Which Act would regulate the exposure of livestock feed to contaminants?

The Feeds Act is the correct choice because it specifically governs the composition and safety of livestock feed, ensuring that it is safe for animal consumption and free from contaminants that could harm livestock or enter the food supply. This Act establishes standards for the manufacture, distribution, and labeling of animal feeds, which helps maintain the health of livestock and supports overall food safety in animal agriculture.

Other options like the Pesticide Control Act focus primarily on the regulation of pesticides used in agricultural settings and do not directly address livestock feed safety. The Food Safety Regulation concerns itself with food products for human consumption rather than animal feed, although there may be some indirect connection to animal products destined for human consumption. The Fertilizers Act regulates the use of fertilizers for plants and does not pertain to livestock feed.