Defatted Biomass of the Microalga, Desmodesmus sp., Can Replace Fishmeal in the Feeds for Atlantic salmon

Abstract

Microalgal biomass is a potential feed ingredient that can replace fishmeal and ensure sustainability standards in aquaculture. To understand the efficacy of the defatted biomass from the marine microalga, Desmodesmus sp. a 70-day feeding study was performed with Atlantic salmon (Salmo salar) smolts. Three groups of fish (av. wt. 167 g) were offered either a control feed (without the microalga) or the microalga-containing (10/20%) feeds. At the end of the feeding period, the growth indices (condition factor, specific growth rate) and survival of the microalga-fed fish were not significantly different from the respective values of the control fish, but the feed conversion ratios were inferior. The proximate composition of the whole body of salmon from the three groups did not vary significantly. Compared to the control fish, the 10% alga-fed fish had lower lipid content in their filet. The protein and lipid digestibility in the three feeds did not differ significantly, but the digestibility of energy in the 10% alga-feed was significantly lower than that of the control feed. Furthermore, comparison of the distal intestinal proteome of Atlantic salmon revealed that the expressions of Alpha-2-HS-glycoprotein-like (Ahsg), Myosin-11 isoform X1 (My11) and Dihydrolipoyl dehydrogenase, mitochondrial-like (Dld) were altered by the microalgal feeding. Examination of the physiological status of the fish based on the serum antioxidant capacities did not reveal any alga-feed-related differences. Moreover, the expression of the selected immune and inflammatory marker genes and the micromorphological observations did not indicate any aberration in the intestinal health of the microalga-fed fish. It is possible to include 20% of defatted Desmodesmus sp. in the feeds of Atlantic salmon.

Nannochloropsis oceania-derived defatted meal as an alternative to fishmeal in Atlantic salmon feeds

“…On the contrary, such an increase was not detected in the fish fed on 20% alga-containing feeds. In our earlier study on Desmodesmus , a similar trend in SOD activities was noted [22]. Furthermore, the mRNA level of sod was apparently higher in the 10% alga-fed group compared to the level in the 20% alga-fed group.…”

“…The SGR values obtained in the present study were slightly lower than those reported earlier [22, 26]. The TGC values in the present experiment were higher than those obtained by Sørensen et al [15], but were in the same range as reported by Hatlen et al [26].…”

Recovery of Protein Concentrates From Microalgal Biomass Grown in Manure for Fish Feed and Valorization of the By-Products Through Anaerobic Digestion

“…In order to satisfy this demand, the utilization of microalgae as an alternative to fishmeal is being widely studied in different fish species (Olvera-Novoa et al, 1998;Patterson and Gatlin, 2013;Kiron et al, 2016;Sørensen et al, 2016). Most microalgae are rich in fiber, mineral salts, trace-elements, vitamins, polyunsaturated fatty acids, chlorophylls and essential amino acids (EAA), fulfilling requirements of most commercial fish feed and avoiding supplementation of vitamins and amino acids (Vizcaíno et al, 2014).…”

Responsible Fishmeal Consumption and Alternatives in the Face of Climate Changes

“…However, because of the recent increasing cost of fishmeal, researchers have started evaluating the economic feasibility and optimum usage of these novel proteins as fishmeal substitutes. Partial fishmeal replacement with algae is also possible (Kiron et al, 2012;Al-Asgah et al, 2016;Abdel-Warith et al, 2016;Radhakrishnan et al, 2016;Kiron et al, 2016;Kissinger et al, 2016), especially in tropical areas where they are found in plentiful amounts. Kiron et al (2016) observed that partial substitution of fishmeal with defatted biomassof Desmodesmus sp.…”

“…Partial fishmeal replacement with algae is also possible (Kiron et al, 2012;Al-Asgah et al, 2016;Abdel-Warith et al, 2016;Radhakrishnan et al, 2016;Kiron et al, 2016;Kissinger et al, 2016), especially in tropical areas where they are found in plentiful amounts. Kiron et al (2016) observed that partial substitution of fishmeal with defatted biomassof Desmodesmus sp. in the feed of Atlantic Salmon does not have any adverse effects on the specific growth rate, condition factor, protein efficiency ratio and whole body proximate composition of fish.…”