Researchers tested whether a medicinal mushroom called Phellinus gilvus could replace antibiotics in pig feed as a growth promoter. Over 28 days, piglets fed mushroom-supplemented diets grew as well as those given antibiotics while showing even better immune system activation. Unlike antibiotics that drastically changed the gut bacteria composition, the mushroom only slightly modified it while still reducing harmful E. coli bacteria. This suggests the mushroom could be a safer alternative to antibiotics in pig farming.