Porcine zona pellucida vaccine immunocontraception of African elephant (Loxodonta africana) cows: A review of 22 years of research

Abstract

Background: The native porcine zona pellucida (pZP) vaccine has been successfully used for immunocontraception of wild horses, white-tailed deer and approximately 90 zoo species for more than 25 years.Objectives: To provide proof of concept and test contraceptive efficacy of pZP in African elephants. Once completed, test the population and behavioural effects on cows in the Greater Makalali Private Game Reserve (GMPGR). Following the GMPGR, test efficacy, population effects, safety and reversibility in 25 reserves with populations ranging from 9 to 700 elephants.Method: Histological sections were reacted with anti-pZP antibodies to provide proof of concept. From 1996 to 2000, 21 and 10 cows were treated with pZP vaccine in the Kruger National Park (KNP) and monitored for pregnancy. Population effects of pZP with Freund’s adjuvants (three vaccinations in Year 1 with one annual booster) were studied on 18 cows in the GMPGR. Another six game reserves with a total of 90 cows were added to the project. The project was then expanded to include another 18 reserves.Results: Binding of anti-pZP antibodies to elephant zona proteins was demonstrated in vitro. The KNP provided efficacy results of 56% and 80%, respectively. The contraceptive efficacy in the GMPGR and additional six reserves was 100% following calving of pregnant cows. Safety and lack of impact on social behaviour were demonstrated. In larger populations, efficacy was 95%.Conclusion: Contraceptive efficacy and safety of pZP vaccine could be demonstrated in small to large populations. The methodology is now being implemented in approximately 800 cows on 26 reserves across South Arica.

Elephant rewilding affects landscape openness and fauna habitat across a 92‐year period

“…Elephant restorations may compromise biodiversity locally in some instances (Cook et al, 2017; Midgley et al, 2020), and active population control may be argued in these cases (Bertschinger et al, 2018), for example, when elephants completely prohibit tree recruitment throughout a conservation area (Cook et al, 2017). However, this is a limited overall challenge due to the widespread depression of elephant populations (Chase et al, 2016).…”

Out of the stable: Social disruption and concurrent shifts in the feral mare (Equus caballus) fecal microbiota

“…Shackleford mares treated with PZP change groups more often and join more groups than do untreated mares (Madosky et al, 2010; Nuñez et al, 2009); these behavioral effects can be long‐lasting, even after treatment has ended (Nuñez et al, 2017). PZP is used to control animal populations around the world, including white‐tailed deer ( Odocoileus virginianus ; McShea et al, 1997), elk ( Cervus canadensis ; Heilmann et al, 1998), the endangered African elephant ( Loxodonta africana ; Bertschinger et al, 2018), and Przewalski's horse ( Equus ferus przewalskii ; Kerekes et al, 2021). Our previous work on Shackleford has shown that fewer contraceptive treatments, over longer periods of time can help to maintain more natural behavior and reproductive physiology (Nuñez et al, 2017) and reduce stress (Nuñez et al, 2014); given the present data, such management practice could also potentially maintain important symbiotic relationships in treated mares.…”

Impacts of African savannah elephants (Loxodonta africana) on tall trees and their recovery within a small, fenced reserve in South Africa

“…Elephant bulls have been shown to cause greater impacts to vegetation compared with cows as they are larger bodied and have more destructive tendencies, especially when in musth (Greyling, 2004). The success of contraception as a management tool to control population numbers has been shown in several small reserves in South Africa, including the Greater Makalali Private Game Reserve and Tembe Elephant Park (Bertschinger et al, 2018). Contraceptives were also administered to bull elephants in 2016 in the reserve considered in this study.…”