EATING QUALITY AND GROWTH OF RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) ON FEED WITH DIFFERENT ADMIXTURES OF LEAF NUTRIENT CONCENTRATE

The effects, with regard to eating quality and to growth, of leaf nutrient concentrate (LNC) in fish feed for rainbow trout (Oncorhynchus mykiss (Richardson)) were investigated in two consecutive studies. In the first study the admixture of LNC was made on an isocaloric basis, primarily by replacing a quantity of carbohydrates from the control feed. The control diet and two diets with 25% and 45% LNC, respectively, were administered for 4, 8 and 12 weeks. In the second study the LNC partly replaced protein and lipid from fish meal in the control feed. A control diet and two diets with 12.5% and 25% LNC, respectively, were administered for 16 weeks. The LNCs were obtained from lactic-acid-fermented green leaf juice mixtures. The effects of LNC in the feed indicated that: rainbow trout did not have a satisfactory growth on feed with 25% or 45% LNC incorporated whereas fish on 12.5% LNC in the feed did not differ from fish on the control feed; rainbow trout on LNC feed did not have the delicate acidulous taste characteristic of fresh rainbow trout; the muscle lipid level was reduced with increased LNC level of the feed; the relative level of monounsaturated fatty acids decreased whereas polyunsaturated fatty acids increased with an increased level of LNC, and saturated fatty acids.