Fishmeal substitution by Iberian pig meal and vegetable proteins blend and inclusion of Isochrysis aff. galbana (T-Iso) in diets for gilthead seabream (Sparus aurata L.): Effects on growth and feed utilization efficiency

Research was carried out into the effect of partial and total fishmeal (FM) replacement by a vegetable and animal proteins blend, as well as the inclusion of microalgae in diets for gilthead seabream (Sparus aurata L.). Fish of 64 g on initial weight were fed until apparent satiation for 88 days. The control diet (FM100) contained FM as the main protein source, whilst in FM25, FM10 and FM0 diets, the FM was replaced 75%, 90% and 100%, respectively, by a proteins blend consisting of Iberian pig meal (IPM) and vegetable protein meals. FM0+ was similar to FM0 diet but included 50 g/kg of Isochrysis aff. galbana (T-Iso). Results obtained in the final bodyweight and the specific growth rate indicate that the FM25 and FM100 diets achieved similar performances. An improvement in growth performance and nutrient utilization was observed in the FM0+ diet with respect to the FM0 diet. The highest retention efficiencies of protein, energy and essential amino acids were found in FM100 and FM25 diets. In conclusion, up to 75% FM substitution by a vegetable and animal proteins blend in on-growing gilthead seabream is feasible, in addition, the inclusion of Isochrysis aff. galbana (T-Iso) improves the growth and retention efficiencies in a non-FM diet.