Effects of dietary supplementation of safflower seed oil (Carthamus tinctorius) on rainbow trout growth and physiological parameters (Oncorhynchus mykiss W.).

The use of polyunsaturated fatty acid-rich vegetable oils is also rapidly increasing in the fish culture farming sector as a means of greater industrial and environmental sustainability. This paper describes the effects of safflower seed (Carthamus tinctorius) oil (SO) as a feed additive at 0.25%, 0.5%, 1% and in a control group on growth performance, meat quality, fatty acid, digestion, and immunological, oxidative and histopathological parameters of rainbow trout. At the end of the experiment, there were significant differences between the experimental groups in specific growth rates, live weight gains and feed conversion ratio values, except for daily feed intake and survival ratios. The 1% SO group improved the product quality and weight gain rate of fish by up to 20% compared to the control. The enzyme activity of pepsin, amylase, lipase and trypsin in the 1% SO group was significantly different compared to the control group. Serum lysozyme, myeloperoxidase and plasma nitroblue tetrazolium levels changed significantly in the 0.5% SO and 1% SO groups compared to the control group, except for the 0.25% group. Liver superoxide dismutase, glutathione peroxidase and malondialdehyde levels were significantly different in all groups, especially in the 0.5% and 1% groups compared to the control group. From a histological standpoint, there were no abnormalities in either the control or experimental groups. Interactions with conjugated linoleic acid and oleic acid, dietary proteins and digestive enzymes were examined for their potential to preserve immunological parameters and affect protein digestibility and phenolic bioavailability at the cellular level. Based on the findings, SO may be used alternatively as a feed additive for the overall health and growth of rainbow trout.