Registration of a new toxicant for feral swine in the United States requires meeting test standards under the Federal Insecticide, Fungicide, and Rodenticide Act as regulated by the U.S. Environmental Protection Agency. A primary requirement is to compare the palatability and efficacy of the toxicant to a non-toxic challenge diet in a 2-choice test; however, no standardized challenge diet exists for feral swine. We conducted a series of 2-choice tests to examine four potential challenge diet items for preference by feral swine. We found that feral swine consumed the most and spent the most time feeding on rough rice (i.e., seed rice), although dog food and rough rye could not be wholly discounted as potential challenge diets. Rough rice was preferred, provided adequate nourishment, and is readily consumed by free-ranging feral swine. Therefore, we conclude that rough rice is an appropriate challenge diet for incorporating into 2-choice tests to meet test standards for evaluating the effectiveness of an oral toxicant for feral swine.