Chemical composition and apparent digestibility of a panel of dried microalgae and cyanobacteria biomasses in rainbow trout (Oncorhynchus mykiss)

Despite a growing interest in microalgae and cyanobacteria as potential sources of nutrients aquafeeds, little information is presently available on their nutritive value for carnivorous fish species. The aim this study was to evaluate chemical composition nutrient digestibility panel dried biomasses (MACB), using rainbow trout (Oncorhynchus mykiss W.) model. Nine test diets were obtained by mixing 80 parts reference diet, added with 20 g/kg acid insoluble ash an indigestible marker, each the following whole-cell biomass: Arthrospira platensis, Nostoc sphaeroides, two strains Chlorella sorokiniana, Nannochloropsis oceanica, Tisochrysis lutea, Phaeodactylum tricornutum, Porphyridium purpureum Tetraselmis suecica. measurements conducted (52.4 ± 1.5 g) kept six tank units including three 60-L vessels singularly stocked 12 fitted settling column faecal recovery. Per faeces collected over independent 10-day periods. Apparent coefficients (ADCs) dry matter, crude protein (CP), organic matter gross energy (GE) single MACB calculated difference relative those diet. MACBs had heterogeneous (CP, from 69%; Lipid, 5–27%; GE, 12.5?–22.6 MJ/kg basis) reflecting overall biodiversity. Most them can be considered virtually good minerals trace elements exhibit essential amino profile comparable or even better than that soybean meal commonly used feeds P. showing best profile. results allowed ranking into major groups. A first one, C. N. oceanica T. suecica, resulted markedly lower (P < 0.05) ADC (64–73%; 51–59%, respectively) compared second group purpureum, lutea (CP-ADC, 83–88%; GE-ADC, 74–90%) while tricornutum intermediate values. Overall, present confirms consistently reported role cell-wall structure/composition affecting accessibility digestive enzyme. Based outcomes, only actually meet requirements being aquafeeds provided mass production becomes more feasible cost-effective, hence attractive feed-mill industry near future.