USDA Higher Education Challenge Grants can be used for international programs. Michel Wattiaux in Dairy Science has one that funds students to study in Mexico. CALS International Programs can help with proposal preparation.
Projects supported by the Higher Education Challenge Grants Program will: (1) address a State, regional, national, or international educational need; (2) involve a creative or non-traditional approach toward addressing that need that can serve as a model to others; (3) encourage and facilitate better working relationships in the university science and education community, as well as between universities and the private sector, to enhance program quality and supplement available resources; and (4) result in benefits that will likely transcend the project duration and USDA support.
The deadline is February 1, 2007.
For more info: http://www.csrees.usda.gov/funding/rfas/hep_challenge.html