Quote of the Day
The good thing about science is that it is true whether or not you believe in it.
— Neil deGrasse Tyson
Many of my blog posts are motivated by lunch-time conversations with our engineering staff. During lunch a few days ago, several of us were sitting around a table and trying to estimate the number of cows in the US, their daily milk production, and how much they eat per day – it might sound boring, but actually was pretty interesting.
After we finished doing our estimates, I did a bit of web searching to determine what the truth was. Our estimates turned out to be fairly accurate, but what shocked me was how the number of cows in the US has been dropping while milk production per cow has been increasing. This is an amazing tale of productivity improvement. Consider the following figure from this source.
The population of cows in the US has been declining since 1944, while milk production per cow has increased to nearly 10,000 kg per cow, which is about 2550 gallons per cow per year or ~7 gallons per day. I show the conversion calculations below.
The productivity variation between cows is substantial. The record milk producer is a Wisconsin cow that produced 8,295 gallons of milk in a single year – more than 3 times the average cow's annual milk production.
The improvement in the milk production per cow also comes with a reduction in the amount of food needed to produce each 100 pounds of milk, as shown in the following chart (source).
