PERFORMANCE AND CARCASS CHARACTERISTICS OF STEERS FROM TWO GENETIC GROUPS, FINISHED IN FEEDLOT AND SLAUGHTERED AT DIFFERENT WEIGHTS

Eighteen 3/4 Nellore-1/4 Canchim and 3/4 Nellore-1/4 Caracu steers with an initial live weight of 312 and 303kg, respectively, and 22 months of age, were used to evaluate the effects of the genetic groups and different slaughter weight (430, 470 and 530kg) on the dry matter intake, weight gain, feed conversion, loin eye area and fat thickness. The animals were confined and allotted to a completely randomized design, in a 2 X 3 factorial arrangement (genetic groups and slaughter weight), with three replicates. The animals were fed with 43:57 forage to concentrate ratio (dry matter basis) based on sorghum silage and concentrate and weighted at four weeks intervals after 18 hours fasting and slaughtered as they reached the pre-established weights. There was no significant interaction between genetic group and weight at the slaughter time and there was no effect of the genetic group for all the variables studied. However, larger loin eye area (adjusted for 100kg of cold carcass) was observed in the animals slaughtered earlier (27,68cm(2) at 430kg) and larger fat thickness was verified in the animals slaughtered lately (10,58mm at 530kg). All the carcass produced attended Brazilian market demands of weight and finishing degree.