Evaluation ofArthrospirasp. enzyme hydrolysate as dietary additive in gilthead seabream (Sparus aurata) juveniles

The aim of this work was to evaluate the effects of the dietary inclusion ofArthrospirasp. enzyme hydrolysate on gilthead seabream (Sparus aurata)juveniles in a 128-day feeding trial. Algal hydrolysate was tested at low inclusion level, namely, 2 and 4%, against a control diet withoutArthrospirasp. supplementation. At the end of the feeding trial, fish body weight was recorded for growth evaluation. No significant differences were found among the experimental groups regarding growth performance or nutrient utilization, despite the fact that those animals fed with diets enriched withArthrospiradisplayed higher trypsin, chymotrypsin, and leucine aminopeptidase enzyme activities, compared to fish fed with control diet. The ultrastructural study of the intestinal mucosa also revealed increased microvilli length and absorptive capacity in fish fed withArthrospirasp. diets, especially at 4% inclusion level.Arthrospirasupplementation was also responsible for lower lipid oxidation in muscle tissue, as well as for remarkable colour differences in skin, compared to control animals. These results suggest, overall, that low dietary supplementation with this microalgal hydrolysate might improve not only the intestinal ultrastructure and functionality but also muscle pigmentation and antioxidant capacity of juvenile gilthead seabream.