Efficacy of ERL-4221 as an ovotoxin for feral pigs (Sus scrofa)

Context. The expansion of feral pig populations across the United States has increased the occurrence of damage anddamage complaints.New techniques are needed tomore effectivelymanage feral pigdamage, including the development of fertility control agents. Aims. We aimed to assess the ovotoxic properties of ERL-4221 as a candidate fertility control agent for feral pigs. Methods. We conducted two palatability trials to determine ERL-4221 acceptance and one experimental trial with ERL4221 at the captive wildlife facility of Texas A&M University-Kingsville during 2008. Our experimental trial had three treatments, a control containing no ERL-4221, baits containing 16.0mg ERL-4221 kg bodyweight for 10 days, and baits containing 16.0mg ERL-4221 kg bodyweight for 20 days. Key results. Final body mass, total ovary mass, number of follicles and number of corpora lutea did not differ between treatments. Conclusions.Wedid not find it efficacious to orally deliver ERL-4221 to feral pigs to reduce fertility. Oral delivery is the most practical, cost-effective means of delivering fertility control agents to feral pigs and development of additional fertility control strategies are needed. Implications. Unless ovotoxic effects of ERL-4221 can be identified in feral pigs, along with a successful means of administration, other fertility control strategies may need to be explored, such as oocyte-secreted proteins that regulate follicular development. Additional keywords: ERL-4221, fertility control, oocyte, ovary, toxicity.