Effect of Vitamin E or Propolis Addition on Alleviation of Heat Stress Impact on Growing Rabbits

Abstract

his study was conducted to evaluate the effects of propolis (PS) or vitamin E (Vit. E) dietary supplementation on growth performance, nutrients digestibility, carcass characteristics and meat quality of growing New-Zeland White rabbits (NZW). Rabbits were reared in batteries and divided into five experimental groups (3 replicates in each treatment contain 10 NZW growing weaned rabbits in each replicate). The first group was fed a basal diet without any supplementation (control group). The second and third groups were fed basal diet supplemented with 100 and 150mg Vit. E/kg feed, while, the fourth and fifth groups supplemented with 100 and 150mg PS/kg feed, respectively. Rabbits were reared under heat stress condition (summer season in Egypt). Results showed that summer season had negative effects on all tested parameters. Supplementation of Vit. E or PS significantly increased final live body weight, total weight gain as well as improved, feed conversion rate, and performance index compared to the non-supplemented group (control group). There were no significant effects of rabbit diets supplemented with Vit. E or PS on crude fiber (CF) and nitrogen-free extract (NFE) digestibility, while all other nutrient digestibility and nutritive values were significantly increased. Rabbits fed diet supplemented with PS showed better growth performance and nutrient digestibility than those fed diet supplemented with Vit. E. The results clarified that, carcass and dressing percentages were significantly (P≤0.01) increased, also Heart, stomach and intestine percentages were significantly higher, while liver and lung percentages were not significantly affected in all experimental groups compared to the control group. Furthermore, the inclusion of Vit. E or PS on rabbit diets significantly reduced abdominal and shoulder fat percentages in all experimental groups compared to the control group. There was a significant increase in total protein content in meat with Vit. E or PS supplementation, this improvement is parallel to a significant decrease in total cholesterol, triglycerides and malondialdehyde (MDA). Furthermore, the percentages of drip loss and cook loss were significantly decreased in the supplemented groups compared with the control group. In conclusion, supplementing the NZW growing rabbit diets with Vit. E or PS allivated the harmful effects of heat stress on growth performance, nutrients digestibility, carcass characteristics and meat quality.