Dietary effect of multi-strain prebiotics and probiotics on growth, hemato-biochemical parameters, intestinal histomorphometry, and resistance to hypoxia in juvenile tambaqui (Colossoma macropomum).

This study evaluated the effects of a multi-strain prebiotics and probiotics on the diet of tambaqui Colossoma macropomum. One hundred and fifty juvenile tambaqui (20.2  ± 3.6 g and 10.32  ±  5.78 cm) were randomly distributed in 15 experimental units with a volume of 80 L and fed for 45 days with a diet containing the symbiotic additive at five inclusion levels (0, 2, 4, 6 and 8 g kg feed). At the end of the period, growth performance, survival, hemato-biochemical and intestinal parameters, as well as the fish's resistance to stress were evaluated. The additive did not alter the growth performance, hemato-biochemical and intestinal parameters of the tambaqui. However, the hemato-biochemical parameters of aspartate aminotransferase (AST), plasma protein, hematocrit, glucose, triglycerides and cholesterol showed differences between treatments after the stress challenge. AST increased significantly during challenge and post-challenge. Plasma protein increased significantly during and after the challenge. The hematocrit was highest at 48 h after the challenge and lowest in the 2 g, 6 g and 8 g groups. Glucose was significantly reduced 24 h after the challenge, while triglycerides were lower 24 h and 48 h after the challenge. Cholesterol increased significantly in the challenge. There was an interaction between the factors sampling time and symbiotic concentration for hematocrit and glucose. In hypoxic stress situations, the 2 g concentration was more favorable for the fish. We recommend further studies with 2 g kg feed in trials lasting more than 45 days.