Carbohydrate molecule size affects the metabolic and digestive dynamics of jundiá (Rhamdia quelen)

Abstract

This experiment was conducted to study the effects of carbohydrates with different molecular sizes on growth performance, feed utilization and composition, activity of digestive enzymes, plasma and hepatic metabolites of jundiá (Rhamdia quelen). Triplicate groups of jundiá (4.08 ± 0.005 g) were stocked in 12 tanks with stocking density of 25 individuals per tank and fed for 40 days with four isonitrogenous diets (37%) and isocaloric diets (3,200 kcal/kg) containing fructose (FRU), sucrose (SUC), maltodextrin (MALDEX) or corn starch (CS). The results showed no significant differences for growth variables and digestive enzymes. Fish whose diet received maltodextrin showed higher levels of deposited body fat and hepatosomatic index. Moreover, the above‐mentioned treatment resulted in lower concentrations of glucose and cholesterol in the plasma of jundiá, higher levels of triglycerides, and lower reserves of glucose and liver glycogen. However, fish fed the starch‐based diet presented higher moisture content, crude protein deposition, and body protein retention coefficient. In that same treatment, the jundiá presented higher levels of plasma glucose and liver protein. In conclusion, the efficiency of using digestible carbohydrates in iso‐nutritional diets for jundiá depends on the size of their molecular structure. The corn starch was the best dietary carbohydrate source for jundiá, based on feed utilization and composition and greater synchronicity between energy utilization and protein synthesis.

Synchronic use of protein and carbohydrate sources for improved growth performance in Jundiá

“…The jundiá juveniles in this study showed a higher DSI when consuming diets containing fructose. This observation also occurred in another study conducted when jundiá were fed with fructose (Corrêia et al, 2019). It is hypothesized that this monosaccharide is absorbed more quickly and thereby changes the osmotic balance of enterocytes, increasing water influx into the cell (Baldisserotto et al, 2007).…”

“…The fish exhibited heavier final weights, higher specific growth rates, higher protein deposition, and less fat deposition when using rice in the form of raw starch. Corrêia et al (2019) The jundiá juveniles in this study showed a higher DSI when consuming diets containing fructose. This observation also occurred in another study conducted when jundiá were fed with fructose (Corrêia et al, 2019).…”

“…The fish exhibited heavier final weights, higher specific growth rates, higher protein deposition, and less fat deposition when using rice in the form of raw starch. Corrêia et al (2019) observed greater protein deposition and retention of body protein and less fat deposition in the juvenile jundiá fed with a combination of casein (200 g/kg), fish meal (313.5 g/kg), and corn starch (275.0 g/kg) as sources of protein and carbohydrate, indicating that this diet has an appropriate metabolic balance.…”

“…In this study, the jundiá juveniles did not exhibit any significant changes in the activity of amylase and acid protease, despite the different combinations of protein and glucose sources in the experimental diets. Additionally, jundiá showed no significant difference in amylase activity when fed different dietary glycidic sources (Corrêia et al, 2019; Gominho‐Rosa et al, 2015). In our experiments, the lower activity of maltase observed in fish after the consumption of diets with fructose, especially in the CASFRU treatment, was an expected situation, as fewer substrates for enzymatic action resulted from the digestive process.…”

“…However, the results from the studies on daily weight gain and specific growth rate indicate that jundiá do not exhibit full growth potential. In a study developed by Corrêia et al (2019), it was observed that jundiá fed with a diet containing corn starch, associated with fish meal and casein as protein sources, exhibit greater synchronicity between energy use and protein synthesis. Therefore, the objective of this work was to combine sources of proteins and carbohydrates with different molecular structures that would therefore require different digestion and metabolization times by the fish, in an attempt to ascertain which mixture promotes better dynamics in the use of nutrients for maximum expression in the performance of jundiá juveniles.…”