Can pigs understand art? Mill's Utilitarianism

By the definitions laid out in the theory of Utilitarianism by Mill, content (as opposed to happy) is when a being has achieved all the desire they could want (a desire threshold, if you would). A swine is happy because they can't want for more than slop and mud. If a human had maximized pleasure and minimized pain, they would be as content as the swine. As of now, it seems no (or almost no) humans have reached their desire threshold, and yet would not sacrifice their mental faculties to have achieved a lower threshold. Due to these precious mental faculties, however, the human as content as a swine (at full threshold) would have no appreciation for pleasure vs pain. Happiness would be less happy without unhappiness to relate it to. Mills even states this himself, saying that without excitement during which much pain is endured, one is using tranquility only as a vice, and calls not wanting peace after excitement because it is boring a "disease". Is it not then justifiable under util theory to bring people pain through excitement for the moral sake of increasing their overall happiness?

As an afterthought, just as both humans and pigs can find similar levels of pleasure in food (but without filling similar percentages of their threshold), but pigs can't see beauty in art whereas humans can, is it possible that we could as blind to some great way of thinking as pigs are to our level of cognition? Humans have proven to be fallible, and it is not unfathomable to imagine a creature beyond our capabilities, such as an alien or a "better" or more evolved human. There could be more we are missing, but could we ever see it? Could a pig ever comprehend art?