The Effect of Immunocontraception on the Behavior and Reproduction of White-Tailed Deer

Abstract

Behavioral and reproductive consequences of porcine zona pellucida (PZP) immunocontraception were examined in a herd of white-tailed deer (Odocoileus virginianus; n = 30) from September 1992 to September 1994. Does were captured from a wild population and placed within either of 2 large (32-ha total) wooded enclosures. Does were administered either: (1) a single injection containing PZP-emulsified in Freund's complete adjuvent (FCA) and microsphere-encapsulated PZP; (2) 2 injections of PZP-emulsified in FCA and Freund's incomplete adjuvant (FIA), 4 weeks apart; or (3) no treatment. Mature, spermic bucks (n = 5) were added to each pasture 4 weeks after the final PZP treatment, and reproductive behaviors and fawn production were observed for 2 years. Immunocontracepted females exhibited increased activity compared to non-treated females, presumably reflecting an increased number of estrus intervals. Similarly, enclosure bucks exhibited an extended breeding season compared to males in the surrounding wild population. The 2-injection PZP regimen provided effective contraception during both years of the study. The 1-injection PZP regime provided effective contraception only during the second year, following administration of a PZP booster. Histological evaluations of ovaries failed to reveal among-group differences in ovarian architecture. Contracepted-nonpregnant does gained significantly more weight than control females during the study.