THE EFFECTS OF ANTIOXIDANT NEOX AND LECITHIN ON PRODUCTION AND BODY GROWTH INDEXES OF RAINBOW-TROUT (ONCORHYNCHUS-MYKISS)

Results are presented of pilot trials aimed attesting the effect of the n-mixed antioxidant in loose form (BHT-based compound) on live weight gain and body growth in the market rainbow trout. The trials were conducted in laminated pools with water flow, at an average water temperature of 11.4-degrees-C, amount of dissolved oxygen 9.4 mg/l and oxygen saturation of water 86 %. The experimental fish was rainbow trout with the starting weight of 180 to 263 g. Eight and nine experimental groups by 300 fishes each with one replication were established in trials A and B at an experimental locality. Similarly like in the preceding trials (Rehulka, 1994), an addition of 0.5 and 1 % rapessed lecithin absorbed on wheat meal or amylostabile (trial A) and wheat bran (trial B) was tested besides gradated doses of Neox and Neox forte (100, 200 and 300 mg/kg of the pellet). Pellets with 200 mg Kurasan per kg (quinoline derivative, the synonyms of which in foreign substances are Ethoxyquin, Santoquin, Santoflex, Ethoquin) were used as a positive control, as its liquid form has become disadvantageous with respect to applications in large-scale technologies of biofactor supplements and medicated feeds. The study of body growth was based on correlation and regression analyses, in which regression lines of linear type and relative weight gain were determined from the proportion of regression parameter (b(yt): y(i)BAR).100. In both trials, the highest relative weight gain was attained in the experimental fishes fed the pellets with the highest dose of Neox (300 mg/kg) against the positive and negative control (22.58 and 27.89 % vs 19.73 and 25.29 % and 17.20 and 23.44 respectively). Positive results were also recorded for the mixture of Neox and lecithin, so it was possible to draw a conclusion (from the results shown in Tabs. II and V) that Neox did not have depressive effects on the growth of 1+ rainbow trout within 100 days. The negative control with the lowest relative weight gain in both trials (5th experimental group of trial A - 17.20 %, 4th experimental group of trial B - 23.44 %) indicates that the addition of antioxidant and lecithin to feed is advantageous. Fig. 1 shows best the differences in the dynamics of changes in live weight. The results of the trials aimed at the effects of both tested lecithin doses on the growth of 1+ rainbow trout (Tab. II) showed insignificantly higher relative weight gain except the 6th experimental group in trial A (experimental groups 6,7, 8 and 9) in comparison with the negative control represented by the 2nd experimental group. Unlike the results in trial A, the relative weight gains were insignificantly lower in trial B in the experimental groups given 0.5 % lecithin and antioxidant Neox and Kurasan. These results enable to state that the addition of lecithin to pellets for 2+ rainbow trout at a dose of 0.5 to 1 % does not influence the growth ability of 1+ rainbow trout. A reason for the favorable economic assessment consists in feed conversion in the experimental group with the highest dose of Neox (300 mg/kg) in comparison with the positive (200 mg Kurasan per kg) and negative control, which can be expressed by the values 1.57 of feed conversion ratio (against 1.81 and 2.03).