Dietary microbial phytase exerts mixed effects on the gut health of tilapia: a possible reason for the null effect on growth promotion

卷:115

Hu, Jun ; Ran, Chao ; He, Suxu ; Cao, Yanan ; Yao, Bin ; Ye, Yuantu ; Zhang, Xuezhen ; Zhou, Zhigang

Huazhong Agr Univ

关键词: Microbial phytase;    Gut;    Adhesive bacteria;    Cytokines;    Tilapia;   

DOI  :  10.1017/S0007114516001240

学科分类：食品科学和技术

【 摘 要 】

The present study evaluated the effects of dietary microbial phytase on the growth and gut health of hybrid tilapia (Oreochromis niloticus female xOreochromis aureus male), focusing on the effect on intestinal histology, adhesive microbiota and expression of immune-related cytokine genes. Tilapia were fed either control diet or diet supplemented with microbial phytase (1000 U/kg). Each diet was randomly assigned to four groups of fish reared in cages (3 x 3 x 2 m). After 12 weeks of feeding, weight gain and feed conversion ratio of tilapia were not significantly improved by dietary microbial phytase supplementation. However, significantly higher level of P content in the scales, tighter and more regular intestinal mucosa folds were observed in the microbial phytase group and the microvilli density was significantly increased. The adhesive gut bacterial communities were strikingly altered by microbial phytase supplementation (0.41< similarity coefficient < 0.54). Stimulated intestinal inflammation and stress status were observed in the fish fed diet supplemented with microbial phytase, as indicated by the up-regulated intestinal expressions of the cytokine genes (tnf-alpha and tgf-beta) and hsp70. In addition, the gut microvilli height was significantly decreased in the phytase group. These results indicate that dietary microbial phytase may exert mixed effects on hybrid tilapia, and can guide our future selection of phytases as aquafeed additives - that is, eliminating those that can stimulate intestinal inflammation.