Given the input sentence, please extract the subject and object containing a certain relation in the sentence according to the following relation types, in the format of "relation1: word1, word2; relation2: word3, word4". Relations include: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

That's a potentially big problem, because the US and Mexico are unlikely to open up their agricultural markets to Aussie and Kiwi farmers unless American dairy farmers can sell more dairy and poultry into Canada.

Answer: product_or_material_produced: dairy farmers, dairy