RESUMO
In this study, boric acid was added to the rainbow trout (Oncorhynchus mykiss) feed at ratios of 0.00%, 0.01%, 0.05%, 0.10%, and 0.20%. The feeding period of this study continued for 90 days. The effect of boric acid on the growth parameters and nutritional composition of rainbow trout were investigated. In this research, effects on live weight gain (LWG), amount of feed intake, feed conversion rate (FCR), protein efficiency rate (PER), specific growth rate (SGR), survival rate, economic conversion rate (ECR), and economic profit index (EPI) were evaluated as growth parameters. As for nutritional contents, the total crude protein, lipid, raw ash, and humidity ratios were calculated. Rainbow trout with an initial weight of 92.04 g reached up to 195.05 ± 1.69 g, 202.69 ± 1.94 g, 217.53 ± 2.84 g, 195.25 ± 2.18 g, and 181.20 ± 1.89 g, respectively in the different levels of boric acid at the end of the trial period. The best growth performance was obtained in the group with 0.05% boric acid added, while the lowest growth performance was observed in the group with 0.20% boric acid added. It was concluded based on the results of this study that the amount of boric acid up to 0.05% in the fish feed positively affected the growth parameters and the addition of higher amounts had either no benefit or negative effects on the growth performance of rainbow trout. Furthermore, boric acid in feed affected the nutritional composition of fish meat.