The present study was undertaken to examine the effects of oregano essential oil on the growth performance, blood glucose levels, body composition and intestinal morphometry of Nile tilapia reared in salinized water at 10 g/L for 64 days. The experiment was set up as a completely randomized design with five treatments and four replicates, in which a control diet and four diets containing increasing concentrations of oregano essential oil (0.75, 1.5, 2.25 and 3.0 g/kg) were tested. The best results for the growth parameters were obtained with the oregano essential oil inclusion level of 0.75 g/kg, but did not differ (p > .05) from inclusion levels of 0.0, 2.25 and 3.0 g/kg. Conversely, the treatment including the oil level of 1.5 g/kg was the only one to produce significantly (p < .05) lower results. The body composition and blood glucose were not significantly affected. Intestinal morphometry analysis revealed a significant effect on villus length, which increased with the proportion of oregano essential oil added to the diet; accordingly, the inclusion level of 3.0 g/kg provided the best results for this variable. Therefore, the addition of oregano essential oil at 3.0 g/kg in the diet of Nile tilapia cultured in salinized water may act as a stimulant to intestinal villus development and, consequently, as a growth promoter.

中文翻译：

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牛至（Origanum vulgare）精油作为盐化水中饲养的尼罗罗非鱼（Oreochromis niloticus）鱼种日粮的添加剂

本研究旨在研究牛至精油对在10 g / L盐化水中饲养64天的尼罗罗非鱼的生长性能，血糖水平，身体成分和肠道形态的影响。实验设置为完全随机的设计，共进行了五次治疗和四次重复，其中测试了对照饮食和四种饮食中牛至精油浓度的增加（0.75、1.5、2.25和3.0 g / kg）。牛至精油的夹杂物含量为0.75 g / kg可获得最佳的生长参数结果，但与 0.0、2.25和3.0 g / kg的夹杂物含量没有差异（p > .05）。相反，含油量为1.5 g / kg的处理是唯一能够显着产生油污的处理方法（p <.05）较低的结果。身体成分和血糖没有受到明显影响。肠形态分析表明，对绒毛长度有显着影响，随牛至精油的添加比例增加。因此，该变量的包含量为3.0 g / kg提供了最佳结果。因此，在盐化水中培养的尼罗罗非鱼饮食中添加3.0 g / kg的牛至精油，可能会刺激肠绒毛发育，从而促进生长。