The effect of different sources of dietary starch on growth performance and blood biochemical parameters of rainbow trout (Oncorhynchus mykiss)

An experiment was conducted to study the effect of feeding the various starch sources on body weight gain, feed conversion ratio, hepatosomatic, viscerosomatic indexes and some blood biochemical parameters of rainbow trout (Oncorhynchus mykiss). Wheat flour, corn and starch by-product from production of wheat gluten used in the extruded fish feed and fed to three hundred fish (average weight 157 ± 1 g) for 60 days, where distributed in 12 fiberglass tanks (300-liter) as a completely randomized design. The results showed that various dietary sources of starch did not impact feed intake, specific growth rate, and feed conversion ratio of fish in the total period. The lowest viscerosomatic index and the highest carcass efficiency of fish were seen by feeding corn extruded feed (P<0.05). Feeding the wheat flour increased the serum concentration of aspartate aminotransferase (P<0.05); while, triglycerides, cholesterol, total protein, glucose, high-density lipoprotein, and low-density lipoprotein were not affected by the experimental diet. Overall, corn could be completely replaced with wheat flour, as the main starch source of extruded feed without any adverse effect on growth performance and blood biochemical parameters of rainbow trout; while more research is needed to apply the starch by-product from production of wheat gluten in the fish extruded diet.