Repeated Melatonin Implant Improves Testicular Volume, Testicular Blood Flow, Estradiol, Antioxidant Capacity, and Nitric Oxide Levels in Post‐Pubertal Camels Under Heat Stress Conditions

This current work aimed to determine the impacts of melatonin implants on testicular artery blood flow and Doppler indices, in relation to hormonal profile in post-pubertal camels (Camelus dromedaries) under heat stress and non-breeding conditions. Post-pubertal males were categorised into control (C; n = 7) and melatonin-treated group (MT; n = 7; two doses 1 month apart starting in June). Testicular morphometric expressed by testicular volume and testicular echogenicity (TV and TE), Doppler indices as resistance index and pulsatility index (RI and PI) of testicular artery (TA), testicular blood flow volume (TBFV), blood sampling and hormonal (melatonin, follicle stimulating, luteinizing hormone [FSH and LH], estradiol [E2], testosterone [T], and nitric oxide [NO]) analysis and total antioxidant capacity (TAC) measurement were performed weekly. TV was elevated (p ≤ 0.05) in the MT group, reaching a peak at week 12, compared to C males, while TE did not change (p ≥ 0.05) due to melatonin implants. Melatonin, E2, and NO were increased significantly (p ≤ 0.05) from week 2, reaching the peak at wks. 7 and 8 of the implant. In addition, TAC showed the same pattern of elevation (p ≤ 0.05). FSH, LH, and T levels showed non-significant alterations (p ≥ 0.05). TA. RI and TA. PI declined from week 4 with an elevation (p ≤ 0.05) in TBFV. Melatonin implant improves the testicular vascularization with an elevation of the vasodilator mechanism. This led to a perfect breeding period in camels following the long photoperiod that extended the breeding period by 2-3 months.