MIDWAY : Eco-benefits of rat’s milk

Why do we not try drinking rat’s milk, cat’s milk or dog’s milk?” wondered Heather Mills this week, articulating the thoughts of a nation quite frankly bored to tears by the milk of ruminants. Mills was at a photocall in aid of a new campaign by Viva (Vegetarians’ International Voice for Animals) which is, in the wake of a UN report that found that the livestock industry generates more greenhouse gas emissions than transport, urging us all to go vegan.

It is an important issue, but Mills’ comments left some big questions unanswered: how does one milk a rat? Would rodent milk make a decent latte? Could we ever see rat’s milk cheese? And perhaps most pressingly, hasn’t she ever seen the rat’s milk episode of the Simpsons, in which local mafia don Fat Tony plans to supply rat’s milk to the school cafeteria? “I would imagine she was thinking that any mammal produces milk,” says Juliet Harbutt, chairman of the British Cheese Awards.

“However, if one would like to envisage, just for a moment, the difficulty of actually milking a rat, perhaps it would provide the answer. It would probably be easier to milk a whale. They’re bigger.” Theoretically one could milk a pig. “Though again,” she adds, “milking a pig could only be described as a challenge.”

Sadly, pig’s milk, though drinkable, would not be suitable for making cheese because its percentage of protein is too low — indeed this is the problem with a lot of mammalian milk; human milk, for example, has a protein content of just 1.4% compared with 8.4% in reindeer milk. Rat’s milk, however, is high in both protein (8%) and fat (14%, compared with that of a shorthorn cow, which is 3.8%), so in theory would make not only fine cheese but a hearty latte (or should that be ratte?), for which most coffee shops, including Starbucks, use whole milk.

But would it be more environmentally friendly? Cows produce 31kg of milk a day, while rats muster just 0.046kg a day. So we would need approximately 674 rats to meet a single cow’s milk production. Cows famously produce around 500 litres of methane a day, compared to around 2.256ml per rat. So even 674 rats only produce 1.5 litres of methane. Damned right, Mills, bring on the rat dairies!