An algal biomass and supernatant derived from at least one species of algae exhibits anti-inflammatory and immune response modulating properties. Methods of reducing the symptoms of or treating a condition or disease in an animal, including bovine mastitis and Bovine Respiratory Disease Complex, and the pain and discomfort caused by osteoarthritis, injury or overexertion or muscle and connective tissue strains, comprises administering to the animal in need thereof an algal biomass or supernatant derived from at least one species of algae, or an extract, derivative or biologically active compound derived from the algae species, biomass or supernatant, or compositions thereof.
