Comparative effects of garlic, black seed, and black caraway encapsulated essential oils powder on the histopathology of rainbow trout (Oncorhynchus mykiss) gills, kidneys, and intestines

Natural compounds derived from plants possess antimicrobial, antifungal, and anti-inflammatory properties, enhancing the immune system, promoting growth, and reducing stress in fish. This study investigated the effects of dietary supplementation with encapsulated powders of essential oils from garlic, black seed, and black caraway on the vital organs of rainbow trout (Oncorhynchus mykiss), specifically the kidneys, gills, and intestines. Due to the natural instability of essential oils, encapsulation was employed to preserve their therapeutic properties. Initial extraction of pure essential oils was followed by identification of their components using gas chromatography-mass spectrometry (GC-MS) and subsequent encapsulation using a fluidized bed dryer for improved stability. Rainbow trout were divided into experimental groups: a control group fed a basal diet, a black seed group (basal diet + black seed), a garlic group (basal diet + garlic), a black caraway group (basal diet + black caraway), and a combined group (basal diet + a combination of the three essential oils). The fish were fed these diets for eight weeks. Histopathological examinations revealed significant damage in the gills of the black seed and combined oil groups, characterized by hyperplasia and inflammation. In the kidneys, the combined group exhibited pronounced proteinuria and hemorrhage, while increased villi length and mucosal cell hyperplasia were noted in the intestines of this group. Results indicated that garlic oil had the most positive effect on tissue health, showing the least damage. Thus, garlic oil is recommended as a dietary supplement for improving the health of rainbow trout in sustainable aquaculture practices.

کلیدواژه ها:

Essential Oils ، Histopathology ، Rainbow Trout ، Encapsulation ، Dietary Supplementation.