ABSTRACT
The effect of chromium yeast on antirabies humoral immune response was evaluated in Nelore heifers. Sixty heifers (Bos indicus) aged about 2 to 5 years were fed on Brachiaria decumbens pasture and allowed ad libitum access to mineral salt and water. They were randomly distributed into one of 4 groups (15 animals each): control animals (Gc) received chromium-free mineral salt; the other groups received 8.5, 17 and 34 mg chromium/salt kg, thus constituting groups G8.5, G17 and G34, respectively. In the first day of the experiment (day 0), all the heifers were vaccinated with commercial rabies vaccines and blood was sampled on days 0, 30, 60 and 90. Antirabies antibody titers were determined by virus neutralization test in mice. Results showed that heifers of G17 increased significantly the antirabies antibody; however, only in G34 was the titer of protective antibodies higher on the 90th day after vaccination. These results demonstrate that chromium increases neutralizing antirabies antibody titers, and that the best concentration is 34 mg Cr/kg mineral salt.
KEY WORDS
Chromium; rabies; vaccine; heifers; antirabies antibody