Levels of carbohydrates and lipids in diets for juveniles of tambaqui (Colossoma macropomum): productive, physiological and isotopic turnover variables

Author(s)

Lidiane Cristina Gonçalves de Sandre

• Document type: Doctoral Thesis
• Press: Jaboticabal. 2016-02-26.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
• Defense date: 2016-02-03
• Advisor: Dalton José Carneiro; Rosângela Kiyoko Jomori Bonichelli

Abstract

The tambaqui Colossoma macropomum is the most produced native fish in Brazil in continental freshwater aquaculture. Little is known, however, about the qualitative and quantitative requirements of nutrients for the native species used in aquaculture. From this context, the objective of this study was to evaluate the potential of using lipids and carbohydrates in diets for juveniles of tambaqui, through the analyses of performance, body composition, energy metabolism, and the isotopic turnover of nutrients in the muscle, liver and visceral fat. In the pre-experimental phase, 3600 tambaqui juveniles were used which received a diet based on plants from the C3 photosynthetic cycle for a period of 70 days, in which the body tissues would express the isotopic signature similar to the offered diet. After this period, 1080 fish (with a weight of approximately 10 g) were randomly distributed into 24 tanks and were fed diets based on plants from the C4 photosynthetic cycle, for 120 days. The experiment was carried out with six treatments and four replications in a 3 x 2 factorial scheme consisted of three levels of nitrogen free extract (41, 46 and 51% NFE) and two levels of ether extract (4 and 8% EE). The highest level of inclusion of the NFE (51%) caused a reduction in the consumption and consequently in the growth of the animals. The increase in the level of EE to 8% increased the deposition of body fat, reduced the coefficients of digestibility of the nutrients and energy, increased serum triglycerides and the fat in liver and muscle. There was a protein-sparing effect for the growth of the tambaquis fed with 46% of NFE, since these animals presented the best results for weight gain, protein efficiency rate, retention efficiency of crude protein, and participation of the crude protein in the weight gain. The experimental period of 120 days was sufficient to reflect the isotopic composition of the diets and, for the δ13C, the muscle was the best tissue to demonstrate the differences between the diets, with a more accelerated isotopic turnover in animals receiving the diets with lower levels carbohydrates (41 and 46%) and lipids (4%). For the deuterium, the isotope values allowed the projection of the exponential isotopic turnover and the rates were more accelerated in the liver and visceral fat, for the diets containing greater levels of carbohydrates and/ or lipids. Thus, the tambaqui can be affirmed to use the lipids as efficiently as carbohydrates to maximize the use of protein. The results indicate that the best balance between the levels of dietary NFE and EE was 46 and 4%, respectively, without impairing growth and avoiding an excessive accumulation of fat in juveniles of tambaqui. (AU)

• FAPESP's process: 12/15656-6 - Levels of carbohydrates and lipids in diets for tambaqui juveniles (Colossoma macropomum) and isotopic turnover of carbon-13 and deuterium-2
• Grantee: Lidiane Cristina Gonçalves de Sandre
• Support Opportunities: Scholarships in Brazil - Doctorate