Carbohydrates are interesting in feeds because they are cheaper than other macro nutrients. They can contribute to pellet processing, and they can reduce the catabolism of dietary proteins for energy purposes. The ability of fish to deal with carbohydrates is species dependent and varies according to the complexity of the carbohydrates. Tambaqui (Colossoma macropomum), a species of freshwater fish from South America, is a very interesting biological model due to its frugivorous eating habit. The objective of this work was to verify some intermediary metabolism variables of tambaqui after oral administration of glucose and starch.
Tambaqui (111.5 ± 49.8 g) were submitted to oral administration of 200 mg/100 g BW of glucose, starch, and saline solution (control). Blood was collected at 0 (basal), 3, and 6 hours after administration (n=9). Were assessed plasma glucose, serum triglycerides, serum total lipids, hepatosomatic index and hepatic glycogen. The experiment was carried out in a 3x3 factorial, corresponding to 3 different substances administered in 3 samplings time with 3 repetitions each. The results were submitted to two-way ANOVA, followed by Tukey’s test at 5%.
No mortality was recorded. The interaction between administered substance and sampling time displayed significant differences just in plasma glucose concentration (p<0.00001). The fish that received glucose showed a higher concentration of plasma glucose at the 3 hours, while in those that received starch, the highest concentration was observed at 6 hours. No differences (p>0.05) were observed in serum triglycerides, hepatosomatic index and hepatic glycogen. In serum total lipids was observed a significant effect of sampling time, with higher concentration observed at 6 hours. In conclusion, starch has been demonstrated to be metabolized slower than glucose by tambaqui.