Evaluation of the Ability of GroBiotic®‐A to Enhance Growth,Muscle Composition,Immune Responses,and Resistance Against Aeromonas hydrophila in Nile tilapia,Oreochromis niloticus |
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| Authors: | Z. L. Zheng K. Y. Wang Delbert M. Gatlin III J. M. Ye |
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| Affiliation: | 1. Fisheries Breeding and Healthy Cultivation Research Centre, South‐west University, Chongqing 402460, China and School of Veterinary Medicine of Sichuan Agriculture University, Sichuan 625014, China;2. Fisheries Breeding and Healthy Cultivation Research Centre, South‐west University, Chongqing 402460, China;3. Department of Wildlife and Fisheries Sciences and Faculty of Nutrition, Texas A&M University System, College Station, Texas 77843‐2258, USA;4. Yangzhou Fishery Technology Entending Station, Jiang Su, 225000, China |
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| Abstract: | This study was conducted to evaluate the potential of graded levels of GroBiotic®‐A to improve performance of Nile tilapia, Oreochromis niloticus, fed a 29% crude protein (CP) diet. A 29% CP diet was formulated and supplemented with 0, 0.4, 0.8, and 1.2% GroBiotic®‐A and compared to performance of fish fed a 33% CP diet. Enhanced weight gain and feed efficiency were generally observed in fish fed the diets supplemented with GroBiotic®‐A compared to the 29% CP diet. No significant differences in these responses were observed between fish fed diets supplemented with GroBiotic®‐A compared to those fed the 33% CP diet. Supplementation of 0.8 and 1.2% GroBiotic®‐A induced significantly lower condition factor and hepatosomatic index compared to fish fed the 29% CP diet, but those values were similar to that of fish fed the 33% CP diet. GroBiotic®‐A supplementation and protein reduction had no effect on the viscerosomatic index of fish or moisture, lipid, and protein content of muscle samples. However, muscle ash increased significantly with protein reduction (29% CP diet), but GroBiotic®‐A supplementation (0.8 and 1.2%) reduced muscle ash content. Activities of catalase and superoxide dismutase were markedly reduced in fish fed GroBiotic®‐A (0.8 and 1.2%) compared to those fed the control diet. GroBiotic®‐A supplementation also induced significantly higher neutrophil oxidative radical production compared to fish fed the 29% CP diet, but no significant difference was observed in comparison with the 33% CP diet. After 8 wk of feeding, exposure to Aeromonas hydrophila for 3 wk resulted in 40% (0.4, 0.8% GroBiotic®‐A) and 27% (1.2% GroBiotic®‐A) mortality and reduced signs of disease, while 47% mortality was observed in fish fed the 29% CP diet. Based on the result of this study, it is concluded that 0.8 and 1.2% GroBiotic®‐A positively influenced growth performance and feed efficiency of tilapia fed diets containing 29% crude protein to levels comparable to fish fed the 33% CP diet. GroBiotic®‐A supplementation also significantly increased neutrophil oxidative radical production as well as resistance to Ae. hydrophila infection. |
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