Growth performance, hepatic function parameters, histological changes of rainbow trout Oncorhynchus mykiss (Walbaum, ۱۷۹۲) and oxidative stability index of feed following dietary administration of Mix-Oil

The main objective of this study was to evaluate the effects of dietary supplementation of Mix-Oil (including: Thymus vulgaris (%۰.۵), Origanum vulgare (۲%) and Eucalyptus spp. (۲.۵%) essential oils) on growth performance, hepatic function parameters, tissue changes of rainbow trout and oxidative stability index of trout feed. Four groups of trout fish (with average weight ۳۱.۰±۰.۱ g) were fed with four diets containing: ۰, ۵۰, ۲۰۰ and ۴۰۰ ppm of Mix-Oil for ۸ weeks. SGR, ADG, CF, TGC, DGC, RGR and BWI were significantly higher and also FCR significantly lower were observed in ۲۰۰ and ۴۰۰ ppm groups compared to ۵۰ ppm and control groups (p<۰.۰۵). Significant increase in PER, LER, FCE and RFI in fish fed with ۲۰۰ and ۴۰۰ ppm Mix-Oil were observed compared with control and ۵۰ ppm groups (p<۰.۰۵), while, no significant differences having been observed among different treatments in terms of AST and ALT level (p>۰.۰۵). An increase in the number of hematopoietic cells in the kidney and significant increase in the length of the intestinal villous and the number of related epithelium cells having been seen in the ۴۰۰ ppm treatment group compared to the other studied treatment groups (p<۰.۰۵). By increasing the concentration of Mix-Oil, trout feed resistance has increased against oxidation. Although, the observed increments were only statistically significant in the ۲۰۰ and ۴۰۰ ppm Mix-Oil (p<۰.۰۵) compared to ۵۰ ppm and control groups. The results suggested that dietary administration of Mix-Oil at the level of ۴۰۰ ppm could improve growth performance of rainbow trout as well as increase the feed stability.    

کلیدواژه ها:

Mix-Oil ، Growth performance ، Oncorhynchus mykiss ، Tissue changes ، Oxidative stability index of feed