Amplifying Processing of Livestock in the United States Act or the A-PLUS Act This bill directs the Department of Agriculture to revise its regulations to allow livestock market agencies (e.g., auction market owners) to hold an ownership interest in, finance, or participate in the management or operation of a meat packer with a cumulative slaughter capacity of (1) less than 2,000 animals per day or 700,000 animals per year for cattle and sheep, and (2) less than 10,000 animals per day or 3 million animals per year for hogs.