Abstract

In August 1997 three 9-month-old Red x Wapiti stags were inoculated intravenously with Brucella ovis. Between October 1997 and June 1998 these three stags were grazed with 8 control stags of a similar age and 10 one-year-old Perendale rams, which had been confirmed free from B. ovis infection before mixing. At monthly intervals the 11 stags and 10 rams were blood sampled for B. ovis serology and when infection was suspected, this was confirmed by bacterial culture of a semen sample. Two of the three artificially infected stags became persistently infected with B. ovis and shed the organism in their semen. They remained positive to the B. ovis complement fixation (CF) serological test throughout the trial. The CF titre fell below the positive cut-off level 4 months after inoculation in the other artificially infected stag which did not develop persistent B. ovis infection. During April and May 1998, 7 months after mixing with the artificially infected animals, B. ovis infection was identified in 4 of the 8 control stags. There was no evidence of B. ovis transmission to the control rams. The trial demonstrated the rapid transmission of B. ovis infection between young stags during the rut. This would suggest that sexual activity is important for B. ovis to spread, although the exact means of transmission could not be determined. Rams grazed in conjunction with B. ovis - infected stags have a lower risk of becoming infected.

DM, West, KJ Stafford, ND Sargison, SG Fenwick, and MP Reichel

Proceedings of the New Zealand Society of Animal Production, Volume 59, , 134-136, 1999