Exigência de lisina para juvenis de Tambaqui (Colossoma macropomum CUVIER, 1818) com base no desempenho produtivo, morfohistológico e fisiológico

Abstract

The level of lysine requirement can be determined by methods such as dose response associated with the ideal protein concept, and tends to improve yield performance while maintaining fish health. The objective of this thesis was to determine the lysine requirement for maximum performance of tambaqui (Colossoma macropomum) juveniles, concomitantly, to verify the influence of amino acid on blood count and blood biochemistry, activity of digestive enzymes, intestinal and hepatic histomorphology, fillet chemical composition and yield trends of fish. The variables analyzed were validated by ANOVA, Tukey's test, and regression analysis (p<0.05). Tambaqui (33.88 ± 2.47g and 11.72 ± 0.36 cm) were fed diets containing 6.60, 9.72, 12.84, 15.96, 19.08 and 22.20 g. Kg-1 of total lysine (respectively: 0.00, 4.00, 8.00, 12.00, 16.00 and 20.00 g. Kg-1 of L-lysine). Relative weight gain, diet intake, fat content and index, anterior bowel height and perimeter, specific growth rates, protein efficiency and relative growth - weight, bowel weights and lengths, intestinal serous tunic , the gutted fish, and the protein and lipid contents of the fillets were not altered by the levels (p>0.05). Furthermore, no differences were found for hemoglobin, hematocrit, MCHC, eosinophil, monocyte, thrombocyte, glucose, triglyceride concentrations for amylase activity, lipase, and morphometric variables of the fish body (p>0.05). However, final weight (p=0.01), relative growth rate - length (p = 0.02), total weight gain (p=0.04), lysine efficiency (p=0.00 ) and apparent feed conversion (p = 0.00) differed at the level of 15.96 g. Kg-1 of total lysine. Lysine consumption (p = 0.00) and fin length (p=0.00) of tambourines linearly increased lysine levels. Intestinal tunics in the anterior muscle (p=0.00), anterior submucosa (p=0.00) and middle (p=0.01), and anterior mucosa (p=0.00) portions were influenced by diet as well as such as liver tissue, where hepatodystrophies were observed and increased hepatosomal index (p=0.04). The height of the midgut villi (p =0.01) was higher at the lowest L-lysine addition level (9.72 g.Kg-1 total lysine, 4.00 g L-lysine) and the perimeter level 12.84 g.Kg-1 of lysine overlapped with that of 22.20 g.Kg-1 of lysine. In the posterior intestine, height and perimeter (p=0.00; p=0.02) expressed variations not directly related to lysine levels. Acid mucins were higher in the anterior intestine at 22.20 g.Kg of lysine in the diet (p=0.001). MCV (p=0.00), MCH (p=0.00), total erythrocytes (p=0.02), lymphocytes (p=0.00) and neutrophils (p=0.00) were changed only in the initial period (p<0.05). Cholesterol (p= 0.00) and total leukocytes (p= 0.02) expressed influences not attributed to lysine (p=0.00). The tambourines of level 15.96 g. Kg-1 of lysine achieved higher growth (p=0.01) and higher intestinal (p=0.00) and blood (p= 0.01) protein concentration. The ratio between the standard and total length (p = 0.00) of the fish body was modified at levels 12.84 and 15.96 g. Kg -1 of lysine (p= 0.03). For crude skin (p=0.03), the best response was found at the level of 12.84 g. Kg -1 of lysine (p=0.03). Moisture content (p=0.00) and fillet minerals (p=0.01) were altered, respectively, with lysine 22.20 g. Lysine kg-1, and 6.60 and 22.20 g. Kg-1 of lysine. The maximum fillet with skin was estimated at 18.22 g. Kg -1 total lysine (p=0.001). Thus, it is concluded that tambaqui juveniles have a performance requirement of 15.96 g. Kg-1 of total lysine or 5.91% of dietary protein.