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Influence of digestible protein levels on growth and feed utilization of juvenile meagre Argyrosomus regius

Abstract:

This study investigates the effect of digestible protein levels in experimental diets for meagre (Argyrosomus regius). A group of 253 fish, 52 g of mean weight, was distributed in 12 tanks, three replicates per treatment. Four isolipidic diets (170 g kg-1 crude lipid) with different digestible protein levels (350 g kg-1, 430 g kg-1, 490 g kg-1 and 530 g kg-1) were formulated using commercial ingbkp_redients. The trial lasted 62 days. Meagre fed diets 430, 490 and 530 g kg-1 obtained higher TGC (2.47, 2.57, 2.69 × 10-3, respectively) than fish fed diet 350 g kg-1 (2.14 × 10-3). Group of fish fed diet with 350 g kg-1 DP showed the lowest ammonia excretion level. According to the in vitro digestibility trial diets with 350 and 430 g kg-1 DP released less amino acids in comparison with diet with 49% DP, although in vivo digestibility test did not show significant differences among diets 430, 490 and 530 g kg-1 DP. Using the quadratic regression, optimal digestible protein intake according to the ECR for rearing juvenile meagre was recorded in 0.8 g DP/100 g fish and day.