regional variations in cow populations

If you have journeyed cross country and are prone to cow observation, you might have noticed that different kinds of cows show up in different regions. In my experience, most of the cows you will encounter in the northeastern part of the U.S. are Holsteins (those black on white spotted cows), while midwestern cows are generally of the all black (Angus) and all brown (American Shorthorn) persuasion.

There is an explanation for this geographical variation in cattle populations!

First of all, some basic information about cattle:

• Holsteins are milk cows. If you see one of these cows (and they will likely be cows and not bulls), think cheese and ice cream.
• Angus and American Shorthorn are beef cattle (although I think there might be a strain of Shorthorn specialized for milk production). To farmers, these are, essentially, walking hamburgers.
• In order to produce milk, milk cows require access to green feed all year long. That is, they can't be fed on hay, but require food with some active chlorophyll. Beef cattle can be fed on hay without any loss of productivity.

In the northeastern portion of the United States it is wet all year long. This (presumably along with some regional variation in local grasses) results in year-long green grass. Since there is actually a demand for milk products, cattle farmers in the northeast raise Holsteins, taking advantage of the presence of green feed. In the midwest it is often hot and dry in the summer, and cool and dry in the winter. Here the native grasses brown, forming pastures of standing hay. As you might expect, this is the land of beef cattle, and you are unlikely to come across a large herd of Holsteins among the Angus and Shorthorns.

So now you know!

Note that this explanation can be used predictively. I've not been to Texas, but I suspect that, like the midwest, it turns brown in the summer. How do I know? Easy, Texas Longhorns are beef cattle. I would also guess that the grass stays green year-round in Wisconsin. Judging from their cheese output, they seem to have a thriving dairy industry.