Effects of Porcine Zona Pellucida Immunocontraception on Mare Body Condition and Foaling Season Length in Two Western Wild Horse Populations.
Abstract: Wildlife managers and the public have expressed considerable interest in the use of contraception to help manage the populations of wild horses and burros (Equus caballus and E. asinus). Field testing has shown that two preparations of the porcine zona pellucida (PZP) vaccine, a simple emulsion (ZonaStat-H) and PZP-22 (which supplements ZonaStat-H with a controlled-release component) effectively prevent pregnancy in individual mares and can substantially reduce population foaling rates. To determine whether some PZP preparations might have secondary effects that harm treated mares or their foals, we examined the effects of PZP-22 vaccinations and the follow-up boosters of either PZP-22 or ZonaStat-H on adult female body condition, foaling season, and foal mortality in two wild horse herds in the western USA, Cedar Mountains Herd Management Area, Utah (CM; 2008-2015), and Sand Wash Basin Herd Management Area, Colorado (SWB; 2008-2014). At both sites in every study year, summer body condition scores improved faster in mares without foals than mares with foals (p < 0.001; CM, n = 234; SWB, n = 172), but PZP treatments did not affect mare body condition apart from their contraceptive effects. Births to mares treated with PZP within the previous three years were delayed and spread out over the foaling season, but foal mortality rates through the first and second year were low, unrelated to date of birth, and virtually identical for the foals of PZP-treated and untreated mothers (all comparisons n.s.; CM, n = 775, SWB, n = 640). Thus, in these two populations, we found no evidence that changes in reproductive timing associated with PZP treatments were harmful to either mares or foals.
Publication Date: 2024-12-09 PubMed ID: 39682515PubMed Central: PMC11640156DOI: 10.3390/ani14233550Google Scholar: Lookup
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- Journal Article
Summary
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This research article is about the study of the effectiveness and potential side effects of porcine zona pellucida (PZP) vaccines in controlling wild horse and burro populations, by observing the body conditions, birth seasons, and foal mortality rates of vaccinated mares.
Objective of the Study
- The chief goal of the research was to observe potential side effects of PZP vaccinations, specifically PZP-22, on wild horse populations by studying the body conditions, fertility durations, and foal death rates of vaccinated mares.
Methodology
- The researchers carried out their studies on two wild horse populations residing in Cedar Mountains Herd Management Area, Utah and Sand Wash Basin Herd Management Area, Colorado from the year 2008 to 2015 and 2008 to 2014 respectively.
- The study subjects were mares that were either vaccinated with PZP or not, along with their foals.
- They compared the summer body conditions of mares without foals and those with foals.
- The births from the mares that were treated with PZP within three years prior were also monitored to see the effect on the timing and spread throughout the foaling season.
- The researchers also monitored the mortality rate of foals born within the first and second year of their lives and checked for any correlation with the date of birth.
Findings
- The study found that the body condition scores during summer improved faster in mares without foals as compared to those with foals.
- However, the vaccination (PZP treatment) did not affect the body conditions of the mares apart from presenting contraceptive effects.
- Births to mares that were treated with PZP within the previous three years were found to be delayed and spread throughout the foaling season.
- The mortality rates of the foals during the first and second year of life were found to be low, unconnected to the date of birth, and almost equal for both sets of foals born to treated and untreated mothers.
- Therefore, the research did not find any evidence suggesting that changes in reproductive timing due to PZP treatments had any harmful effects on either mares or their foals.
Cite This Article
APA
Rutberg AT, Grams KA.
(2024).
Effects of Porcine Zona Pellucida Immunocontraception on Mare Body Condition and Foaling Season Length in Two Western Wild Horse Populations.
Animals (Basel), 14(23).
https://doi.org/10.3390/ani14233550 Publication
Researcher Affiliations
- Cummings School of Veterinary Medicine at Tufts University, 200 Westboro Road, North Grafton, MA 01536, USA.
- Science and Conservation Center, 2100 South Shiloh Road, Billings, MT 59106, USA.
Grant Funding
- n/a / Annenberg Foundation
- n/a / Humane Society of the United States
Conflict of Interest Statement
The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.
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