Exigência proteica em dietas para alevinos do dourado (Salminus brasiliensis)

Abstract

The dietary protein requirement of dourado fingerlings was evaluated by two feeding trials where the crude protein concentrations varied from 32.29 to 57.63% in trial I, and from 33.93 to 53.61% in trial II. Fingerling initial weights were 0.75 and 5.68 g, for trial I and II, respectively. Experimental diets were formulated with semipurified ingredients and were isoenergetic within each feeding trial. Fish were fed to apparent satiation, twice a day (9 and 4 p.m.), for 29 days in trial I and 94 days in trial II. Regression analysis revealed a linear increase in weight gain as the dietary protein concentration increased in Trial I, indicating that the protein requirement of dourado fingerlings from 0.75 to 3.04 g is, at least, 57.6%. In trial II, with bigger-size fish, 45.4% crude protein was estimated as the protein requirement for maximum weight gain by polynomial regression.