Effects of several macerated citrus oils on health parameters of rainbow trout (Oncorhynchus mykiss) under high stocking density

Abstract

The interplay between dietary components and antioxidant systems in fish physiology is crucial for aquaculture. Citrus fruits, renowned for their high content of bioactive antioxidants, have attracted attention for their antioxidant features in fish. The purpose of this study was to investigate the dietary effects of using essential oil from macerated oils of lemon peel (Citrus limon) (MOL), orange peel (Citrus sinensis) (MOO) and grapefruit peel (Citrus paradisi) (MOG) on growth, proximate composition, hematological, antioxidant parameters of rainbow trout (Oncorhynchus mykiss) subjected to high stocking density stress. Fish (110 ± 10.95 g) were randomly introduced to three trial groups (1% of MOL, MOO and MOG). At the end of feeding period (42-day), the results showed that the three trial groups had significant effects on the feed conversion ratio (FCR), especially in the MOG (P<0.05). The FCR value in MOG was remarkably 0.81. In the study, the lowest dry matter and ash levels were detected in MOO, moisture content in MOL, but the highest fat (6.82 ± 0.82) and protein (15.85 ± 0.74) levels were found in MOG. There were significant differences in proximate composition and red blood cell (RBC) (1.73 ± 0.07 in MOG), hemoglobin (Hgb) (8.97 ± 0.43 in MOL), hematocrit (Hct) (23.92 ± 1.09 in MOL), mean corpuscular hemoglobin concentration (MCHC) (38.22 ± 0.34 in MOG) between the control and all groups (P<0.05). The results showed that glutathione peroxidase (GPx), catalase (CAT) and glutathione reductase (GR) activities in all treatment groups were decreased and malondialdehyde (MDA) level was increased in the MOO group activity (P>0.05).