Fibras musculares e estresse oxidativo de pintado amazônico alimentado com níveis de proteína

Abstract

In fish farming, protein has been the most expensive macronutrient in diets. Fish nutrition is the physiology area that studies the relationship between nutrient intake and animal development and metabolism. The dynamics of protein metabolism is influenced by body's nutrient needs and dietary protein and energy intake. The Pintado Amazônico is a crossbred hybrid of Pseudoplatystoma reticulatum × Leiarius marmoratus, that has been farmed due to its growth rate, feed conversion efficiency, carcass yield and absence of intramuscular bones. This study aimed to evaluate the effect of dietary digestible protein levels on the growth dynamics and oxidative stress in the white muscle of Pintado Amazônico. Four hundred and fifty-five juveniles of Pintado Amazônico were fed diets with seven different digestible protein levels (225; 250; 275; 300; 325; 350; or 375 g kg-1 ) for 75 days. At the end of the experiment, the fishs were fasted for 24 hours, anesthetized and euthanized to sample white muscle. The linear and quadratic effects of dietary digestible protein levels on the muscle fibers histology and concentration of metabolites and oxidative stress were determined. The results revealed that high dietary levels of digestible protein, despite increasing protein and free amino acids concentrations in the muscle, limits muscle hypertrophy and increase tissue exposure to oxidative damage in Pintado Amazônico farming.