Effects of goosefoot (Chenopodium album) meal in diets on growth performance, body composition and digestive enzyme activity of rainbow trout (Oncorhynchus mykiss)

This study was designed to evaluate the growth, body composition and digestive enzyme activity as well as some antioxidant, immunological and haematological parameters of rainbow trout juvenile fed diets containing different levels (0%, 2.5% or 5%) of Chenopodium album powder as a feed additive for three months. Fish with an average initial weight 24.48 ± 0,05g, were divided into 3 groups in 9 tanks with stocking density of 40 fish/tank (triplicate tank were assigned for each experimental group). At the end of every month, respiratory burst (NBT), lysozyme and myeloperoxidase (MPO) activity as well as liver antioxidant enzyme activities (catalase, CAT; superoxide dismutase, SOD; glutathione peroxidase, GPx and glucose-6-phosphate dehydrogenase, G6PDH) and lipid peroxidation level (melondialdehyde, MDA) were analyzed. After three months of feeding, growth parameters such as final weight, weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR) and digestive enzymes like pepsin, trypsin, amylase and lipase as well as haematological profile; red blood cells (RBC) count, hemoglobin content (Hb), haematocrit value (Hct) and red blood cells indices including; the mean cell volume (MCV), mean cell hemoglobin (MCH) and mean cell hemoglobin concentration (MCHC) were examined. The results showed that final weight, WG, SGR and survival rate of fish significantly decrease (P˂0.05) in 5% C. album diet-fed fish group with highest FCR value than the control group. Pepsin, trypsin and amylase increased significantly in all experimental groups, whereas lipase activity not affected by the plant diets, as compared to the control group. It was observed that G6PDH and SOD activities were significantly decreased (P˂0.05) in the liver of all the treated fish groups on the 30th and 60th days of experiment, respectively. Again, a significant reduction (P˂0.05) was found in CAT and MDA levels in the fish fed the diets with the plant powder compared to the control on the 30th, 60th and 30th days of experiment, respectively. Also, feeding with 2.5% diets for thirty days and 5% diets for sixty days led to significant decrease in hepatic GPx activity, as compared to the control. Blood NBT levels were not affected by the dietary treatment, but MPO values were significantly decreased (P˂0.05) in 5% diet-fed fish group at the end of 60th and 90th days. On the other hand, serum lysozyme activity was significantly increased (P˂0.05) in all experimental groups during study periods. However, feeding with 2.5% C. album diet caused significant decrease (P˂0.05) in Hb, Hct, MCH and MCHC values, meanwhile, feeding with 5% herbal diet led to significant reduction (P˂0.05) in RBC and Hct values of fish, compared to the control group. As a general conclusion, addition of C. album to diets of trout exerted positive effect on digestive enzymes, compromised growth performance at different levels, and undesirable effects on antioxidant, immunological and haematological parameters. Keywords: Chenopodium album, rainbow trout, growth, body composition, digestive enzymes, antioxidant status, immunological and haematological parameters