The present study aimed to evaluate the effects of poly‐β‐hydroxybutyrate (PHB)‐supplemented diets for rainbow trout (Oncorhynchus mykiss) fingerlings. For this purpose, three experimental diets were prepared to contain 0, 2, and 5% PHB; and each diet was tested in a completely randomized design for 60 days in quadruple groups of 22 fish per tank. The results showed that the inclusion of PHB in the diets did not affect the growth parameters such as mean weight gain, specific growth rate, and feed conversion ratio among treatments. There was also no effect of the PHB on chemical composition, PCR‐DGGE profile of the intestinal bacterial communities, total bacterial count, lactic acid bacteria, psychrophilic bacteria as well as the intestine and the liver histopathology of fish. However, the supplementation of 2 and 5% PHB in the diet significantly reduced total coliform counts, while 5% PHB diet additionally decreased Enterobacteriaceae counts. Both inclusion ratios resulted in significantly higher intestinal villus length and width at the end of the experiment. Considering the positive effects of dietary PHB on intestinal bacterial flora and villus sizes of rainbow trout fingerlings, it can be used as an alternative microbial control agent.

中文翻译：

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日粮聚β-羟基丁酸酯对虹鳟鱼，Onmyhynchus mykiss，鱼种生长参数，肠道菌群和组织病理学的影响

本研究旨在评估补充聚-β-羟基丁酸酯（PHB）饮食对虹鳟鱼（Oncorhynchus mykiss）的影响）鱼种。为此，准备了三种实验饮食，分别含有0、2和5％的PHB。并在完全随机的设计中对每组22条鱼每组22条鱼的四重组中的每种饮食进行了60天的测试。结果表明，日粮中添加PHB不会影响处理参数之间的生长参数，如平均体重增加，比生长速率和饲料转化率。PHB对鱼的化学成分，肠道细菌群落的PCR-DGGE图谱，总细菌数，乳酸菌，嗜冷菌以及鱼的肠道和肝脏组织病理学也没有影响。但是，在日粮中添加2和5％PHB会显着减少大肠菌群总数，而5％PHB日粮还会减少肠杆菌科计数。在实验结束时，两种包容率均导致肠道绒毛长度和宽度显着提高。考虑到膳食PHB对虹鳟鱼种的肠道细菌菌群和绒毛大小有积极影响，因此可以将其用作替代微生物控制剂。