Effects of reduced protein level and dietary amino acid supplementation on growth, body composition and intestinal morphometry of silver catfish ( Rhamdia quelen )

Abstract

The reduction in the protein level and the supplementation of lysine (Lys) and methionine (Met) in the diet were evaluated in the performance and intestinal morphometry of silver catfish (Rhamdia quelen). The study was used in a completely randomized design for 63 days, where 320 fish (26.33 ± 0.40 g) were distributed in 20 tanks (250 L, 16 fish each) and fed until the apparent satiety was reached. Five diets were formulated, a positive control [38% of crude protein (CP) (38CP)], a negative control [34% of CP (34CP)] and three test diets [34% of CP supplemented with Lys (34L), 34% of CP supplemented with Met (34M) and 34% of CP supplemented with Lys plus Met (34LM)]. Final weight and condition factor were greater in fish fed the 34LM diet than in those fed the 34CP diet (p < .05). Body lipid deposition was lower in fish fed the 34CP diet than other diets (p = .0002). In the fillet, there was a lower deposition of lipids in fish fed with 34L diet than in fish fed with 34M and 34LM diets (p <.0001). Fish fed the 34LM diet had a higher AA content in the plasma than those fed 34L and 34CP diets (p < .0001). The lower villus height was observed in fish fed the 34L diet compared to the 38CP diet (p = .021). It is possible to reduce 4% of the CP level in silver catfish diets with supplementation of Lys and Met.