Essential Oil Blend and Ascorbic Acid Supplementation Improves Performance, Semen Characteristics, Redox Balance, and Intestinal Integrity in Heat-Stressed Male Rabbits

This study aimed to investigate the effects of supplementing with an essential oil blend and ascorbic acid on performance, semen characteristics, antioxidant status, gut microbiota, immunity, and gene expression in heat-stressed male rabbits. One hundred and forty male New Zealand White rabbits, aged 6 months, were randomly distributed into four dietary groups: the control group receiving basal feed (CON), the group receiving an essential oil blend (EOB, 200 mg/kg), the group receiving ascorbic acid (ASA, 1000 mg/kg), and the group receiving an essential oil blend and ascorbic acid (MAO). The experimental period lasted for eight weeks. The MAO mixture supported rabbits’ tolerance to heat stress by enhancing stress markers, as demonstrated by decreased glucose and HSP70 and increased triiodothyronine (T3). In addition, increased body weight, carcass weight, and nutrient digestibility, but reduced mortality rate, were observed in rabbits fed the MAO mixture. Additionally, semen density and volume, as well as sperm progressive motility and normality, were enhanced in rabbits fed the MAO mixture. Furthermore, MAO mixture supplementation decreases plasma cholesterol, triglycerides, AST, urea, and creatinine levels, while raising HDL and total protein levels. Adding MAO mixture contributed to an increase in plasma SOD and GPx levels, as well as seminal fluid TAC and GSH levels. Additionally, the incorporation of MAO increases IgA, IgG, and IL-10 levels while decreasing IL-6 and TNF-α levels. Adding the MAO mixture reduced C. perfringens and E. coli, as well as increased the expression of the MUC-2, CAT-1, and CLDN-1 genes. Combining an essential oil blend and ascorbic acid may contribute to improvements in performance, semen quality, immune response, antioxidant capacity, and gut health in heat-stressed male rabbits.