Regarding trans fat in meat and dairy: Technically, there shouldn't be any trans fat in meat and dairy. However, if the meat has been cooked in margarine or deep fried in partially hydrogenated vegetable oil, then it has trans fat. Also, a mother who eats french fries and donuts during pregnancy will have trans fat in her breast milk. Theoretically, dairy could also have trans fat if the cows were fed it somehow.

However, meat and dairy are not the things to worry about when it comes to trans fat. Trans fats do not naturally occur in meat and dairy. The real culprit in the trans fat scenario is carbohydrates that have been processed i.e. junk foods and some oils. Cut these out and you've cut out most of the trans fat in your diet. As far as the trans fat and oil connection, canola and olive oil appear to be the best.