Seasonal Variation of Melatonin Concentration and mRNA Expression of Melatonin-Related Genes in Developing Ovarian Follicles of Mares Kept under Natural Photoperiods in the Southern Hemisphere

南半球自然光周期下母马发育卵泡中褪黑激素浓度及褪黑激素相关基因mRNA表达的季节性变化