Tasco® made of sun dried brown seaweed (Ascophyllum nodosum) by Acadian Seaplants Ltd., has displayed prebiotic like properties with ruminants and may be an alternative to antibiotic growth promoters. Tasco® was fed to male broiler chickens for 35 days in a series of three trials which compared Tasco® to the prebiotic inulin and an antibiotic and determined Tasco®’s optimal inclusion level for broilers. Trials investigated Tasco® fed at 2.0% for 14 days only and examined its effects in a 45 day trial and when subjected to microbial challenge. Tasco® enhanced growth comparatively to inulin and the antibiotic virginiamycin. Alteration of physiological variables in all three trials supported the possibility of microflora changes in the gut as a mode of action. Low levels of Tasco® (0.25% and 0.5%) were consistently effective at improving growth. Microbiological profiles, currently under way, will aid in final determination of Tasco®’s qualifications as a prebiotic.