The efficiency of growing rainbow trout (Oncorhynchus mykiss) at different levels of lysine and methionine in feeding

Abstract

The article considers the issue of the effectiveness of the use of complete feed with different levels of lysine and methionine for the cultivation of rainbow trout. Experimental studies on this yearling rainbow trout є (Walbaum, 1792) were conducted in the farm «Shipot» Perechyn district of Transcarpathian region. The aim of the experiment was to establish the effect of different levels of amino acid nutrition of this yearling trout on its performance. For this purpose, five experimental groups were formed by the method of analogues. The experiment lasted 55 days and was divided into two periods: equalization (5 days) and basic (50 days). During the equalization period, the experimental fish consumed feed of the control group. In the basic period, the level of lysine and methionine in experimental feeds for different experimental groups of trout ranged from 2.7 to 3.1% and from 0.85 to 1.05%, respectively. Trout were fed 6 times a day during the growing season. The required amount of feed was calculated according to the indicators of individual weight of young and the temperature of the environment at the time of feeding. Trout were grown in ponds at a water level of 1 m. Weighing of experimental young trout was performed once every 5 days. It is proved that the reduction of lysine content to 2.7% and methionine to 0.85% in compound feed for this year trout weighing more than 10 g causes a significant (p<0.05) decrease in fish productivity. In particular, it was found that feeding compound feeds with the above amino acid levels helps to reduce trout weight by 10.4% and reduce growth rate by 9.1–19.9% compared to fish fed lysine and methionine at level 2.9 and 0.95%, respectively. The increase in these indicators in the feed for trout this year is accompanied by some positive trend to increase their productivity, but no significant difference has been established. In the course of research it was determined that the feed consumption per 1 kg of weight gain in this year of trout, which received feed with a content of lysine 3.0% and methionine 1.0% were lower by 10.3%, and with the content of these amino acids at level 2.7 and 0.85%, respectively — 17.1% higher compared to fish that consumed food with a content of lysine 2.9 and methionine 0.95%. The use of complete feed with different levels of lysine and methionine for feeding trout this year did not significantly affect the safety of fish, which was in the range of 82.0–83.1%. For the production of trout products in terms of maximum productivity and economic optimization criteria, for feeding trout weighing more than 10 g, it is recommended to use complete feed with a level of lysine — 3.0% and methionine — 1.0%.