Abstract: A microbial biomass, made from algae, bacteria, fungi, yeast, or combinations thereof, provides a feed for animals raised either in agriculture or aquaculture. A feed additive, and a therapeutic composition can also be made from a microbial biomass of algae, bacteria, fungi, yeast, or combinations thereof. The feed, feed additive, and therapeutic composition can comprise one or more proteins, peptides, antibodies, antibody fragments, or a combination thereof, wherein said proteins, peptides, antibodies, antibody fragments, or a combination thereof are non-native to the microbes of the biomass. The biomass can have therapeutic, bioactive, nutritional, and/or immunogenic properties.