Carcass data from 5 years of a long-term,
rotational , crossbreeding project were used to
calculate heritabilities, genetic and phenotypic
correlations , and management effects and to
compare breeds for marbling, ribeye area, and
hot carcass weight. Angus, Brahman,
Charolais, Hereford, Polled Hereford, Gelbvieh,
and Simmental breeds were involved. Sixty
percent of the steer calves were fed as calves
and 40% as yearlings. Heritabilities were .40
for marbling, .46 for ribeye area, and .51 for
carcass weight. Genetic and phenotypic correlations
were high between carcass weight and
ribeye area but low between marbling and the
other traits. Steers fed as calves had more marbling
and lighter carcasses than steers fed as
yearlings. Higher percentages of Gelbvieh or
Brahman breeding resulted in lower (P<.05)
marbling . Increased percentage of Charolais
and Simmental breeding increased (P<.05)
ribeye area and tended to increase carcass
weight without reducing marbling.
