Palm kernel expeller (PKE)-based feed for brine shrimp Artemia production: effects on growth, biomass, and microbial composition

The brine shrimp Artemia is one of the most popular live food species used in aquaculture. The natural food for this crustacean is microalgae, bacteria, and detritus, but they can be grown using a variety of agricultural by-products, each having advantages and disadvantages. In this study, the efficacy of palm kernel expeller (PKE), a by-product of the oil palm industry, as a potential feed alternative for raising Artemia in an indoor tank culture system was investigated. Analysis on the nutritional composition showed that PKE contains 15% protein, 6% lipids, 51% nitrogen-free extract (NFE), 14% fiber, and 6% ash of dry weight, which made it a suitable aquafeed. Prior to utilization, PKE was mixed with seawater at a ratio of 1 kg of raw PKE powder to 4-L seawater, filtered through a 50-micron plankton net, and then incubated for at least 24 h. Based on the findings of a 14-day feeding trial, the optimal duration of PKE incubation and feeding concentrations necessary to grow nauplii to adults during tank cultures were one day of incubation (PKE1D) and maintaining 19-cm turbidity, where Artemia growth and biomass production were at their highest levels. Artemia were able to consume PKE particles, which microscopic examination revealed a completely filled stomach. The metagenomics analysis confirmed the presence of beneficial bacteria such as Lactobacillus, Bifidobacterium, and Candidatus aquiluna belonging to the Actinobacteriota phylum in both the PKE solution and Artemia rearing water. Artemia biomass fed with PKE1D contained more than 45% protein, 21% NFE, and 9% lipids, making it nutritionally adequate for many aquaculture species. The findings of this study support that PKE is a suitable feed for Artemia and that this alternative is ideal to be used for an indoor tank culture system.