Immune function of an animal can be modulated by administration of a composition that includes algae meal or beta glucan. The algae meal can be made by growing Euglena using particular methods and conditions, including certain continuous, semi-continuous, fed-batch, and repeat batch methods in sterile fermenters. Euglena provides a form of beta glucan that is different from other organisms, where the beta glucan is predominantly unbranched beta-1,3-glucan. Use of algae meal and beta glucan produced by the disclosed processes can improve the wellbeing of an animal or human, and may augment or even replace the use of antibiotics in certain circumstances.
