PCA of performance, gastrointestinal proteins, and digestive enzymes of tambaqui (Colossoma macropomum) fed lysine

ABSTRACT The current study aimed to identify the variables that best explain performance using Principal Component Analysis (PCA), in addition to detecting gastrointestinal proteins, amylase, and lipase in juvenile tambaqui (Colossoma macropomum) fed diets with lysine. The diets contained 6.60, 9.72, 12.84, 15.96, 19.08, and 22.20 g.kg−1 of total lysine and were supplied to the fish (n = 180; 10 fish per tank) for 90 days. The data that were inserted into the productive performance equations were collected during the experimental period to perform the PCA. At the end of the 90 days, the fish were anesthetized, and gastrointestinal tissues were collected for analysis of protein concentration and enzymology. As a result, PCA showed that PC1 and PC2 (components 1 and 2) explain 80.40% of the performance. In PC1, the highlighted variables were feed and protein efficiencies and final weight, contributing 19.59, 17.31, and 17.12%, respectively. In PC2, the variables that contributed most were dietary intake (14.06%) and weight gain (13.42%). The previously mentioned variables showed high projections in the regression analysis (P<0.001). Gastrointestinal proteins varied; however, it was not possible to detect through post-hoc tests which diets influenced them (P>0.05). Enzyme activities did not vary (P>0.05). Feed efficiency is the variable with the most significant contribution to PC1, and diets containing up to 22.20 g.kg−1 of lysine do not influence gastrointestinal proteins nor amylase and lipase enzymes in juvenile tambaqui.