THE EFFECT OF DIETARY-FAT IN MARKET RAINBOW-TROUT ON GROWTH DYNAMICS,SPECIFIC GROWTH-RATE AND TROUT HEALTH

An experiment on the culture of 17,122 market rainbow trouts (Oncorhyn chus mykiss) was conducted in 1996; their initial individual weight wa s 0.082 kg and they were kept in concrete-made pools with 1m(3) water volume. The objective of the experiment, which lasted 133 days, was to determine the effect of an addition of 4% contents of three kinds of oils (fish, rapeseed, sunflower oils) on feed efficiency and some othe r parameters, including specific growth rate (SGR in % per day), growt h dynamics in rainbow trout and trout health. Two imported feeds for r ainbow trout with 13.35% (4) and 18.49% of fat (5) were used in this e xperiment parallelly with diets of our own formulation (1, 2, 3 with 1 1-12% of fat). The highest values of specific growth rate were determi ned in fish receiving imported feed 5 with 18.49% of fat. Growth dynam ics of rainbow trout receiving diets 1, 2, 3 of our own formulation an d imported feed 4 was almost identical. This parameter was not substan tially influenced by the kind of oil used. The growth of trout receivi ng imported feed 5 with 18.49% of fat was dynamic and faster. The five kinds of diets did not affect the trout health evaluated by hematolog ical and biochemical parameters. The lowest (P < 0.05) value of serum total protein content was determined in the group receiving diet 5 wit h highest fat content.