The protective effect of aqueous orange peel extract against severe heat stress on reproductive efficiency, milk yield, and antioxidant status of female rabbits

Heat stress in rabbits negatively affects their reproductive ability and milk yield. Aqueous orange peel extract (AOPE) is high in potential natural antioxidants that help avoid free radical damage and is a good source of phytochemicals. Based on these benefits, it was hypothesized that oral administration of AOPE could overcome the negative impacts of severe heat stress on reproductive and lactation performance, physiological parameters, and antioxidant status. To determine the protective effect of AOPE, 36 female rabbits (six-months-old, average body weight of 2.67 ± 0.03 kg) were given 1.50 mL water (control), and 2.50 or 5.00 mL AOPE every two days for four months. Oral AOPE administration significantly reduced the respiration rate (RR) and rectal temperature (RT) during pregnancy and lactation. The reproductive performance (litter size) and productive performance (litter weight and litter weight gain) were significantly increased by AOPE treatment, compared with the control. The highest milk yield was recorded in 5.00 mL AOPE treatment (5.00 mL). AOPE treatments significantly increased serum superoxide dismutase (SOD) and catalase (CAT), and AOPE treatment (5.00 mL) lowered serum thiobarbituric acid reactive substances (TBARs) of heat-stressed rabbits. Serum total antioxidant capacity (TAC) was not affected by AOPE treatment. The addition of AOPE improved reproductive performance, physiological parameters, and antioxidant status, but did not have a beneficial effect on conception rate of female rabbits under severe heat stress.