EFFECTS OF THE IMMUNOCONTRACEPTIVE GONACON ON PREGNANCY IN BRUCELLA-SEROPOSITIVE AMERICAN BISON (BISON BISON).

The purpose of this study was to determine if the number of pregnancies in naturally infected Brucella abortus–positive bison (Bison bison) cows would be reduced over a period of 5 yr after one treatment with 3000 mg gonadotropin-releasing hormone immunocontraceptive (GonaCon) compared to a similar group of naturally infected B. abortus–positive bison cows not treated with GonaCon. In each of the 5 yr, GonaCon-treated cows produced fewer offspring in relation to number of cows than the nontreated cows. Fisher's Exact test comparing offspring produced during the first reproductive season showed a significant difference between the two groups (P=0.0028). Differences in number of calves produced in GonaCon-treated and control groups were also noted in remaining years, but statistics were not applied because of data constraints. These data indicate that one treatment with GonaCon in brucellosis-seropositive female bison reduced pregnancies over five reproductive years. Thus, immunocontraception could potentially be used to manage brucellosis in affected herds. [ABSTRACT FROM AUTHOR]