The cows are a (bad) metaphor for the means of production, obviously. The metaphor sneakily puts you in the shoes of a capitalist and, whoa, it turns out capitalism is good when you are one of the few it benefits.
I can't believe I was once taught this bullshit in school.
**DAS COWPITAL ** You are a cow. Everyday, your milk is stolen violently by the capitalist farmer who owns you. You make the milk, but you eat the farmer's grass on the farmer's land and use the farmer's milking stales, so he is entitled to your product, and only has to give you enough food (wages) to survive. The same is broadly true of the farmhands who feed you, clean the stables and milk you. You can't go to the wild, because all of the land that grows your food was enclosed by capitalist farmers in the 16th century, doing something called primitive accumulation. So you have to grin and bear it. The farmer, though, has many cows like you, and eventually he'll make so much milk that he can fulfill his own milky needs, sell it to pay his farmhands, feed his cows and maintain his farm, but still have money left over. But he doesn't want his "work" to be in vain, so he'll live more lavishly and buy more cows. Eventually, he'll get so rich that him and his farmer friends will want someone else to do their work for them, so they'll set up a hedge fund with employees to invest their money for them. They're now alienated from the suffering their profit-seeking causes, and so are more able to dismiss it, and the hedge fund employees have strict orders to maximise profits. So milky profit margins have to keep going up. In addition to this, other groups of farmers have done the same, and all the farms in the world are now competing for profit, and consumers will buy the cheapest products, so the farms will lower their prices. Others will do the same, and no one will be able to raise them again because then they'd lose market share. So the rate of profits will tend to fall. You might say there'll be a tendency of the rate of profits to fall. So profit margins are falling and the hedge fund employees are supposed to grow them. So they'll look at the farms they run, and conclude the only ways to expand profit margins are to reduce costs and raise prices. Reducing costs means either lowering wages (of the farmhands or the feed they give you) or making things cheaper (eg. using cheaper feed, cheaper milking equipment). Of course, they could innovate and raise prices without causing suffering for the consumer, employee or cow, but this takes time and is expensive, so probably not an option most of the time. Eventually, the proledairyat will suffer so much from falling wages, poorer conditions and rising rents they will rise up and kill the farmers.