Seasonal and circadian changes of testosterone levels in the peripheral blood plasma of stallions and their relation to semen quality

Byers, S. W.; Dowsett, K. F.; Glover, T. D.

doi:10.1677/joe.0.0990141

Cited by 17 publications

(3 citation statements)

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“…with lowest values during winter, as reported by others (Byers et al, 1983;Cox et al, 1988;Clay and Clay, 1992;Inoue et al, 1992;Aurich et al, 2003) was not seen in our study. A seasonal effect of testosterone was also absent after hCG-stimulation, performed in July, October and December.…”

Section: Discussionsupporting

confidence: 76%

Influence of long-term treatment with equine somato-tropin (EquiGen®) on gonadal function in stallions with poor semen quality

Botton¹,

Janett

Burger³

et al. 2008

Schweizer Archiv für Tierheilkunde

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Influence of long-term treatment with equine somatotropin (EquiGen) on gonadal function in stallions with poor semen quality AbstractThe aim of the present study was to investigate the spermatogenic and Leydig cell activity in stallions with impaired semen quality after treatment with equine somatotropin. Experiments were performed using 18 adult clinically healthy stallions with poor semen quality which did not pass breeding soundness evaluation. The animals were randomly divided into a treatment (n = 9) and a control (n = 9) group. Over a period of 90 days, nine stallions received a daily intramuscular injection of 10 mg recombinant equine somatotropin (EquiGen, BresaGen Limited, Adelaide, Australia) and 9 control animals were injected with the same amount of physiological saline solution. During and until 2 months after treatment, semen characteristics and daily sperm output as well as plasma testosterone concentrations were determined monthly in all stallions. In addition, testosterone concentration measurement after stimulation with hCG was performed in all animals immediately before and at the end of the treatment period as well as 2 months later. Our results demonstrate that equine somatotropin (EquiGen) given daily in a dose of 10 mg per animal during 90 days had no significant effect neither on plasma testosterone concentrations and hCG-induced testosterone release nor on semen quality parameters in adult stallions with poor semen characteristics. Influence SummaryThe aim of the present study was to investigate the spermatogenic and Leydig cell activity in stallions with impaired semen quality after treatment with equine somatotropin.Experiments were performed using 18 adult clinically healthy stallions with poor semen quality which did not pass breeding soundness evaluation. The animals were randomly divided into a treatment (n=9) and a control (n=9)

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Section: Discussionsupporting

confidence: 76%

Influence of long-term treatment with equine somato-tropin (EquiGen®) on gonadal function in stallions with poor semen quality

Botton¹,

Janett

Burger³

et al. 2008

Schweizer Archiv für Tierheilkunde

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“…Inter-and intra-assay coefficients of variation were 9 and 4-4% respectively, sensitivity was 1-2 ng/ml and NIH-FSH-S12 was used as the reference standard. Testosterone concentrations were measured by the radioimmunoassay described by Byers, Dowsett & Glover (1983). Inter-and intra-assay coefficients of variation were 5-7 and 4% respectively.…”

Section: Methodsmentioning

confidence: 99%

Effect of scrotal insulation on the pituitary--testicular axis of the ram

Byers¹,

Glover²

1984

Reproduction

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“…The horse is a long-day breeder and considering annual variation in semen quality allows to optimize reproductive efficiency of stallions [1,2]. Seasonal influences on endocrine testicular function [3][4][5] as well as on common semen characteristics of fresh and frozenthawed semen are well documented in the literature [6][7][8]. Regarding cold-stored semen, however, only limited information is available comparing the quality between February and November [9] or between spring and summer [10].…”

Section: Introductionmentioning

confidence: 99%

Seasonal changes of DNA fragmentation and quality of raw and cold-stored stallion spermatozoa

et al. 2017

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In this study annual fluctuations of DNA fragmentation and quality of cold-stored equine sperm were evaluated. Ejaculates were collected weekly during one year from 15 stallions. Ejaculate volume, sperm concentration and total sperm count were determined and semen was then extended and cold-stored for 48 h. Sperm motility was evaluated by CASA before and after 24 as well as 48 h of cold storage. In addition, the percentages of sperm with intact plasma membrane and acrosome (PMAI %) and with low intracellular Ca level were determined in cold-stored semen (24 h, 48 h). SCSA™ was performed to assess mean DFI, SD of DFI and % DFI in raw frozen-thawed as well as in extended sperm after 24 and 48 h of storage. The month of semen collection affected (P < 0.05) all parameters evaluated in raw semen and all criteria except progressive motility as well as rapid cells in semen stored for 24 and 48 h, respectively. Ejaculate volume was higher and sperm concentration lower in summer compared to winter and motility lower in July than in any other month of the year (P < 0.05). In semen processed in April and stored for 24 h the percentage of rapid cells was improved compared to January and after 48 h of storage progressive motility (%) was higher in January and October than in July (P < 0.05). After 24 h of cold storage PMAI % was higher in October than in January and after 48 h values were higher in September compared to January and February as well as from April to July (P < 0.05). Regarding sperm with low intracellular Ca level (%) after storage for 24 and 48 h, higher values were measured in winter and in October compared to April, June and July (P < 0.01). Seasonal changes in DNA fragmentation were most evident with respect to mean DFI. In raw frozen-thawed semen mean DFI was lower from August to November than in June and July (P < 0.001). Values were lower during winter compared to spring and early summer (P < 0.05) and lower in December than from April to September (P < 0.001). After 24 h of cold storage mean DFI was lower in September and October when compared to January, February, May, July and November (P < 0.05) and after 48 h storage mean DFI was reduced in spring and autumn compared to February, June and July (P < 0.05). In conclusion, a seasonal effect was evident on semen characteristics of raw and cold-stored sperm. Semen quality was impaired in midsummer when low sperm motility and viability were combined with an elevated DNA fragmentation and Ca level of sperm.

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Seasonal and circadian changes of testosterone levels in the peripheral blood plasma of stallions and their relation to semen quality

Cited by 17 publications

References 0 publications

Influence of long-term treatment with equine somato-tropin (EquiGen®) on gonadal function in stallions with poor semen quality

Influence of long-term treatment with equine somato-tropin (EquiGen®) on gonadal function in stallions with poor semen quality

Effect of scrotal insulation on the pituitary--testicular axis of the ram

Seasonal changes of DNA fragmentation and quality of raw and cold-stored stallion spermatozoa

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