The effect of different levels of L-isoleucine in compound feeds on the growth of tilapia (Oreochromis niloticus)

Four diets were developed, including the control (main diet), which actually contained 34.00% crude protein, while the other three contained protein close to this value, taking into account the measurement error, and isoleucine in groups 2, 3 and 4, 4.9%, 8.51% and 12.12%, respectively. The study of the effect of L-isoleucine additives in compound feeds on the growth of tilapia (Oreochromis niloticus) showed that varying the concentration of this amino acid has a significant effect on fish growth rates. Adjusting dosages makes it possible to achieve more efficient use of feed in aquaculture conditions. It was found that when the amino acid isoleucine is introduced into the diet, feed conversion decreases by 0.64 points with an additional concentration of 1.42 g/kg of feed (4.9%), by 0.88 points with additional administration of isoleucine by 1.55 g/kg of feed (8.51%), by 0.76 points with an additional concentration of 1.68 g/kg of feed (12.12%). It was shown that the best group with the lowest feed conversion rate was the 3rd group, in which the amino acid isoleucine was introduced into the diet by 8.51% more than in other groups. The optimal level of isoleucine administration in tilapia feed is 1.55 g/kg of feed (8.51%). It was found that the ash content in the carcass of O. niloticus increased by 0.8%, fat — by 1% in muscles compared with the control.