Effects of Seven Consecutive Years of Porcine Zona Pellucida Contraception on Ovarian Function in Feral Mares1

Kirkpatrick, Jay F.; Naugle, Ricky E.; Liu, I.K.M.; Bernoco, M.; Turner, John W.

doi:10.1093/biolreprod/52.monograph_series1.411

Cited by 31 publications

(38 citation statements)

References 22 publications

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“…Kirkpatrick et al (1992) found that Assateague mares treated with PZP for 3 years excreted reduced concentrations of urinary estrone conjugates compared to currently untreated mares, and the absence of a luteal phase increase in progesterone metabolites suggested that some treated females were anovulatory. In a later study, Kirkpatrick et al (1995) found that the percentage of mares excreting normal range concentrations of urinary estrone conjugates declined from 80% for mares treated with PZP for 1 year to 0% for mares treated for 7 years. Hormonal assessments of mares conducted after 1, 2, 3, 6, and 7 years of annual PZP administration revealed that 50% of the treated mares excreted reduced concentrations of urinary estrone conjugates, although most females continued to cycle at least intermittently (Kirkpatrick et al, 1995).…”

Section: Discussionmentioning

confidence: 91%

“…Among horses, no abnormalities in ovarian histology were documented after 1 year of treatment with PZP (Liu, Bernoco, & Feldman, 1989); however, feral mares on PZP for 3 consecutive years demonstrated diminished urinary estrogen conjugate levels and lower ovulation rates than untreated mares (Kirkpatrick et al, 1992). The decline in estrogen excretion and ovulation rate continued in mares that had been on PZP for up to 7 years (Kirkpatrick et al, 1995). These data suggest that, in addition to preventing sperm binding, PZP immunocontraception also may have an adverse impact on ovarian follicular development or function, or both.…”

mentioning

confidence: 94%

“…However, many studies of laboratory and free-ranging animals have shown that PZP treatment can cause abnormalities in ovarian steroid production and histology (Bamezai, Das, & Talwar, 1986;Gulyas, Gwatkin, & Yuan, 1983;Hasegawa et al, 1992;Kirkpatrick, Liu, Turner, Naugle, & Keiper, 1992;Kirkpatrick, Naugle, Liu, Bernoco, & Turner, 1995;Mahi-Brown et al, 1985;Sacco, Pierce, Subramanian, Yurewicz, & Dukelow, 1987;Skinner, Mills, Kirchick, & Dunbar, 1984;Wood et al, 1981). Among horses, no abnormalities in ovarian histology were documented after 1 year of treatment with PZP (Liu, Bernoco, & Feldman, 1989); however, feral mares on PZP for 3 consecutive years demonstrated diminished urinary estrogen conjugate levels and lower ovulation rates than untreated mares (Kirkpatrick et al, 1992).…”

mentioning

confidence: 99%

“…In this study, estrous cycle characteristics were analyzed in a population of Assateague horses who were part of a long-term contraceptive field trial (Kirkpatrick et al, 1992(Kirkpatrick et al, , 1995. Young mares (age 2 years) are given two injections of PZP 2 to 4 weeks apart to begin contraception (Kirkpatrick et al, 1992).…”

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confidence: 99%

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Assessment: Effects of Porcine Zona Pellucida Immunocontraception on Estrous Cyclicity in Feral Horses

Powell¹,

Monfort²

2001

Journal of Applied Animal Welfare Science

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Section: Discussionmentioning

confidence: 91%

mentioning

confidence: 94%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Assessment: Effects of Porcine Zona Pellucida Immunocontraception on Estrous Cyclicity in Feral Horses

Powell¹,

Monfort²

2001

Journal of Applied Animal Welfare Science

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“…Claims have been made for the potential efficacy of immunocontraception for African elephants , Delsink et al 2002, although this view has been challenged on demographic grounds (Pimm & van Aarde 2001). Long-term studies on immunocontraception in wild horses report 78-94.2% contraceptive efficacy (Kirkpatrick et al 1995, Turner et al 1997, 2002, Turner & Kirkpatrick 2002.…”

Section: Variation In Response and Genetic Changementioning

confidence: 99%

Immunocontraception of mammalian wildlife: ecological and immunogenetic issues

Cooper

Larsen²

2006

Reproduction

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Immunocontraception involves stimulating immune responses against gametes or reproductive hormones thus preventing conception. The method is being developed for the humane control of pest and overabundant populations of mammalian wildlife. This paper examines three fundamental issues associated with its use: (1) the difficulties of obtaining responses to self-antigens, (2) the likely evolution of genetically based non-response to immunocontraceptive agents, and (3) the possible changes in the array of pathogens possessed by the target species after generations of immunocontraception. Our review of the literature demonstrates that the barriers to an effective immunocontraceptive are at present very basic. Should they be overcome, the effects of immunocontraception on the immunogenetic constitution of wildlife populations through the selection for nonresponders must be examined. We suggest that the attempt to use the animal's own immune system to modulate reproduction may be incompatible with the basic biological function of protection against infectious disease. Research programs on mammalian immunocontraception should involve measurement of the heritability of non-response and an assessment of the likely change in the response of the contracepted population to possible pathogens.

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

Ransom

Roelle

Cade

et al. 2011

Wildlife Society Bulletin

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Locally abundant feral horses (Equus caballus) can rapidly deplete available resources. Fertility control agents present promising nonlethal tools for reducing their population growth rates. We tested the effect of 2 forms of the immunocontraceptive porcine zona pellucida (PZP) on foaling rates in 3 populations of feral horses in the western United States. A liquid form requiring annual boosters was administered at Little Book Cliffs Wild Horse Range, Mesa County (CO), and Pryor Mountain Wild Horse Range, Bighorn County (WY) and Carbon County (MT), and a time-release pellet form designed to produce 2 yr of infertility was administered at McCullough Peaks Herd Management Area, Park County (WY). Average foaling rates (foals born/mare-yr) from direct observation of untreated and treated female horses (mares), 2004-2008, were 60.1% (n ¼ 153 mare-yr) versus 6.6% (n ¼ 91 mare-yr) at Little Book Cliffs, and 62.8% (n ¼ 129 mare-yr) versus 17.7% (n ¼ 79 mare-yr) at Pryor Mountain, respectively. At McCullough Peaks, mean annual foaling rates from 2006 to 2008 were 75.0% (n ¼ 48 mare-yr) for untreated mares and 31.7% (n ¼ 101 mare-yr) for treated mares.Controlling for age of mares and pretreatment differences in fertility, PZP reduced foaling rates in all 3 herds. The pellets used at McCullough Peaks (produced by cold evaporation) were less effective than pellets used in a previous trial and produced by heat extrusion. Immunocontraception with PZP may be a useful tool in reducing fertility rates in some western United States feral horse herds, but population growth reduction will depend on timely access to mares for inoculation and the proportion of mares that can be successfully treated. Published 2011. This article is a U.S. Government work and is in the public domain in the USA.

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Effects of Seven Consecutive Years of Porcine Zona Pellucida Contraception on Ovarian Function in Feral Mares1

Cited by 31 publications

References 22 publications

Assessment: Effects of Porcine Zona Pellucida Immunocontraception on Estrous Cyclicity in Feral Horses

Assessment: Effects of Porcine Zona Pellucida Immunocontraception on Estrous Cyclicity in Feral Horses

Immunocontraception of mammalian wildlife: ecological and immunogenetic issues

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

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