美国因禽流感疫情而限制对巴西鸡肉产品的进口。

Group 1 - The core point of the article is that the United States has imposed restrictions on imports of chicken products from Brazil due to an outbreak of avian influenza [1] Group 2 - The restrictions are a response to concerns over the spread of avian influenza, which could impact the poultry industry [1] - This decision may affect Brazil's chicken exports, which are significant to its economy [1]