The basic way that a monopoly harms consumers is by restricting output in order to send prices skyrocketing. Imagine when De Beers controlled almost all of the world's diamonds -- if prices were to fall unexpectedly, they'd simply choke off the supply. With fewer diamonds available, consumers will fight more intensely over them and so drive up the price. By creating an artificial shortage, De Beers makes consumers pay higher prices just so it doesn't bring in less money.
Unlike De Beers stuffing diamonds in their sock drawer, though, dairy farmers would have to pay huge costs to maintain cows that they'd taken out of milk production. So they just get rid of them altogether (from this WSJ article)
[L]ow prices have forced farmers to sell dairy cows through an industry program called Cooperatives Working Together. Member farms contribute money to the program, which purchases cows and slaughters them. So far this year, the number of working dairy cows in the U.S. has fallen by 170,000 to 9.2 million, says industry expert Jerry Dryer.
There you have it. Right in the pages of the newspaper with the widest U.S. circulation, we have an open-and-shut case of a group colluding to restrict its output in order to push prices back up to where they'd like them to be. For god's sake, they don't even break the law behind closed doors -- they've established the anti-competitive Cooperatives Working Together in plain view!
Of course, since they're farmers, they're not "gouging consumers" or "breaking the law" but merely struggling to preserve their endangered habitat. You can imagine the reaction if McDonalds and Starbucks saw their prices dropping due to the coffee war competition and agreed to destroy fully 2% of their coffee output so that they could charge higher prices for the remainder. Ditto if Wal-Mart and Target colluded. Actually, the elites would give Target a pass because they bring edgy designer junk to those who could otherwise only afford tacky crap. *
With most layers of government strapped for cash, the best policy response here is to shutter the DoJ's Antitrust division and have these glorified hall monitor pansies go do something useful.
* BTW, looks like the word "edgy" isn't so edgy anymore. One last slang-tastic paroxysm from the euphoric culture before it tumbled over like a drunk into a sewer.