Testosterone serum profile, semen characteristics and testicular biometry of Mangalarga Marchador stallions in a tropical environment

Abstract

This study was conducted to characterize the daily profile of testosterone secretion and its mean concentrations in the four seasons as well as to evaluate the semen characteristics and testicular biometry of Mangalarga Marchador stallions throughout the year in a tropical region. Three stallions were submitted to semen collections and evaluation of testicular biometry every 14 days along a year. Blood samples were collected once at the middle of each season, in a 20-min interval during 24 hr in order to evaluate the testosterone secretion profiles among seasons. Testosterone concentrations along the day were higher at the beginning of the afternoon (from 12:00 to 15:00 hr), but a circadian secretion was not clearly observed. Mean testosterone concentrations did not differ among seasons (p > .05), but a pattern of secretion along the day showed variations with higher concentrations in the afternoon during the winter. Ejaculate volume was higher during summer; however, sperm motility decreased in summer and spring. Total sperm in ejaculate, sperm morphology and testicular biometry kept constant along the year showing no differences among the seasons. The results demonstrated that in a tropical region, reproductive aspects of stallions did not show a clearly defined seasonal variation, and months of autumn and winter were not unsuitable for reproduction of the males.

Body and testicular biometry of Crioulo stallions

“…Data regarding testicular biometry are shown in table 2. Among the parameters evaluated, there was no significant difference between the linear measurements of right and left testicles, similar to that described in the literature by GREGORY (2013) and MENDES (2012) in Crioulo horses; by BORGES et al (2010), PARLEVLIET et al (1994 and WADDINGTON et al, (2017) in other breeds. Testicular height, length, width and volume showed a positive correlation between ipsi and contralateral testis, testicular volume and DSO.…”

“…Considering other breeds, values of testicular biometry of Crioulo stallions are lower than those reported for Campolina (BORGES et al, 2010;MANSO FILHO et al, 2000) and Mangalarga Marchador (CRUZ et al, 2009;WADDINGTON et al, 2017). The Crioulo breed is considered small to medium sized, while the other reported breeds are considered medium to large sized.…”

Monthly Evaluation of Testicular Biometry and Sexual Behavior With Respect to Seminal Aspects of Arabian Stallions Under Subtropical Conditions in Kuwait

“…Testicle biometry was evaluated twice monthly (every 14 days) throughout one year (December 2019 to November 2020). Length (distance between cranial and caudal pole), width (distance between the lateral and the medial side), height (distance between the dorsal and the ventral surfaces) were recorded using digital caliper for each testis and testicular volume (width x height x length x 0.5333) was recorded according to (Love et al, 1991;Waddington et al, 2017). Thickness of scrotal skin (TS) was recorded using digital caliper and width of total scrotum (WTS; the width across both testes together) was recorded using plastic meter according to (Thompson et al, 1979;Clay et al, 1987).…”

Hair Cortisol, Testosterone, Dehydroepiandrosterone Sulfate and Their Ratios in Stallions as a Retrospective Measure of Hypothalamic–Pituitary–Adrenal and Hypothalamic–Pituitary–Gonadal Axes Activity: Exploring the Influence of Seasonality

“…Previous studies have examined hair cortisol concentrations (HCC) as a presumptive measure of stress, and demonstrated their seasonal fluctuations in horses [ 18 , 22 , 27 , 28 ]. Few studies have been performed using T [ 11 , 28 , 29 , 30 ] and, to date, to the best of our knowledge, there is no information published on the seasonal variations in the hair T levels of horses. Although the C/DHEA ratio has been previously described in horse’s hair to evaluate the effect of different housing conditions [ 8 ], there is still a lack of information on its biological relevance in the horse.…”