Coccidiosis is a costly parasitic disease to the poultry industry with multiple prevention methods being explored to control its impact. One approach under development is the use of -glucans, which are carbohydrates from cell walls of various plant species. The first study evaluated the feeding effects of algae- derived -glucans on performance and responses of broilers during a coccidiosis challenge. Cobb 500 broilers (n=1280) were fed a control diet, control supplemented with 150 g/MT Algamune (BG), 100 g/MT Algamune ZPC (BGZn), or 0.01% Salinomycin (Sal). On d 15, challenged birds received mixed Eimeria inoculum. Measurements were taken on d 7, 14, 21, and 28, and lesion scores assessed on d 21. The challenge resulted in reduced BW, and higher feed conversion ratio (FCR) was observed in the challenged birds with Sal and BGZn. Escherichia coli (E. coli) is normally commensal to the gastrointestinal tract, but certain serotypes cause disease in domestic poultry. A subsequent study was conducted to evaluate the feeding effects of algae-derived glucan (1,3 -glucan) on performance of broiler chickens during an E. coli challenge. Cobb 500 broilers (n=900) were fed a control diet, control + 25 mg/kg of -glucan, or control + 100 mg/kg of -glucan. On d 0, litter was sprayed with E. coli inoculum. Measurements were taken on d 7, 14, 21, and 28. -glucan supplementation increased BW gain andlowered FCR. The results from these studies offer some insight to the effects of -glucans on poultry and their potential to offset negative effects caused by infectious challenges.