Effects of Diets Containing Different Levels of Prebiotic Inulin on the Growth Rate, Body Composition and Some Blood Parameters in Black Pacu (Colossoma macropomum)

Pacu is considered as one of the major sources of nutrition in the Amazon basin because of its high growth rate, low food expectation and resistance to diseases and the idea of using inulin in its diet can improve the culture of the species. In this study the effe0ct of different levels of prebiotic inulin on the growth rate, body composition and some blood parameters in black Pacu was studied. For this purpose 120 Pacu fish (6.50±0.05 g) were fed with 1, 2 and 3 g/kg   prebiotic inulin over a period of 60 days. The results showed that the highest percentage of body weight gained, specific growth rate and condition factor were obtained in 3 g/kg inulin, which were significantly different from other treatments (P<0.05). A significant positive effect was observed in feed conversion ratio (FCR) and protein efficiency ratio (PER) by adding 3 g/kg inulin. It decreased the amount of FCR and increased the amount of PER significantly. Also, there was no dead fish between treatments all during the period and the survival rate was 100%. Addition of inulin to the diet, improved the nutritional composition of the fish and the maximum amount of protein and fat and minimum amount of moisture were measured in 3 g/kg inulin. In hematological parameters, although there were no significant differences in the number of red blood cells, MCV, MCH and MCHC amounts, the maximum numbers of white blood cells and the highest amounts of hemoglobin and hematocrit with the significant differences to other treatments, belonged to 3 g/kg  inulin. Addition of 3 g/kg inulin can improve the growth rate, nutrient composition and immunity in Black Pacu.