Testicular growth, hormone concentrations, seminal characteristics and sexual behaviour in stallions.
Abstract: Puberty was studied using 15 colts of Quarter Horse phenotype. Total scrotal width was measured every 8 weeks from 48 to 96 weeks. Blood samples were taken from 8 colts at 8, 16 and 24 weeks and then every 4 weeks until 100 weeks to measure changes in LH, FSH and testosterone concentrations. Seminal collections were attempted monthly from 48 to 64 weeks and every 2 weeks thereafter until puberty resumed every 3rd day from 96 weeks for 15 ejaculates. For all collections, times to erection, mount and ejaculation and seminal characteristics were recorded. Age at puberty was defined as the first ejaculate containing 50 x 10(6) spermatozoa, with greater than or equal to 10% motile. Colts were castrated at 2 years to enable determination of daily sperm production (DSP), epididymal sperm reserves and normality of spermatogenesis. Total scrotal width increased linearly from 48 to 96 weeks. Age at puberty averaged 83 weeks (56-97 weeks). Changes in serum concentrations of LH and FSH were parallel, rising at 36-40 weeks, declining after 40 weeks and rising again at 68-80 weeks. Testosterone was low until 68 weeks after which concentrations rose slowly to 80 weeks and increased rapidly to a plateau at 92 weeks. Sexual behaviour and seminal characteristics differed (P less than 0.05) between puberty and 2 years, except for time to erection, time to mount, and percentage of motile spermatozoa. DSP at 2 years averaged 1.7 x 10(9) and daily sperm output (DSO) averaged 1.1 x 10(9). The correlation between DSP and DSO was 0.83 (P less than 0.01). There were 9.57 x 10(9) spermatozoa/epididymis of which 67% were in the cauda.
Publication Date: 1990-01-01 PubMed ID: 2107299DOI: 10.1530/jrf.0.0880167Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article primarily investigates puberty in Quarter Horse phenotype stallions, focusing on testicular growth, hormone concentrations, seminal features, and sexual behaviour. It also establishes a definition for the onset of puberty in these colts, marked by the presence of specific spermatological attributes in their first ejaculation.
Study Methodology
- The researchers used a group of 15 Quarter Horse-type colts and monitored their biological and sexual development over a period of 48 to 100 weeks.
- Scrotal width measurements and blood samples were taken at regular intervals. The blood samples were tested for concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone.
- Regular semen collections were started from 48 to 64 weeks, followed by detailed ejaculate analysis, primarily looking at the presence of spermatozoa and its motility levels, and recorded times to erection, mount, and ejaculation.
Main Findings
- The study found that testicular growth, as indicated by total scrotal width, followed a linear path from 48 to 96 weeks.
- Puberty onset in these colts was marked by the first ejaculate that contained 50 million spermatozoa with at least 10% motility. This event, on average, occurred at around 83 weeks of age but ranged from 56 to 97 weeks.
- There was a notable parallel in the rise and fall of LH and FSH serum concentrations, with peaks observed at 36-40 weeks and 68-80 weeks, while testosterone levels remained low until 68 weeks and increased steadily thereafter.
- Sexual behaviour and seminal attributes demonstrated significant variations between puberty and two-year intervals, with exceptions found for time to erection, time to mount, and the percentage of motile spermatozoa.
- The daily sperm output (DSO) showed a correlation of 0.83 with daily sperm production (DSP), suggesting a strong relationship between the two factors.
- The study concludes mentioning the spermatozoa count in the epididymis and their distribution, with the majority (67%) located in the cauda, the tail end of the epididymis.
Cite This Article
APA
Naden J, Amann RP, Squires EL.
(1990).
Testicular growth, hormone concentrations, seminal characteristics and sexual behaviour in stallions.
J Reprod Fertil, 88(1), 167-176.
https://doi.org/10.1530/jrf.0.0880167 Publication
Researcher Affiliations
- Animal Reproduction Laboratory, Colorado State University, Fort Collins 80523.
MeSH Terms
- Animals
- Follicle Stimulating Hormone / blood
- Gonadotropins, Pituitary / blood
- Horses / physiology
- Luteinizing Hormone / blood
- Male
- Semen / physiology
- Sertoli Cells / physiology
- Sexual Behavior, Animal / physiology
- Sexual Maturation / physiology
- Sperm Count
- Spermatozoa / cytology
- Testis / growth & development
- Testosterone / blood
Citations
This article has been cited 6 times.- Huijsmans TERG, Hassan HA, Smits K, Van Soom A. Postmortem Collection of Gametes for the Conservation of Endangered Mammals: A Review of the Current State-of-the-Art. Animals (Basel) 2023 Apr 15;13(8).
- Li B, He X, Zhao Y, Bai D, Bou G, Zhang X, Su S, Dao L, Liu R, Wang Y, Manglai D. Identification of piRNAs and piRNA clusters in the testes of the Mongolian horse. Sci Rep 2019 Mar 22;9(1):5022.
- Yoon M, Jiang J, Chung KH, Roser JF. Immunolocalization of insulin-like growth factor-I (IGF-I) and its receptors (IGF-IR) in the equine epididymis. J Reprod Dev 2015;61(1):30-4.
- Lejeune JP, Franck T, Gangl M, Schneider N, Michaux C, Deby-Dupont G, Serteyn D. Plasma concentration of insulin-like growth factor I (IGF-I) in growing Ardenner horses suffering from juvenile digital degenerative osteoarthropathy. Vet Res Commun 2007 Feb;31(2):185-95.
- Koskinen E, Andersson M, Katila T. Effect of 19-norandrostenololylaurate on testicular growth in colts. Acta Vet Scand 1997;38(1):51-7.
- Holyoak GR, Little TV, McCollam WH, Timoney PJ. Relationship between onset of puberty and establishment of persistent infection with equine arteritis virus in the experimentally infected colt. J Comp Pathol 1993 Jul;109(1):29-46.
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