Growth and oxidative parameters of Rhamdia quelen fed dietary levels of vitamin A

Abstract Vitamin A, a fat soluble compound is an essential nutrient for fish. The present study evaluated the effects of dietary vitamin A administered to juvenile silver catfish ( Rhamdia quelen ). Fish were fed semi-purified diets formulated to meet the protein and energy requirements of the species (37% CP and 3400 kcal kg − 1 DE). Five vitamin A levels were tested: 1090, 1180, 1750, 2610 or 2880 IU kg − 1 of diet. The growth, body composition, metabolic and blood parameters and oxidative stress biomarkers of juvenile silver catfish were studied after 70 days. Fish growth increased with an increase in vitamin A. The fish that were fed a 2610 IU kg − 1 vitamin A diet had better quality fillets, with more protein and less fat. No effects on hematological and biochemical parameters were noted. The high levels (1750, 2610 and 2880 IU kg − 1 ) of vitamin A improved the fish antioxidant defense system. Lower activity was observed for enzymes that act as antioxidants because retinoids and carotenoids acted as scavengers and donated electrons to reactive oxygen species, conferring enzymatic protection and contributing to the animal's energy economy. Based on the growth and fillet quality and oxidative results, we recommend a 2610 IU kg − 1 vitamin A diet for juvenile R. quelen . Statement of relevance Important to assess the nutrition and health of the silver catfish.