The aim of this study was to evaluate the effect of immunocastration of Nellore male and
Holstein-Zebu cattle receiving supplement at a rate of 1 and 2% of body weight during the
growing and finishing phases, respectively. Thirty-six male cattle (217.80 ± 20.58 kg) were
distributed following a completely randomized design with a 2 × 2 factorial arrangement into
two genetic groups (Nellore and Holstein-Zebu) and two sex classes (intact and
immunocastrated). Immunocastration reduced the circumference, width, length, weight and
volume of the testicles. The average daily weight gain (DWG) of the intact and
immunocastrated animals was similar during the growing phase, but at the finishing phase the
DWG was higher for the intact animals. The genetic groups did not altered DWG and the hot
carcass weight and cold carcass weight, however Nellore animals showed higher hot carcass
yield and cold carcass yield. The glucose, creatinine and aspartate aminotransferase
concentrations were higher for the Nellore during growth. The urea concentration showed
interaction between the genetic groups and the sexual conditions at finishing.
Immunocastration increased the subcutaneous fat thickness (SFT) in the Holstein-Zebu, but
had no effect on SFT in Nellore animals. The intact males had larger Longissimus lumborum
area, muscle proportion and forequarter. On the other hand, the immunocastrated males had
fat in carcass and meat higher and shear force of meat lower, lightness (L*), redness (a*) and
yellowness (b*) of meat and b* of fat higher. Male dairy cattle show performance, carcass and
meat characteristics similar to that of Nellore males and can be used for beef production, but
their carcass yield is lower. Immunocastration reduces performance, as a result termination of
intact males is more economically viable. However, the immunocastration increases the fat in
the carcass, the tenderness and improves the visual aspects meat. Therefore, the
immunocastration should only be used when a differentiated payment exists for castrated
animals at slaughter.
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