Foaling rates in feral horses treated with the immunocontraceptive porcine zona pellucida

Ransom, Jason I.; Roelle, James E.; Cade, Brian S.; Coates-Markle, L.; Kane, Albert J.

doi:10.1002/wsb.66

Cited by 19 publications

(22 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Free-roaming female feral horses were formerly treated with PZP for 1–5 years at all three study sites [16]. The conventional liquid form of PZP was designed to provide infertility through only a single year per inoculation, and this form was used at Pryor Mountain beginning in 2001 and at Little Book Cliffs beginning in 2002.…”

Section: Methodsmentioning

confidence: 99%

“…The time-release form of PZP consisted of a single inoculation of liquid PZP simultaneously applied with 3 pellets designed to release PZP in a bolus fashion at 1, 3, and 12 months, for a total of 22 months of targeted infertility [16]. All females in the treatment group at McCullough Peaks received time-release PZP in October 2004.…”

Section: Methodsmentioning

confidence: 99%

“…This transient contraceptive may last 10–22 months per application, depending on the formulation and species [6], [15], [16]. The management appeal of PZP is that it is expected to be reversible, is relatively easy to apply, and has few known contraindications for individuals [17], [18].…”

Section: Introductionmentioning

confidence: 99%

“…The individual-level efficacy and behavioral implications of PZP were previously investigated in three free-roaming feral horse populations in the western U.S. [16], [23]. We have now followed each individual female in these same populations past their targeted infertile years to further evaluate return to fertility, phenology of births, and neonate survival.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Contraception can Lead to Trophic Asynchrony between Birth Pulse and Resources

2013

Self Cite

View full text Add to dashboard Cite

Abiotic inputs such as photoperiod and temperature can regulate reproductive cyclicity in many species. When humans perturb this process by intervening in reproductive cycles, the ecological consequences may be profound. Trophic mismatches between birth pulse and resources in wildlife species may cascade toward decreased survival and threaten the viability of small populations. We followed feral horses (Equus caballus) in three populations for a longitudinal study of the transient immunocontraceptive porcine zona pellucida (PZP), and found that repeated vaccinations extended the duration of infertility far beyond the targeted period. After the targeted years of infertility, the probability of parturition from post-treated females was 25.6% compared to 64.1% for untreated females, when the data were constrained only to females that had demonstrated fertility prior to the study. Estimated time to parturition increased 411.3 days per year of consecutive historical treatment. Births from untreated females in these temperate latitude populations were observed to peak in the middle of May, indicating peak conception occurred around the previous summer solstice. When the post-treated females did conceive and give birth, parturition was an estimated 31.5 days later than births from untreated females, resulting in asynchrony with peak forage availability. The latest neonate born to a post-treated female arrived 7.5 months after the peak in births from untreated females, indicating conception occurred within 24–31 days of the winter solstice. These results demonstrate surprising physiological plasticity for temperate latitude horses, and indicate that while photoperiod and temperature are powerful inputs driving the biological rhythms of conception and birth in horses, these inputs may not limit their ability to conceive under perturbed conditions. The protracted infertility observed in PZP-treated horses may be of benefit for managing overabundant wildlife, but also suggests caution for use in small refugia or rare species.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Contraception can Lead to Trophic Asynchrony between Birth Pulse and Resources

2013

Self Cite

View full text Add to dashboard Cite

show abstract

“…Adjuvants, which are inorganic or organic chemicals, macromolecules or entire cells of specific killed bacteria, are typically used to amplify the immune response to an antigen. The factors that affect effectiveness, longevity and side effects of immunocontraceptive vaccines include species, gender, age, individual variation in immunocompetence, as well as the active immunogen, formulation, delivery system and dose and type of adjuvant (Miller et al 2008aHolland et al 2009;Kirkpatrick et al 2011;Ransom et al 2011). The most studied immunocontraceptives in wildlife are zona pellucida (ZP) and GnRH vaccines ( Table 1).…”

Section: Immunocontraceptive Vaccinesmentioning

confidence: 99%

Fertility control to mitigate human–wildlife conflicts: a review

2014

View full text Add to dashboard Cite

Abstract. As human populations grow, conflicts with wildlife increase. Concurrently, concerns about the welfare, safety and environmental impacts of conventional lethal methods of wildlife management restrict the options available for conflict mitigation. In parallel, there is increasing interest in using fertility control to manage wildlife. The present review aimed at analysing trends in research on fertility control for wildlife, illustrating developments in fertility-control technologies and delivery methods of fertility-control agents, summarising the conclusions of empirical and theoretical studies of fertility control applied at the population level and offering criteria to guide decisions regarding the suitability of fertility control to mitigate human-wildlife conflicts. The review highlighted a growing interest in fertility control for wildlife, underpinned by increasing numbers of scientific studies. Most current practical applications of fertility control for wild mammals use injectable single-dose immunocontraceptive vaccines mainly aimed at sterilising females, although many of these vaccines are not yet commercially available. One oral avian contraceptive, nicarbazin, is commercially available in some countries. Potential new methods of remote contraceptive delivery include bacterial ghosts, virus-like particles and genetically modified transmissible and non-transmissible organisms, although none of these have yet progressed to field testing. In parallel, new species-specific delivery systems have been developed. The results of population-level studies of fertility control indicated that this approach may increase survival and affect social and spatial behaviour of treated animals, although the effects are species-and context-specific. The present studies suggested that a substantial initial effort is generally required to reduce population growth if fertility control is the sole wildlife management method. However, several empirical and field studies have demonstrated that fertility control, particularly of isolated populations, can be successfully used to limit population growth and reduce human-wildlife conflicts. In parallel, there is growing recognition of the possible synergy between fertility control and disease vaccination to optimise the maintenance of herd immunity in the management of wildlife diseases. The review provides a decision tree that can be used to determine whether fertility control should be employed to resolve specific human-wildlife conflicts. These criteria encompass public consultation, considerations about animal welfare and feasibility, evaluation of population responses, costs and sustainability.

show abstract

Estimating Abundance and Simulating Fertility Control in a Feral Burro Population

Gedir

Cain

Lubow³

et al. 2021

J Wildl Manag

View full text Add to dashboard Cite

Overabundant populations of feral equids are negatively affecting rangelands in the western United States. To better manage these populations, robust estimates of abundance and demographic rates and cost-effective methods of reducing abundance are necessary. From August 2015 to April 2017, we estimated the abundance of feral burros (Equus asinus) at the Fort Irwin National Training Center (NTC; California, USA) using a double-observer-sightability aerial survey method; captured, radio-collared, and inoculated female burros with porcine zona pellucida (PZP), an immunocontraceptive control agent; estimated female demographic rates; and used matrix population models to simulate how changes in demographic and PZP delivery rates would influence burro abundance. We estimated there were 690 (95% CI = 618-752) feral burros within the surveyed area, but these are part of a much larger population that is not geographically isolated from those in the survey area. Sighting probabilities ranged from 0.19-0.98 and were most strongly influenced by distance from observer and group size. We estimated age-specific demographic rates at the NTC and compiled mean rates across burro populations in arid environments from the literature. Mean fecundity varied from 0.17 to 0.58 foals/adult female with younger females having lower fecundity. Mean survival was 0.90 for foals, 0.98 for yearlings, and 0.96 for adults. The PZP vaccine treatment strategies that suppressed fertility for up to 10 years predicted that burro abundance would be reduced by 67-88% after 15 years (compared with no treatment), but none of these strategies resulted in population extirpation. Population growth rates shifted from increasing to decreasing at adult survival rates below 0.84 and the population was predicted to become extirpated when adult survival declined to <0.60. In the absence of other methods to reduce burro numbers, our findings indicate that current formulations of PZP immunocontraception, which require multiple doses, would be inadequate for controlling population growth rates at the NTC. Our fieldwork also highlighted the difficulty of administering PZP vaccination to large, free-ranging animals. Development of longer-term fertility reduction agents or more efficient vaccine delivery techniques would likely improve the efficacy of fertility control for overabundant ungulate populations. Lack of geographic closure (physical barriers to migration) further complicated efforts to reduce burro numbers.

show abstract

Foaling rates in feral horses treated with the immunocontraceptive porcine zona pellucida

Cited by 19 publications

References 27 publications

Contraception can Lead to Trophic Asynchrony between Birth Pulse and Resources

Contraception can Lead to Trophic Asynchrony between Birth Pulse and Resources

Fertility control to mitigate human–wildlife conflicts: a review

Estimating Abundance and Simulating Fertility Control in a Feral Burro Population

Contact Info

Product

Resources

About