THERAPEUTIC EFFECTS OF THYME (THYMUS VULGARIS LINNEAUS) AND FENNEL (FOENICULUM VULGARE MILLER) ESSENTIAL OILS IN INFECTED RAINBOW TROUT, ONCORHYNCHUS MYKISS (WALBAUM)

The fish (84 +/- 1.02 g mean +/- SEM) were divided into 3 groups (N=15 in each group) as control (CNT), infected with Yersinia ruckeri (INF), and infected and essential oils (+EO). The CNT and INF groups were fed only with commercial fish feed. The +EO group was fed with feeds prepared with the rate of 10 ml herbal essential oils (mixed thyme and fennel) / 100 g feed during 21 days. The liver tissue (0.4 g) of fish was dissected in third day of the experimental period and mRNA transcription levels in liver tissue were determined by Real Time PCR analysis. INF and +EO groups exhibited decreased immunity against the challenging with Y. ruckeri infection (53.57 and 42.85 % mortality, respectively) when compared with CNT group (93.33 %). Gene mRNA transcription levels of tumour necrosis factor alpha (TNF-alpha), interleukin 1 beta (IL-1 beta), inducible nitric oxide synthesis (iNOS), serum amyloid A (SAA), that are responsible during the initiation and continuation of the inflammation increased in 1.86, 2.46, 1.62 and 55.7 fold change, respectively in INF group, whereas mRNA expressions of haptoglobin (Hp) decreased (1.2-fold change) in 3th day of experimental period. The +EO group eliminated the increase in all of the gene expressions.