Effect of dietary protein on growth, feed conversion, body composition and survival of pike perch fingerlings ( Sander lucioperca )

Triplicate groups of pike perch ( Sander lucioperca ) juveniles were fed six experimental diets containing protein levels varying from 263 to 619 g kg −1 dry matter (d.m.) for 56 days. Dietary protein was supplied by graded amounts of fish meal (with 720 g kg −1 crude protein). Crude lipid and gross energy content of 101–107 g kg −1 and 19.9–20.6 MJ kg −1 remained constant between experimental diets. Pike perch with an initial body weight of 1.05 ± 0.05 g were randomly distributed in 18 tanks of two similar recirculation systems and fed on gradually decreasing feeding rates of 10 to 6% of their body weight per day. Growth performance and feed conversion increased with dietary protein level from 263 to 549 g kg −1 d.m. but did not decline at highest dietary protein level. Protein efficiency ratio declined linearly with increasing dietary protein. Survival ranged between 89.7 and 93.9% and was not affected by dietary composition. Dry matter and crude lipid content of pike perch fingerlings decreased with increasing dietary protein supply and significantly the lowest dry matter and crude lipid levels were observed in fish fed diets containing 619 g kg −1 of crude protein. The dietary protein requirement for pike perch fingerlings calculated by broken‐line and second‐order polynomial regression ranged between 529 and 577 g kg −1 , respectively.