There is no reason to worry about the trans fatty acids of dairy origin. Even when consumed in quantities far above quantities that are normally consumed in the traditional diet, dairy trans fatty acids do not have any negative effect on health. Only an excess of trans fatty acids of industrial origin (in particular present in certain vegetable fats that are partially hydrogenated or in products that contain these fats*) can pose problems.
* Partial hydrogenation of vegetable fats and deodorisation of oils at very high temperatures could generate trans fatty acids. You can find trans fatty acids in products that are manufactured with these fats (e.g. biscuits, pastry, prepared food).
