Effects of dietary thymoquinone inclusion on antioxidative, oxidative, pro-inflammatory responses, semen attributes and testicular changes in heat-stressed rabbit bucks

Abstract Heat stress (HS) is considered a severe concern for rabbit buck’s health, welfare and reproductive features. Thymoquinone (THQ) is a natural molecule with robust antioxidant, antimicrobial, and anti-inflammatory properties. Thereafter, three months of feeding research was applied to assess the role of THQ-enriched diets in improving the health, semen attributes and testicular changes of stressed rabbit bucks. Forty rabbit bucks were used in this research, and animals were fed diets containing 0 (THQ0; serve as a heat stress group), 100 (THQ100), 200 (THQ200), and 400 (THQ400) mg/kg of THQ for three months continually during the summer season. Outcomes displayed that THQ significantly enhanced FBW (final body weight), DBWG (daily body weight gain), and FI (feed intake) but did not affect FCR (feed conversion ratio). Compared with the THQ0 group, dietary THQ addition significantly decreased creatinine, TB (total bilirubin), TG (triglycerides), and GGT (gamma-glutamyl transferase) levels. Bucks receiving 200 mg of THQ had higher TAC (total antioxidant capacity) and GSH (glutathione) than other groups. At the same time, MDA was significantly shrunk in THQ-treated groups relative to the THQ group. The levels of interferon-gamma (IFN-ᵞ) and interleukin-4 (IL-4) were significantly diminished (P <0.001), but nitric oxide and lysosome activity were significantly increased in bucks given diets containing THQ (200 and 400 mg/kg) as relative to the TH0 group. Libido score and reaction time were significantly improved by THQ dietary inclusion. Semen attributes, including volume, motility, concentration, and vitality, were significantly augmented in THQ100 and THQ200 groups. Histological screening of testicular tissues showed moderate to severe degenerative and necrotic changes in the testicular tissues of bucks exposed to HS. This was enhanced with the supplementation of THQ at different levels. Collectively, THQ (200 or 400mg /kg diet) can improve health, semen attributes and restore testicular damage in rabbit bucks via boosting antioxidant and reducing inflammatory cytokines.