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Comment by GlenTheMachine | Hacker News Reader

I'm not referring to mono cropping for animal feed. I'm referring to mono cropping for human consumption. A large fraction of the calories in your diet likely comes from corn, if you live in the US and get your food from the grocery store.

There used to be hundreds, maybe thousands of varieties of corn grown regularly in the US. There aren't any more. It's hard to tell how many corn varieties that are grown commercially in relevant quantities, but it's certainly less than fifty, and maybe less than twenty.

Less genetic diversity means less robustness to changing pathogens and climate.

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I generally agree with you but FWIW most of the corn (90%+) grown in the US goes into animal feed, e.g. for cows.

Which is of course its own little tragedy, considering you get 1 calorie of cow for every 12 calories of corn.

FWIW, that (sorta) still counts as "comes from corn".

That's a good point, thanks.

This was true several decades ago, but now about 1/3 of it used to manufacture ethanol due to the US transition to gasoline having 10% ethanol content. It is still very much true that far more of it goes to animal feed than food for humans though.

https://afdc.energy.gov/data/10339

Note that a byproduct of ethanol production is distillers grains[1] which are used as an animal feed. Also worth noting that the percentage of corn used for direct human consumption has stayed at around 10-20% before, during, and after the ramp up in ethanol production:

Ethanol + animal feed chart: https://i.imgur.com/1QqPTje.png

Ethanol production chart: https://i.imgur.com/3wwzkIi.png

[1] https://en.wikipedia.org/wiki/Distillers_grains

Maybe 1 calorie of cow per 12 of corn, but dairy cows are much more efficient than that:

Cow eats 40.57 MCAl/day [1]

Produces 45.5 KGS of milk [1]

Milk 610 kcal/liter

Energy of cows milk per day 27.755 MCAL

Cow milk efficiency 68%

This feels high as a gut reaction, maybe calculation is missing energy to grow the cow. Still it shows how efficient they are!

Would love a source for your cow meat efficiency numbers, I'm currently exploring efficiency of fermentation methods to produce meat alternatives and that would be a helpful data point.

Source: [1] http://www.milkproduction.com/Library/Scientific-articles/Nu...

Don't underestimate the contribution of the "energy to grow the cow". Dairy cows don't start producing until they're 2 years old and are typically only kept around until age 5 or 6. That's a full third (or more) of their lives with no output whatsoever.

My god that's brilliant. Cows more efficient than the combustion engine?

In practice having more different varieties of corn didn't really give us more protection against pests or pathogens.

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