Ovarian follicle number (A) and weight (B) in the control and heat challenge group. Egg weight in the control and heat challenge group (C). Representative photo of an ovary of control (D, left) and heat group (D, right). Hierarchical follicle (HF), small yellow follicle (SYF), large white follicle (LWF). F1, F2, F3 indicate hierarchical follicles (F1 > F2 > F3), bar = 1 cm. Each bar represents the mean ± SEM. ∗Significantly different from the values at control (P < 0.05, T test). ∗∗Significantly different from the values at control (P < 0.01, T test). N.S. means no significant difference (P > 0.05, T test).