Optimal protein requirements of young Arctic charr (Salvelinus alpinus) fed practical diets

Abstract

Young Arctic charr, Salvelinus alpinus (L.), mean weight 2.56 ± 0.02 g, were fed nine isoenergetic (˜16.6 MJ digestible energy (DE) kg−1) practical diets formulated to supply digestible crude protein (DCP) at 40g kg−1 increments from 230 to 550g kg−1, for 84 days. Mean weight gain (MWG) and specific growth rate (SGR) were determined every 14 days while carcass composition was determined at the start and end of the experiment. Growth responses attained the highest values in the fish fed the diet with 350 g kg−1 DCP. Carcass moisture gain, protein gain and apparent net lipid accumulation increased as DCP levels increased to a maximum at 350 g kg−1 after which there were no differences among treatments. Total carcass lipid and lipid gain decreased as dietary DCP increased up to 470 g kg−1 with no differences thereafter. Apparent net protein accretion decreased with increasing DCP levels up to 350 g kg−1 after which there were few differences among treaments. Protein requirements were estimated by fitting MWG and SGR data to broken line regression, quadratic and saturation kinetics models. Results from these analyses suggest that dietary DCP should be provided at between 340 and 392 g kg−1 (equivalent to ˜370 and 420g kg−1 crude protein) for optimal growth of young Arctic charr reared in similar conditions.

Effects of dietary protein level on growth and utilization of protein and energy by juvenile mangrove red snapper (Lutjanus argentimaculatus)

“…Although PER and NRE tended to decrease from 1.34 to 1.12 as dietary protein increased from 20 % to 45 % in 5 % increments, a linear increase (0.23 to 0.27 g) in nitrogen gain was generally observed until the requirement level was met (Pongmaneerat and Watanabe, 1991). This shows that excess protein is catabolized to provide energy for growth (Cowey, 1995;Gurure et al, 1995). The FCR of diets ranged from 0.35 to 0.45 in the present study.…”

Effect of different dietary protein and lipid levels on growth and survival of juvenile Australian redclaw crayfish, Cherax quadricarinatus (von Martens)

“…Growth response (in terms of average weight gain in grams) to DP concentrations was fitted to a quadratic model (second‐order polynomial) (Zeitoun et al. 1976; Gurure et al. 1995; Shearer 2000).…”

“…1995; Shearer 2000). This model fits dose–response relations on the basis of mathematical and/or biological principles (Gurure et al. 1995).…”

Effect of dietary protein level on the growth and survival of pre-adult freshwater crayfish Cherax quadricarinatus (von Martens) in monosex culture

“…Statistical differences in feed intake, protein intake, PER, and biomass (g m −2 ) were established at the end of the experiment. Growth responses, in terms of average weight gain in grams, to DP concentrations were fitted to the quadratic model (second‐order polynomial) (Zeitoun, Hullrey, Magee, Gill & Bergen 1976; Gurure, Moccia & Atkinson 1995; Shearer 2000): where Y is the response variable, χ is the protein level as a percentage, α is the intercept of the curve, β and c are the slopes, and gives the inflexion point. This model fits dose–response relationships based on mathematical and biological principles (Gurure et al 1995).…”