The effect of plant protein high levels in feed on biometric and histopathological parameters of rainbow trout

Abstract

Comparative studies of the effect of replacing animal protein in the structure of the diet with vegetable protein on biometric parameters and histopathological parameters of the liver of rainbow trout have been carried out on biological models of rainbow trout. Changes in trout carcass structure were revealed, indicating a change in live weight in the 1st control and 2nd experimental groups with a result of 3.7%, changes occurred in the 3rd group - 7.4%. Moreover, the changes in muscle mass in group 2 were expressed better than in the control group by 1.5%, similarly in group 3 – 12.8%. The weight gain of edible parts in group 2 was expressed better by 4.1% than in the control group, and in the experimental group 3 – 7.3%. The mass of in-edible parts in the study groups was also higher than in the control group. The yield of edible parts was higher in the 2 experimental group by 0.21%, in the experimental group 3 – 0.2%. When examining the liver tissue of the experimental group 3, some degenerative changes were revealed. Vacuolization of liver cells in the experimental group 3, which were fed a diet with vegetable protein high content in its structure, was significantly lower, and accordingly, in this group there were the smallest hepatocytes. Defects in cellular contacts in the liver, destruction, and proliferation of lymphohistiocyte cells into sinusoids were observed. Thus, a decrease of animal feed in the structure of predatory fish diets to the level of 25% leads to liver degeneration. This reactive adaptation of the liver to a new vegetable protein ingredient is of a short-term nature.