Problem: An effective, single-injection, multi-year, GnRH contraceptive agent is needed to control reproduction in overabundant white-tailed deer populations. Method of study: Two GnRH conjugates, GonaConTM (GnRH–KLH) and GonaCon-BTM (GnRH–blue protein), were prepared in emulsion form as one-injection and two-injection immunocontraceptive vaccine formulations. In addition, the GnRH–KLH protein conjugate was lyophilized and suspended in AdjuVacTM adjuvant to produce a fifth vaccine formulation. Each formulation was administered to a group of five captive adult female white-tailed deer. Reproductive performance of treated female deer was monitored for 5 years to determine the comparative efficacy of the various treatments. Results: The longevity of the contraceptive response (2–5 years) was strongly influenced by the design of the conjugate antigen, the adjuvant used, and the delivery form of the vaccine. Conclusion: One-injection and two-injection formulations of GonaConTM and Gona- Con-BTM produced multi-year contraception in adult female white-tailed deer. GonaCon-BTM provided a longer lasting contraceptive effect
