Effects of Dietary Supplementations of Vitamin C, Organic Selenium, Betaine, and Pomegranate Peel on Alleviating the Effect of Heat Stress on Growing Rabbits

: The aim of this study was to investigate the biological activity and sustainable biorefinery development of vitamin C, organic selenium, betaine, and pomegranate peel on the performance, cecal fermentation, and antioxidant status of growing rabbits to alleviate the negative impacts of heat stress. A total of 105 male rabbits at 35 days old with an average weight of 752.55 ± 27.56 g were randomly assigned to five groups (21 rabbits in each). The experimental dietary groups included a control group fed a basal diet without additives (control group) and four treated groups, A, B, C, and D, fed a basal diet supplemented with either a 1000 mg vitamin C/kg diet, a 25 mg organic selenium/kg diet, a 1000 mg betaine/kg diet, or a 20 g pomegranate peel/kg diet, respectively. No negative group (not heat-stressed) was included in the trial. Rabbits given A, B, C, and D supplements showed a significant increase (p < 0.05) in growth performance, nutrient digestion, concentration of total volatile fatty acids (VFA), acetic, and propionic acids, and total bacterial count, and a significant decrease (p < 0.05) in NH3-N concentration, Enterococcus, coliforms, and E. coli counts in the cecum of rabbits. Total protein, albumin, globulin, superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), and glutathione peroxidase (GPx) were significantly (p < 0.05) higher in groups supplemented with A, B, C, and D supplements compared to those in the control group. Total cholesterol, triglycerides, creatinine, urea, and malondialdehyde (MDA) were significantly (p < 0.05) lower in groups supplemented with A, B, C, and D supplements compared to those in the control group. In conclusion, the finding showed that the supplementation of vitamin C, organic selenium, betaine, and pomegranate peel played a significant role in alleviating heat stress and had a further beneficial impact on rabbit performance, cecal fermentation and microbiota, and antioxidant status. However, betaine supplementation had a superior positive effect on the nutritional and physiological profile of heat-stressed rabbits.