Effects of replacing fish meal with different levels of irradiated and non-irradiated pea powder on growth indices and thyroid hormones (T3 and T4) of Rainbow trout (Oncorhynchus mykiss)

Effects of replacement of irradiated and non-irradiated pea powder with fish meal as an alternative protein source in Rainbow trout (Oncorhynchus mykiss) diet were investigated on growth parameters and thyroid hormones (T3 and T4) levels. For this purpose, 245 rainbow trouts with an average 60 ±4 g weight of were randomly divided into seven treatments. Dietary treatments included 20, 30 and 40% replacement of fish meal with peas without irradiation, 20, 30 and 40% replacement of fish meal with pea-irradiated (to reduce anti-nutritional factors) and no manual feed peas (control treatment), respectively. To eliminate anti-nutritional compounds peas, the electron beams were used. Fish rearing was done in 300 l fish tank for 8 weeks. Bioassays were conducted on days zero and 56. Bioassay tests were conducted at the beginning and at the end of the experiment. Also on day 56, the blood samples of the fish were undertaken to determine the amount of thyroid hormone. Results showed that irradiated and non-irradiated pea replacement up to 40% in the diet of Rainbow trout had no negative impact on fish growth parameters compared with the control diet. Furthermore, the use of irradiated and non-irradiated peas up to 40% had no negative impact on thyroid hormone secretion. The results showed that pea powder as a vegetable protein is a good substitute for fish meal in Rainbow trout diet.