughter and analysed for calpastatin activity and texture at the 1st day post mortem and at the 10th day of aging at 2o C. Calpastatin activity was determined by m-calpain inhibition assay and texture by shear force (Warner-Bratzler). Beef from 5/8H3/8N steers showed higher (p<0.05) calpastatin activity and shear force values than beef from HH and 3/4H1/4N steers in the 1st day. No differences (p>0.05) were detected in the same traits between groups HH and 3/4H1/4N. After 10 days of aging, there was a difference in calpastatin activity, although non-significant (p>0.05), amongst group 5/8H3/8N (1.57U/g) and the others (HH=1.23U/g; 3/4H1/4N=1.35U/g), and a significant difference in shear force between groups HH and 5/8H3/8N (3.67 and 5.00kg, respectively). It was concluded that the calpastatin activity determined 24 hs post mortem can be useful to predict the texture of beef, aged or not, in genetic improvement programs. Also, the increasing participation of Bos indicus genotype in the South Region herds of cattle, besides the productivity advantages, may result in beef of lower texture quality.
beef; Bos indicus; crossbreeding; texture; calpastatin