Growth and carcass characteristics of nellore, simmental and crossbreeds young bulls

Abstract

This study investigated the muscular growth and the adipose tissue deposition of 72 Nellore, Simental, Simbrasil and ½ Simental x Nellore cattle, in feedlot, at 8 months old and an initial weight of 287kg, allocated, at random, in stalls with capacity of six animals, each. Later, the animals were slaughtered, with final weight above 450 kg. Longissimus dorsi muscle area (LMA) and subcutaneous fat thickness (FT) measurements were taken twice by ultrasound. At the beginning of the experiment, the animals age were not significantly different, however, Nellore animals showed smaller LMA (P<0.01) than the pure Simmental and Simbrasil. The highest values of LMA found for the other genetic groups were in accordance with the highest weaning weights (Nellore, 241.4kg; pure Simmental, 300.3kg; Simbrasil, 368.8Kg; ½ Simmental, 268.5Kg). The crossbred animals had the highest lean gain (P<0.05), which corresponded to the highest gains (Nellore, 1.06kg/d; Simmental, 1.67kg/d; Simbrasil and ½ Simmental, 1.22kg/d) and to the highest (P<0.05) values of LMA. The use of Nellore breed in feedlot system may not be economically viable, since it took 60 days more than the other genetic groups to reach the target weight, LMA and FT. The ultrasound was efficient on estimating tissue growth and showed significant differences among genetic groups for LMA and FT, which helps on determining the ideal slaughter spot.