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Abstract The present study was carried out at Rabbit Research Unit and Poultry Physiology Laboratory, Poultry Production Department, Faculty of Agriculture, Ain Shams University and Animal Production Department, National Research Centre, during the period from January to May 2014. The present study was designed to evaluate the effect of some natural additives, such as moringa dry leaves and rosemary dry leaves, on body weight gain, nutrients digestibility, dietary nitrogen utilization, hematological and blood biochemical profile, antimicrobial potentiality and histological changes of growing rabbits reared under artificial heat stress conditions. Sixty three male growing New Zealand White rabbits (NZW) aged six weeks old with an average body weight of 750.0±5.8g were distributed by weight in seven equal groups. The first group was of control group, the second and third groups were fed diets supplied by moringa dry leaves powder (0.5% and 1.0%, respectively), the fourth and fifth groups were fed diets supplied by rosemary dry leaves powder (0.5% and 1.0%, respectively), the sixth group was fed the basal diet supplemented with 0.25% moringa dry leaves powder+0.25% rosemary dry leaves powder, while the seventh group fed the basal diet supplemented with 0.5% moringa dry leaves powder+0.5% rosemary dry leaves powder. Feed was offered ad-libtum and water was free choice during the experimental period which lasted 9 weeks. Electrical heaters have been used to control the temperature inside the station at 33.1±0.5°C, and the level of relative humidity at 43±3%. Data were collected to determine the effect of different treatments on live body weight, weight gain, feed consumption and feed conversion. At the end of feeding experiment, three animals from each group have been slaughtered to collect blood samples for determine carcass characteristics, hematology profile, blood constituents and histological changes of liver, jejunum and cecum. Also, intestinal and cecal content samples have been collected to evaluate intestinal microbial potentiality.The results obtained can be summarized as follows: 1. Live body weight and body weight gain of rabbits did not significantly influenced among experimental groups. 2. Feed consumption and feed conversion ratio were numerically improved in all treatment groups compared with control group, where the best values were recorded for mixture 0.5% moringa+0.5% rosemary group followed by 0.5% moringa group. 3. Water consumption has not affected among experimental groups. 4. Carcass characteristic traits were not affected in treated rabbits. 5. Nutrients digestibility coefficients and nutritive values of the experimental diets were not affected with different dietary treatments. 6. Nitrogen balance was significantly increased among experimental groups, where the best value was recorded for 1% moringa group. 7. Hemoglobin levels were significantly increased among experimental groups, where the best values were established for groups fed high and low mixtures of moringa and rosemary, respectively. 8. Different dietary supplementations did not affect plasma glucose, total protein, albumin and globulin. 9. Plasma total lipids of growing rabbits were significantly decreased in all treatment groups compared by the control one, where the lowest value obtained was recorded for group fed mixture 0.25% moringa+ 0.25% rosemary. 10. There were significant decreases in plasma cholesterols and low density lipoprotein levels of growing rabbits which fed different supplements compared with the control one. 11. Moringa supplementation to growing rabbit’s diets numerically increased tri-iodothyronine (T3) levels. 12. Plasma corticosterone levels were significantly decreased among experimental groups, where the lowest values were recorded for groups fed 0.5% moringa.13. Liver enzyme activity (AST) was significantly decreased by dietary supplementation with mixture of 0.25% moringa + 0.25% rosemary. 14. Hemolysatic malondialdehyde level was significantly decreased among experimental groups, where the lowest value was recorded for group fed mixture of 0.25% moringa + 0.25% rosemary. 15. Hemolysatic total antioxidant capacity significantly increased among experimental groups, where the highest value was recorded for group fed on diets supplied with 0.5% rosemary. 16. Catalase, glutathione peroxidase and superoxide dismutase activities were significantly increased among experimental groups compared with control one. 17. Intestinal and cecal bacteria enumeration significantly decreased among experimental groups compared with control group. 18. Dietary treatments increased the number and size of intestinal villi, crypts of Lieberkühn and Brunner’s glands. The best observations are in moringa (0.5% and 1.0%); rosemary (0.5%) and the two combined treatments. 19. Cecum histology was not obviously changed with treatments, however, there are many crypts and goblet cells associated with moringa (1.0%); rosemary (1.0%) and the low level of both (R6) supplementation. 20. Liver histopathological sections showed some changes related to dietary additives, where the size of central vein, bile ducts, blood sinuses and the presence of Kupffer cells were different, especially between the control and experimental groups. 21. In general, no signs of hepatotoxicity were detected although some binucleated cells, fatty cirrhotic and congested areas could be seen, due mainly to, the higher metabolism of growing rabbits under study.Taking in consideration the previous studies by many investigators about the toxicity level of moringa leaves (600-800 mg/ kg LBW) and the recommended dose of rosemary leaves (80-120 mg/ kg LBW), it is concluded from our results that: Dietary supplementation with moringa dry leaves powder (0.5% or 1.0%), rosemary dry leaves powder (0.5% or 1.0%) or a combination of these supplements may be used as alternatives growth promoters, for enhancing productive performance of growing rabbits reared under heat stress conditions, without any adverse effect on their physiological responses. Since, it is suggested to use moringa dry leaves powder by level of 0.5% or combination of moringa and rosemary leaves, both of 0.5% in diets of growing rabbits reared under heat stress conditions. |