Forty (412±38 kg) and 41 (411±38 kg) Nellore-type
castrated males that originated from a commercial herd
with an average age of over 30 months (over four permanent
incisors) were used to generate the performance and
carcass trait data and the meat quality data, respectively.
After adaptation to a high-concentrate diet, the animals
were divided into three weight groups (light=376±
29 kg, intermediate=403±16 kg, and heavy=457±
17 kg), which represented the different growth potentials
before the beginning of the experimental feedlot period.
The animals within each weight group were randomly
assigned to the six treatments (three levels of vitamin D3
supplementation×two sunlight exposure conditions). The
unshaded and shaded pens occupied different sides of
the feedlot; one side of the feedlot had naturally lower insolation
than other side