Factors affecting prolactin secretion in the African elephant

Prolactin (PRL) is a peptide hormone that is involved in a number of diverse physiologic roles, particularly with respect to reproduction, including: influencing sexual and parental behaviors, onset of puberty, regulation of seasonal reproduction, follicular maturation, ovulation, luteinization and corpus luteum (CL) function, steroidogenesis, mammary gland development and lactation, testicular and spermatozoal function, and immunomodulation of ovarian processes. Little is known about PRL's role in elephant reproduction. The present research was conducted to determine seasonal changes in PRL secretion in non-pregnant female African elephants. A corollary objective was to examine the potential functional interrelationships between secretions of PRL, cortisol and progesterone. Weekly blood samples for 18 months were taken from four female African elephants and the sera were analyzed by radioimmunoassay for progesterone, cortisol, and PRL concentrations. Estrous cycles averaged 14 weeks in length, and estrous cycle synchronicity was evident between pairs of elephants. The luteal phase was defined by serum concentrations of progesterone consistently above 200 pg/ml, and averaged 9 weeks in length (range: 5-12 weeks) with a mean (± SE) concentration of 750.3 ± 171.9 pg/ml. The follicular phase was defined by serum concentrations of progesterone consistently below 200 pg/ml, and averaged 5 weeks in length (range: 4-8 weeks) with a mean concentration of 103.1 ± 17.5 pg/ml. Mean (± SE) serum concentration of cortisol was 5.7 ± 1.3 ng/ml (range: 1.4-19.3 ng/ml), and concentrations of this adrenal steroid were negatively correlated with progesterone concentrations (r=-0.15; p<0.01). Serum concentrations of PRL averaged 3.91 ± 0.69 ng/ml (range: 0.84-15.8 ng/ml), were significantly lower during the luteal phase (p<0.0001; t-test), and were positively correlated with serum concentrations of cortisol (r=0.14; p<0.05). There was no significant effect of season on PRL concentrations. One of the elephants appeared to be hyperthyroid, but since removing her values from the data set did little to affect overall means, they were included in all of the calculations. These data suggest that stress may affect secretion of PRL in elephants, and cortisol and PRL may affect reproductive potential in elephants by altering luteal function. While this study did not demonstrate a seasonal effect on PRL secretion, it cannot be concluded that there is none because the reproductive effects of photoperiod are not always easy to detect. The higher serum concentrations of PRL detected during the follicular phase suggest that this hormone may play a role in modulating ovarian function in elephants during this stage of the estrous cycle

Fertility Control Options for Management of Free-roaming Horse Populations

The management of free-roaming horses (Equus ferus) and burros (E. asinus) in the United States has been referred to as a “wicked problem” because, although there are population control options, societal values will ultimately determine what is acceptable and what is not. In the United States, free-roaming equids are managed by different types of organizations and agencies, and the landscapes that these animals inhabit vary widely in terms of access, size, topography, climate, natural resources, flora, and fauna. This landscape diversity, coupled with contemporary socioeconomic and political environments, means that adaptive management practices are needed to regulate these free-roaming populations. The Bureau of Land Management (BLM) currently manages free-roaming equids on 177 herd management areas in the United States by applying fertility control measures in situ and/or removing horses, which are either adopted by private individuals or sent to long-term holding facilities. The BLM off-range population currently includes \u3e50,000 animals and costs approximately $50 million USD per year to maintain; on-range equid numbers were estimated in March 2022 to be approximately 82,384. On-range populations can grow at 15–20% annually, and current estimates far exceed the designated appropriate management level of 26,715. To reduce population recruitment, managers need better information about effective, long-lasting or permanent fertility control measures. Because mares breed only once a year, fertility control studies take years to complete. Some contraceptive approaches have been studied for decades, and results from various trials can collectively inform future research directions and actions. Employing 1 or more fertility control tools in concert with removals offers the best potential for success. Active, iterative, cooperative, and thoughtful management practices can protect free-roaming horses while simultaneously protecting the habitat. Herein, we review contraceptive vaccines, intrauterine devices, and surgical sterilization options for controlling fertility of free-roaming horses. This review provides managers with a “fertility control toolbox” and guides future research

Single-Dose, Multi-Year Immunocontraception using SpayVac\u3csup\u3e®\u3c/sup\u3e

Managing populations of certain species such as free-ranging horses (Equus caballus) is a significant challenge, with animal-welfare, environmental, sociological, public policy, and economic dimensions. Immunocontraception is a useful tool, but vaccines must have multi-year efficacy to be technically feasible and cost-effective. SpayVac® has demonstrated single-dose, long-term contraceptive efficacy in several species. Grey seals (Halichoerus grypus) experienced an 80-85% decrease in fertility for at least 10 years post-treatment. No fallow deer (Dama dama) treated with SpayVac became pregnant for 3 years following vaccination. In a field trial with white-tailed deer (Odocoileus virginianus), no treated does became pregnant during the first 2 years post-inoculation, and 13% became pregnant during the year 3 compared to 78-100% of control does. A captive trial with white-tailed deer demonstrated contraceptive efficacy of 80–100% for 5 years with a single injection of SpayVac. Mares exhibited pregnancy rates of 0, 17, 17, and 17%, respectively, 1–4 years after treatment with SpayVac, compared to 75-100% for controls. In another study, the fertility rate for treated mares was 13, 47, 43, and 43% compared to 100, 98, 100, and 83% in controls for 1–4 years post-vaccination, respectively. Horses have seven different IgG isotypes, and we recently demonstrated that SpayVac preferentially stimulates production of IgG4/7 antibodies, which may contribute to its long-term immunocontraceptive efficacy. Vaccination methods, long-term population effects of immunocontraception, herd health and nutritional status, and population modeling scenarios should all be considered, when developing vaccination strategies for different species

Twenty Years of SpayVac® Research: Potential Implications for Regulating Feral Horse and Burro Populations in the United States

There are currently \u3e75,000 feral horses (Equus ferus caballus) and burros (E. asinus ) on U.S. public lands, yet the Appropriate Management Level (AML) is set at just under 27,000. Wildlife managers, conservation biologists, and livestock ranchers are concerned about the impacts that these free-ranging horses have on shared rangelands. Immunocontraceptive vaccines may have the greatest potential to regulate horse population numbers once AML is reached; however, the vaccine must have multi-year efficacy to be both technically feasible and cost-effective. Immunocontraception based on porcine zona pellucida (PZP)-specific antigens is highly tissue-specific, targeting the ova, and blocking sperm binding through antibody occupation of ZP receptors on the ova. ZonaStat-H and PZP-22 are PZP-based vaccines; however, their contraceptive efficacy does not last long enough to meet management needs. SpayVac® achieves multi-year efficacy with a single dose, without boosters, because the PZP antigens are encapsulated within liposomes (multi-layered, submicroscopic vesicles), which gradually release PZP glycoproteins to antigen-presenting cells over an extended period of time. We review results from SpayVac trials in horses and other species to deepen our understanding of how the vaccine works and how it may best be applied to regulate free-ranging horse populations at AML. We examine 3 studies in horses, which used different SpayVac formulations and delivery methods, to learn more about the relationship between antibody titers and contraceptive efficacy, as well as potential mechanisms of action (e.g., preferential stimulation of IgG4/7 antibody isotypes). Additional research to explore possible effects of injection site location, antigen purity, role of PZP antibodies, and different formulations (e.g., dose, adjuvant) is needed for efficacious application to free-ranging herds

The elephant's foot : prevention and care of foot conditions in captive Asian and African elephants

vii+163hlm.;25c

Fertility Control Options for Management of Free-roaming Horse Populations (Abstract)

The management of free-roaming horses (Equus ferus) and burros (E. asinus) in the United States has been referred to as a “wicked problem” because, although there are population control options, societal values will ultimately determine what is acceptable and what is not. In the United States, free-roaming equids are managed by different types of organizations and agencies, and the landscapes that these animals inhabit vary widely in terms of access, size, topography, climate, natural resources, flora, and fauna. This landscape diversity, coupled with contemporary socioeconomic and political environments, means that adaptive management practices are needed to regulate these free-roaming populations. The Bureau of Land Management (BLM) currently manages free-roaming equids on 177 herd management areas in the United States by applying fertility control measures in situ and/or removing horses, which are either adopted by private individuals or sent to long-term holding facilities. The BLM off-range population currently includes &gt;50,000 animals and costs approximately $50 million USD per year to maintain; on-range equid numbers were estimated in March 2022 to be approximately 82,384. On-range populations can grow at 15-20% annually, and current estimates far exceed the designated appropriate management level of 26,715. To reduce population recruitment, managers need better information about effective, long-lasting, or permanent fertility control measures. Because mares breed only once a year, fertility control studies take years to complete. Some contraceptive approaches have been studied for decades, and results from various trials can collectively inform future research directions and actions. Employing one or more fertility control tools in concert with removals offers the best potential for success. Active, iterative, cooperative, and thoughtful management practices can protect free-roaming horses while simultaneously protecting the habitat. Herein, we review contraceptive vaccines, intrauterine devices, and surgical sterilization options for controlling fertility of free-roaming horses. This review provides managers with a “fertility control toolbox” and guides future research