{"id":9776,"date":"2025-08-10T20:16:17","date_gmt":"2025-08-10T20:16:17","guid":{"rendered":"http:\/\/drmhasghari.com\/serum-testosterone-in-arabian-stallions-during-breeding-and-non-breeding-seasons-in-iran\/"},"modified":"2026-08-05T16:18:28","modified_gmt":"2026-08-05T16:18:28","slug":"serum-testosterone-in-arabian-stallions-during-breeding-and-non-breeding-seasons-in-iran","status":"publish","type":"post","link":"https:\/\/drmhasghari.com\/en\/serum-testosterone-in-arabian-stallions-during-breeding-and-non-breeding-seasons-in-iran\/","title":{"rendered":"Serum testosterone in Arabian stallions during breeding and non-breeding seasons in Iran"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_85 ez-toc-wrap-center counter-hierarchy ez-toc-counter-rtl ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #62c0e0;color:#62c0e0\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #62c0e0;color:#62c0e0\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 eztoc-toggle-hide-by-default' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/drmhasghari.com\/en\/serum-testosterone-in-arabian-stallions-during-breeding-and-non-breeding-seasons-in-iran\/#Introduction\" >Introduction<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/drmhasghari.com\/en\/serum-testosterone-in-arabian-stallions-during-breeding-and-non-breeding-seasons-in-iran\/#Materials_and_Methods\" >Materials and Methods<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/drmhasghari.com\/en\/serum-testosterone-in-arabian-stallions-during-breeding-and-non-breeding-seasons-in-iran\/#Study_Area_and_Climatic_Conditions\" >Study Area and Climatic Conditions<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/drmhasghari.com\/en\/serum-testosterone-in-arabian-stallions-during-breeding-and-non-breeding-seasons-in-iran\/#Animals_Under_Study\" >Animals Under Study<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/drmhasghari.com\/en\/serum-testosterone-in-arabian-stallions-during-breeding-and-non-breeding-seasons-in-iran\/#Sampling_Schedule\" >Sampling Schedule<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/drmhasghari.com\/en\/serum-testosterone-in-arabian-stallions-during-breeding-and-non-breeding-seasons-in-iran\/#Sample_Collection_and_Hormonal_Analysis\" >Sample Collection and Hormonal Analysis<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/drmhasghari.com\/en\/serum-testosterone-in-arabian-stallions-during-breeding-and-non-breeding-seasons-in-iran\/#Statistical_Analysis\" >Statistical Analysis<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/drmhasghari.com\/en\/serum-testosterone-in-arabian-stallions-during-breeding-and-non-breeding-seasons-in-iran\/#Results\" >Results<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/drmhasghari.com\/en\/serum-testosterone-in-arabian-stallions-during-breeding-and-non-breeding-seasons-in-iran\/#Discussion\" >Discussion<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/drmhasghari.com\/en\/serum-testosterone-in-arabian-stallions-during-breeding-and-non-breeding-seasons-in-iran\/#Conclusion\" >Conclusion<\/a><\/li><\/ul><\/nav><\/div>\n<h2 style=\"direction: ltr;\" data-start=\"231\" data-end=\"241\"><span class=\"ez-toc-section\" id=\"Introduction\"><\/span>Introduction<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"direction: ltr;\"><span style=\"font-size: 16px;\">The horse is a seasonal polyestrous species associated with increase in day light (Guillaume, \u06f1\u06f9\u06f9\u06f6; Nagy et al., \u06f2\u06f0\u06f0\u06f0) temperature and availability of food (Nagy et al., \u06f2\u06f0\u06f0\u06f0). Long day period increases the mean LH and T\u06f2 levels in pony stallions and the onset of the ovulatory season in pony mares (Berndtson et al., \u06f1\u06f9\u06f8\u06f3).<\/span><\/p>\n<p style=\"direction: ltr;\"><span style=\"font-size: 16px;\">In the Northern Hemisphere, the natural breeding season of horses usually extends from April to September. Previous studies have shown that seasonal changes in day length have a direct effect on fertility and semen quality in stallions. However, limited information has been available regarding the seasonal variations in testosterone concentration in Arabian stallions of Khuzestan Province (with its specific climatic conditions and different day lengths). This study was conducted to investigate these variations under natural light conditions.<\/span><\/p>\n<h2 style=\"direction: ltr;\" data-start=\"941\" data-end=\"959\"><span class=\"ez-toc-section\" id=\"Materials_and_Methods\"><\/span>Materials and Methods<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3 style=\"direction: ltr;\" data-start=\"961\" data-end=\"992\"><span class=\"ez-toc-section\" id=\"Study_Area_and_Climatic_Conditions\"><\/span>Study Area and Climatic Conditions<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"direction: ltr;\" data-start=\"993\" data-end=\"1215\">The study was conducted in Khuzestan Province, Ahvaz City (latitude \u06f4\u06f8\u00b0\u06f4\u06f0\u2032N, longitude \u06f3\u06f1\u00b0\u06f2\u06f0\u2032E, elevation \u06f2\u06f2.\u06f5 m above sea level). The region has an average annual rainfall of \u06f1\u06f5.\u06f4\u06f8 mm and a temperature range between \u06f1\u00b0C and \u06f5\u06f0\u00b0C.<\/p>\n<h3 style=\"direction: ltr;\" data-start=\"1217\" data-end=\"1242\"><span class=\"ez-toc-section\" id=\"Animals_Under_Study\"><\/span>Animals Under Study<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"direction: ltr;\" data-start=\"1243\" data-end=\"1412\">In this study, \u06f2\u06f3 healthy Arabian stallions, aged \u06f3 to \u06f1\u06f5 years and weighing between \u06f4\u06f5\u06f0 and \u06f6\u06f0\u06f0 kg, were examined. All horses were fed a standard diet and housed in stables.<\/p>\n<h3 style=\"direction: ltr;\" data-start=\"1414\" data-end=\"1440\"><span class=\"ez-toc-section\" id=\"Sampling_Schedule\"><\/span>Sampling Schedule<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"direction: ltr;\" data-start=\"1441\" data-end=\"1513\">To investigate the effect of seasonal changes, blood sampling was carried out during two periods:<\/p>\n<ul data-start=\"1514\" data-end=\"1680\">\n<li data-start=\"1514\" data-end=\"1592\">\n<p style=\"direction: ltr;\" data-start=\"1516\" data-end=\"1592\"><strong data-start=\"1516\" data-end=\"1533\">Breeding Season:<\/strong> May to June (Summer Solstice; day length \u06f1\u06f4 hours and \u06f1\u06f1 minutes)<\/p>\n<\/li>\n<li data-start=\"1593\" data-end=\"1680\">\n<p style=\"direction: ltr;\" data-start=\"1595\" data-end=\"1680\"><strong data-start=\"1595\" data-end=\"1616\">Non-Breeding Season:<\/strong> November to December (Winter Solstice; day length \u06f1\u06f0 hours and \u06f2\u06f6 minutes)<\/p>\n<\/li>\n<\/ul>\n<h3 style=\"direction: ltr;\" data-start=\"1682\" data-end=\"1723\"><span class=\"ez-toc-section\" id=\"Sample_Collection_and_Hormonal_Analysis\"><\/span>Sample Collection and Hormonal Analysis<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"direction: ltr;\" data-start=\"1724\" data-end=\"1999\">From each stallion, \u06f1\u06f0 mL of blood was collected from the jugular vein. After centrifugation, the serum was stored at \u2212\u06f2\u06f0\u00b0C. Testosterone concentration was measured using a radioimmunoassay (RIA) kit with a minimum sensitivity of \u06f0.\u06f0\u06f5 ng\/mL. All samples were analyzed in duplicate within a single assay run.<\/p>\n<h3 style=\"direction: ltr;\" data-start=\"2001\" data-end=\"2018\"><span class=\"ez-toc-section\" id=\"Statistical_Analysis\"><\/span>Statistical Analysis<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"direction: ltr;\" data-start=\"2019\" data-end=\"2164\">Comparison of mean testosterone concentrations between the two seasons was performed using a paired t-test. Environmental temperature, relative humidity, and sunlight duration data were also compared between the two seasons.<\/p>\n<h2 style=\"direction: ltr;\" data-start=\"2171\" data-end=\"2181\"><span class=\"ez-toc-section\" id=\"Results\"><\/span>Results<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"direction: ltr;\" data-start=\"2182\" data-end=\"2377\">Climatic data showed that day length was significantly longer in summer compared to winter &lt; and ambient temperature was also higher in summer (\u06f3\u06f8.\u06f4\u00b0C vs. \u06f9.\u06f7\u00b0C).<\/p>\n<p style=\"direction: ltr;\" data-start=\"2379\" data-end=\"2557\">The mean serum testosterone concentration during the breeding season was <strong data-start=\"2423\" data-end=\"2457\">\u06f1.\u06f0\u06f8 \u00b1 \u06f0.\u06f0\u06f7\u06f8 ng\/mL<\/strong>, whereas in the non-breeding season it was <strong data-start=\"2480\" data-end=\"2513\">\u06f0.\u06f6\u06f5 \u00b1 \u06f0.\u06f1\u06f1 ng\/mL<\/strong>, showing a significant difference (&lt;).<\/p>\n<h2 style=\"direction: ltr;\" data-start=\"2564\" data-end=\"2572\"><span class=\"ez-toc-section\" id=\"Discussion\"><\/span>Discussion<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"direction: ltr;\" data-start=\"2573\" data-end=\"2848\">The results of this study confirm the presence of a seasonal rhythm in the reproductive cycle of Arabian stallions in Khuzestan. This pattern is consistent with previous findings in other horse breeds and ponies in the Northern Hemisphere, which reported the highest testosterone concentrations during the breeding season and the lowest levels in winter.<\/p>\n<p style=\"direction: ltr;\" data-start=\"2850\" data-end=\"3113\">The role of photoperiod (day length) is central to these changes; light is transmitted through the retina to the pineal gland, leading to a reduction in melatonin secretion. The decrease in melatonin stimulates the release of GnRH, which in turn increases LH secretion and ultimately stimulates Leydig cells in the testes to produce testosterone.<\/p>\n<p style=\"direction: ltr;\" data-start=\"3115\" data-end=\"3293\">Interestingly, the extremely high summer temperatures in Khuzestan did not have a significant negative effect on testosterone secretion, indicating the physiological adaptability of Arabian stallions in this region to hot climatic conditions.<\/p>\n<h2 style=\"direction: ltr;\" data-start=\"3300\" data-end=\"3315\"><span class=\"ez-toc-section\" id=\"Conclusion\"><\/span>Conclusion<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<ul>\n<li style=\"direction: ltr;\" data-start=\"3318\" data-end=\"3417\">Testosterone concentrations in Arabian stallions are significantly higher during the breeding season compared to the non-breeding season.<\/li>\n<li style=\"direction: ltr;\" data-start=\"3420\" data-end=\"3484\">Day length is considered the main factor regulating the hormonal cycle in this breed.<\/li>\n<li style=\"direction: ltr;\" data-start=\"3487\" data-end=\"3561\">The hot climatic conditions of Khuzestan do not have a significant negative effect on testosterone secretion.<\/li>\n<\/ul>\n<blockquote>\n<p style=\"direction: ltr;\"><strong>Download Link: <a href=\"https:\/\/academicjournals.org\/journal\/AJB\/article-full-text-pdf\/AE1254639094\" target=\"_blank\" rel=\"noopener\">Serum testosterone in Arabian stallions during breeding and non-breeding seasons in Iran | October \u06f1\u06f2, \u06f2\u06f0\u06f1\u06f1<\/a><\/strong><\/p>\n<\/blockquote>\n<p style=\"direction: ltr;\">\n","protected":false},"excerpt":{"rendered":"<p>Investigation of Testosterone Concentration Changes in Arabian Stallions of Khuzestan Province During Breeding and Non-Breeding Seasons and the Role of Day Length in Regulating the Reproductive 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