Fontes de carboidratos na alimentação de juvenis de Pacu (Piaractus mesopotamicus)

Abstract

Objective of this work was to evaluate the effect of diets with different carbohydrate sources on the growth and metabolism of juvenile pacu (Piaractus mesopotamicus). Thus, three experiments were carried out, from three diets containing corn, broken rice or sorghum. In the first study, 375 juveniles, with 12.13 ± 0.09 g, were distributed in 15 tanks (280 L), fed an extruded diet three times a day, until satiety, for 60 days. The design was completely randomized with three treatments and five replications. Results were submitted to ANOVA and the means were compared by the Duncan test (5%). In the second study, animals were submitted to postprandial glycemic evaluation. Therefore, they remained fast for 12 hours. Blood collection occurred at time zero (before refeeding) and 1, 3, 6, 9 and 12 hours post-feeding. In the third study, 100 animals with 56.32 ± 0.85 g were used to determine the digestibility of experimental diets in four cylindrical tanks with a conical bottom (190 L) for faeces decantation, performing a collection of one diet at a time, with four replicates. There was no mortality; the final weight, weight gain, average daily gain, relative weight gain, condition factor, food intake, specific growth rate, total length, feed conversion, triglycerides and very low density lipoprotein, alanine aminotransferase, protein retention coefficient and digestibility were similar among diets (P > 0.05). High-density lipoproteins, total proteins, globulins, hepatic protein, hepatic ammonia, hepatic glucose, hepatic glycogen, body protein, carcass yield were higher with sorghum (P < 0.05). Low density lipoprotein was higher when fed corn. Plasma glucose was higher in treatments with corn and broken rice. The use of sorghum led to lower values of hepatosomatic index, visceral index, digestive index, albumin, cholesterol and intestinal quotient. The enzymes amylase, lipase, trypsin and maltase reduced their activities in the animas fed with the sorghum diet. The broken rice diet resulted in higher lipid levels, lipid retention coefficient, free amino acids in the liver, hepatic ammonia, and hepatic glucose. For dry matter, protein and ash in body composition, there was no difference. In the glycemic curve, glycemia peaks were observed with 3.5 and 4 hours after ingestion of the diets containing sorghum and rice, respectively, while for corn the highest value was after 12 hours of feeding. The digestibility of dry matter, protein and lipids did not differ between treatments. In conclusion, this studies have demonstrated that corn, broken rice or sorghum in the diet of pacu juveniles are suitably used by the species, without any adverse effect on growth and survival. Corn denotes a metabolic profile of better utilization of dietary carbohydrates. Broken rice and sorghum generate an increase in amino acid catabolism to maintain energy production processes. There is an increase in the production of nitrogen compounds of excretion in both broken rice and sorghum treatments. Sorghum showed higher carcass yield and protein content in whole fish