Coupled with excessively high milk production, there is another factor aggravating cows' susceptibility to mastitis which has particular resonance with me as a breastfeeding mother. When my daughter was born, it didn't take long for me to learn that my comfort now relied on her frequent nursing. A little later, when I was admitted to hospital with an aggressive case of mastitis, I was repeatedly advised to keep breastfeeding regularly in order to alleviate the illness and help prevent its recurrence. Now with generally no more than two daily milkings, cows end up carrying around 20 liters in their udders. Again this is ten times more than they naturally would for their calves, who would feed five or six times a day. I cringe at the thought of a human equivalent. Not to mention that this also predisposes cows to lameness, as their voluminous udders splay their legs and put pressure on their outer claws.
So dairy cows have a hard time of producing milk. But that's not all. Because they are (artificially) re-impregnated while still lactating from their previous pregnancy, they spend seven months out of 12 simultaneously pregnant and producing huge quantities of milk! This leads John Webster, Emeritus Professor of Animal Husbandry at Bristol University, to describe the modern dairy cow as "a supreme example of an overworked mother," "exposed to more abnormal physiological demands than any other class of farm animal." It is little wonder that, despite their natural lifespan of 20 years, today's dairy cows are typically worn out, and therefore culled, by their third lactation.