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Androgens, behaviour and fertility control in feral stallions.
Abstract: This field study of feral stallions in Montana and Idaho examines and correlates the seasonal pattern of plasma androgens and specific sociosexual behaviour and reports the effect of a long-acting androgenic steroid on this behaviour and on fertility. Plasma testosterone was measured by competitive protein binding assay in samples obtained by jugular venepuncture from captured animals. In samples taken from 34 sexually mature stallions in 6 different months during the year, a definite seasonal pattern in testosterone was present, with a peak in May (3.04 +/- 0.63 ng/ml) and a nadir in December (1.55 +/- 0.34 ng/ml). Values were less than 2.0 ng/ml in non-breeding months and greater than 2.4 ng/ml in breeding months. Behavioural endpoints measured were (1) stallion scent marking in response to elimination by mares (elimination marking), (2) mounting and (3) copulation. The frequencies of each of these endpoints followed closely the seasonal pattern seen for plasma androgens. In the fertility study microcapsulated testosterone propionate (microTP) was administered i.m. to 10 harem stud stallions 3 months before the 1980 breeding season. In these stallions and in 10 control harem studs, the above behavioural endpoints were examined in the 1980 and 1981 breeding seasons, and foal counts were made in 1981. There were no direct inhibitory or stimulatory effects of microTP treatment on any of the behavioural endpoints in either year. In 1981 foals were produced in 87.5% of the control bands and 28.4% of the microTP-treated bands. These results indicate that microencapsulated testosterone propionate can provide effective fertility control in feral horses without causing significant alterations in sociosexual behaviour.
Publication Date: 1982-01-01 PubMed ID: 6962905 The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study investigates the relationship between plasma androgens, social and sexual behavior, and fertility in wild stallions. It also looks at the effects of an androgenic steroid on these factors. The researchers found that testosterone levels fluctuated seasonally and that these fluctuations mirrored certain behaviors. Additionally, they found that the administered androgenic steroid effectively controlled fertility without significantly influencing the measured behaviors.
Understanding Seasonal Patterns of Hormones and Behaviour
- The researchers investigated the relationship between the hormone testosterone, specifically plasma androgens, and certain social and sexual behaviors in feral stallions. They noted a clear seasonal pattern in testosterone levels, peaking in May and reaching the lowest point in December.
- The behaviors observed included scent marking in response to mares’ elimination, mounting, and copulation. Parallel to the testosterone levels, these behaviors also followed a distinct seasonal pattern.
Effects of Testosterone Propionate on Behaviour and Fertility
- The study then focused on examining the effect of microencapsulated testosterone propionate (microTP) on the measured behaviors and fertility. MicroTP is a long-acting androgenic steroid that was administered to a group of harem stud stallions three months before the breeding season.
- There were no direct inhibitory or stimulating effects of microTP treatment on any of the observed behaviors. Consequently, this indicates that testosterone levels do not directly guide the studied behaviour, but both are part of a seasonal cycle.
- However, the application of microTP had a significant effect on fertility. In the following breeding season, foals were produced in 87.5% of the control groups, as compared to just 28.5% in the MicroTP-treated groups. Therefore, this suggests microTP can effectively control fertility in wild stallions without significantly changing their social and sexual behaviors.
Cite This Article
APA
Turner JW, Kirkpatrick JF.
(1982).
Androgens, behaviour and fertility control in feral stallions.
J Reprod Fertil Suppl, 32, 79-87.
Publication
Researcher Affiliations
MeSH Terms
- Animals
- Animals, Wild
- Copulation / drug effects
- Female
- Fertility / drug effects
- Horses / physiology
- Male
- Periodicity
- Pregnancy
- Seasons
- Sexual Behavior, Animal / drug effects
- Sexual Maturation
- Sperm Count
- Sperm Motility / drug effects
- Testosterone / blood
- Testosterone / pharmacology
Citations
This article has been cited 3 times.- Isaacs JT. Consequence of evolutionary loss of seasonal breeding by humans for prostate cancer chemoprevention. Am J Clin Exp Urol 2023;11(3):194-205.
- Tsuruta JK, Dayton PA, Gallippi CM, O'Rand MG, Streicker MA, Gessner RC, Gregory TS, Silva EJ, Hamil KG, Moser GJ, Sokal DC. Therapeutic ultrasound as a potential male contraceptive: power, frequency and temperature required to deplete rat testes of meiotic cells and epididymides of sperm determined using a commercially available system. Reprod Biol Endocrinol 2012 Jan 30;10:7.
- Kent MG, Schneller HE, Hegsted RL, Johnston SD, Wachtel SS. Concentration of serum testosterone in XY sex reversed horses. J Endocrinol Invest 1988 Sep;11(8):609-13.
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