N‐Acetylcysteine Supplementation Improves Testicular Haemodynamics, Testosterone Levels, Seminal Antioxidant Capacity and Semen Quality in Heat‐Stressed Goat Bucks

ABSTRACT Heat stress (HS) disrupts testicular homeostasis because of oxidative stress. N‐acetylcysteine (NAC) is a thiol compound with antioxidants, anti‐inflammatory and anti‐apoptotic properties. As a sequel, this research aimed to assess the ameliorative effects of NAC supplementation on the reproductive performance of goat bucks kept under environmental HS. Primarily, Doppler examination as well as semen collection and evaluation were conducted on 12 mature bucks for 2 weeks (W) as pre‐heat stress control (W1 and W2) during winter (February 2023). The temperature–humidity index (THI) was 63.4–64.3 (winter season). Then during summer HS conditions (from the beginning of July till the end of August 2023) bucks were assessed before NAC supplementation (W0), afterwards they were arbitrarily assigned into two groups. The control group (CON; n = 6) received the basal diet while the NAC group (n = 6) received the basal diet in addition to oral NAC daily for 7 weeks (W1–W7). The THI was 78.1–81.6 (summer season). Testicular blood flow parameters, serum concentration of nitric oxide (NO) and testosterone were measured. Additionally, total antioxidant capacity (TAC) and malondialdehyde (MDA) content in seminal plasma and semen quality parameters were evaluated. There were marked reductions (p