Dietary Effects of a Short-Term Administration of Microalgae Blend on Growth Performance, Tissue Fatty Acids, and Predominant Intestinal Microbiota in Sparus aurata

Abstract

Given the potential of microalgae as new aquafeed ingredients, this study focuses on using a blend of microalgae, Tisochrysis lutea, Nannochloropsis gaditana, and Scenedesmus almeriensis, as a dietary ingredient for feeding Sparus aurata juveniles. The growth performance, carcass composition, tissue fatty acid profile, and intestinal microbiota were evaluated after a 30 day-feeding period. A microalgae-free diet was used as control, and three experimental diets were formulated containing 5%, 15%, and 25% of the microalgae blend (MB-5%, MB-15%, and MB-25%, respectively). After 7, 15, and 30 days of feeding experimental diets, biological samples were taken. Growth performance and nutrient utilization were not significantly modified at the end of the experiment. Microalgae inclusion tended to decrease body lipids and affected the fatty acid profile, especially MB-25 diet increased DHA levels. Diet MB-25 promoted appropriate microbial diversity, favoring the presence of probiotic bacteria, such as Lactobacillus, and significantly influencing the fatty acid composition and lipid metabolism in fish. In conclusion, using a short pulse of dietary administration of 25% microalgal blend in S. aurata modulates the intestinal microbiota and lipid composition while maintaining growth performance.

Potential Effects of Microalgae-Supplemented Diets on the Growth, Blood Parameters, and the Activity of the Intestinal Microbiota in Sparus aurata and Mugil cephalus

“…Fish fed the M25-SA diet showed higher WG, SGR, and FE values than those fed the CT-SA diet. These results are in accordance with other studies where S. aurata fed supplemented microalgae extract diets also showed higher growth values without adverse effects in allometric growth (K) of fish [11,12,41]. This fact could be the cause or the consequence of the significant increase in the intestinal length, with improved feeding efficiency of fish fed diet supplemented with microalgae ingredients compared to those fed a control diet, given that as denoted by Molina-Roque [11] and Perera et al [12], a higher intake of diets formulated with a high content of vegetable ingredients is associated with a significant increase in the intestine length index, as well as the absorption area of the intestinal microvilli, with improved feeding efficiency of fish fed diets supplemented with plant ingredients compared to those fed without plant ingredients.…”

“…Although its use as an aquafeed ingredient for the fattening phase of fish is not widespread, in recent years, there has been a growing interest in exploring the potential of microalgae as functional components in aquafeed design for fish, replacing traditional ingredients such as fish and plant protein. These microalgae offer various health benefits, enhance growth, and improve the quality of fish products [11][12][13][14]41].…”