美国农业部：美国至6月30日牛肉库存3.957亿磅。

Group 1 - The core point of the article is that the U.S. Department of Agriculture reported that the beef inventory in the U.S. as of June 30 is 395.7 million pounds [1] Group 2 - The reported beef inventory figure indicates a significant measure of supply within the agricultural sector, which can impact pricing and market dynamics [1] - This inventory level may reflect trends in beef production, consumption, and overall market health in the U.S. [1] - The data is crucial for stakeholders in the beef industry, including producers, distributors, and investors, as it provides insights into supply chain conditions [1]