Effects of diets with whole plant-origin proteins added with different ratios of taurine:methionine on the growth, macrophage activity and antioxidant capacity of rainbow trout () fingerlings.

A 70-days feeding trial was performed to determine the effect of diets with whole plant-origin proteins added with different ratios of taurine:methionine on the growth, macrophage burst activity and antioxidant capacity of rainbow trout () fingerlings. Triplicated groups of 70 fingerlings of an initial weight of 0.54±0.1 g (mean±±SD) were fed diets with soy protein isolate and powder as protein sources (46% crude protein) and added (10 g/kg diet) with different taurine and methionine ratios: 0.0 and 10.0 (diet T0/M100), 2.5 and 7.5 (diet T25/M75), 5.0 and 5.0 (diet T50/M50), 7.5 and 2.5 (diet T75/M25) and 10.0 and 0.0 (diet T100/M0), respectively. At the end of the trial, growth performance, lipid and protein contents in liver and muscle, macrophage burst activity and liver antioxidant activity, were determined. The growth performance, macrophage burst activity and antioxidant activity were improved as the taurine increased in the diets. The ratio of 7.5 and 2.5 g/kg of taurine:methionine in diets with SPI and powder as protein sources (diet T75/M25), seems to be the best inclusion for rainbow trout fingerlings.