Hayom shiva v'arbaim yom, shehaym shisha shavuot va'chamisha yamim baomer

Why is it that my brother was able to eat chickens when he was living in Paraguay but is allergic to them here? It's because he's allergic to the things you consume along with meat in the U.S. In this country, many farmed animals are given hormones in their food (to induce growth) as well as antibiotics (to keep them alive through conditions that would otherwise kill them when veterinary care is minimal or non-existent).