Effects of dietary supplementation with oregano essential oil on prevention of the ectoparasitic protozoans Ichthyobodo salmonis and Trichodina truttae in juvenile chum salmon Oncorhynchus keta
| Autor: | Shinya Mizuno, Makoto Hatakeyama, Mahito Miyamoto, Shigehiko Urawa, Yoshitaka Sasaki, Hiroshi Ueda, Nobuhisa Koide, Shoichi Tada |
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| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Parasitic Diseases Animal Zoology Aquaculture Aquatic Science law.invention 03 medical and health sciences chemistry.chemical_compound law Origanum Oils Volatile Animals Juvenile Carvacrol Kinetoplastida Flagellate Ecology Evolution Behavior and Systematics Essential oil Skin Ciliate biology 04 agricultural and veterinary sciences biology.organism_classification Antimicrobial Hatchery Diet Oncorhynchus keta 030104 developmental biology chemistry Oligohymenophorea Dietary Supplements 040102 fisheries 0401 agriculture forestry and fisheries Oncorhynchus Phytotherapy |
| Zdroj: | Journal of Fish Biology. 93:528-539 |
| ISSN: | 0022-1112 |
| Popis: | The present study performed three experiments to establish a practical prevention strategy for the ectoparasitic flagellate Ichthyobodo salmonis and ciliate Trichodina truttae in hatchery-reared juvenile chum salmon Oncorhynchus keta using dietary supplementation with oregano essential oil. Experiment 1 showed that a diet supplemented for 3 weeks with 0.02% oregano essential oil significantly prevented infection with I. salmonis and T. truttae in juveniles reared in small tanks. Experiment 2, in outdoor hatchery ponds, demonstrated that the oregano treatment completely prevented I. salmonis infection for 52 days and T. truttae infection for 38 days. Oregano-treated juvenile mortality attributable to infection with these protozoans also decreased to 7.6% of control juvenile mortality, confirming the utility of this treatment in cultured O. keta. Physiological analyses of the oregano-treated juveniles elucidated the treatment's safety in relation to their metabolism, osmoregulation, natural immunity and olfactory responses and also detected carvacrol (a major component of oregano essential oil which shows antimicrobial activity) on the skin. In experiment 3, exposure of the two protozoans to oregano essential oil revealed a weak antiparasitic action on the body surface of the juvenile O. keta. The overall results demonstrate that dietary oregano supplementation is a practical prevention strategy for I. salmonis and T. truttae in hatchery-reared juvenile O. keta and suggest the possibility that its anti-parasitic action is attributable to a component of the oil that emerges onto the skin of the body of the fish. |
| Databáze: | OpenAIRE |
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