Biochar de casca de arroz em dietas para alevinos de curimatá (Prochilodus sp.)

Abstract

Biochar, or biocharcoal, is a material obtained from the pyrolysis of agricultural waste, such as rice husks and sugarcane bagasse. In recent years, it has stood out as a food additive in animal diets, with the potential to improve weight gain, optimize physiological parameters, and promote well-being. The objective was to evaluate the effects of including rice husk biochar in diets for curimatás (Prochilodus sp.). For this purpose, 200 fingerlings were distributed in experimental boxes (10 individuals/unit), kept in an open system with constant aeration and daily cleaning, and fed diets with 0, 1, 2, 3, and 4% biochar for 70 days. At the end of the experiment, performance, feed efficiency, blood, and liver variables were evaluated for four animals per repetition. Principal component analysis (PCA) showed that the first component was associated with blood variables (triglycerides, cholesterol, albumin, glucose, CHCM, HCM, VCM, hemoglobin, hematocrit, and erythrocytes), IHS, and performance parameters (feed intake and condition factor). The second component was explained, for the most part, by zootechnical variables (feed intake, weight gain, specific growth rate, and final weight at 30 and 70 days). Univariate statistics indicated that the inclusion of biochar progressively reduced feed intake at 30 and 70 days. Among the biochemical variables, the inclusion of biochar increased blood glucose. In the hematological profile, diets with 4% biochar significantly increased hematocrit and hemoglobin, while HCM and CHCM increased from 2%. In conclusion, rice husk biochar functioned primarily as a physiological modulator. Its most significant effects included increased glucose levels, improved hematological parameters (hematocrit, hemoglobin, HCM, and CHCM), and reduced feed intake, with no significant impact on the final body weight of the fish. Thus, its effect is focused on enhancing metabolic and blood responses, rather than directly promoting growth.