Cows, Growth Hormones, and Global Warming

Here's one for you, just in case you weren't confused enough about which foods you should eat. The diary industry is known for its use of recombinant bovine somatotropin (rbST), a protein hormone that boosts milk production. You may have noticed it on your pint of Ben & Jerry's Cherry Garcia: "No significant difference has been shown between milk derived from recombinant bovine growth hormone treated and non recombinant bovine growth hormone treated cows". Its use is controversial, as are its potential human impacts. The product has one seller: Monsanto. It is banned in Canada, and parts of Europe and New Zealand. Several FDA scientists were pressured to cow.pngleave or dismissed during the approval process in the United States. Monsanto sued an independent dairy over their use of a label that pledged not to use the hormone - and won (resulting in such labels mentioned above). Approximately 1/3 of the dairy cattle in the US are injected with rbST. Most recently, many grocers (including some big ones like Wal-Mart) have pledged not to sell rbST milk. Organic milk is the fatest growing sector in the organic food market.

So, here's the rub. A recent paper in the Proceedings of the US National Academy of Sciences looked at the environmental inputs of dairy production with and without the use of rBST. Their results complicate your life. Cow's methane-laden flatus is the source of ten percent of the global annual emissions of this greenhouse gas. From a diary farmer's perspective, using rbST improved individual cow production, with reductions in nutrient input and waste output per unit of milk produced. From a industry perspective, rbST reduced feedstuff and water use, cropland area, N and P excretion, greenhouse gas emissions, and fossil fuel use compared with an equivalent milk production from unsupplemented cows. It's a complicated world we live in.


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Nice article, noticed a typo though:

"Its use is controversial, as our its potential human imacts."

should be (I think):

"Its use is controversial, as are its potential human impacts."


I don't know very much about the subject so I'll only add a few observations. Half the authors have interests with Monsanto and Castañeda-Gutiérrez is with Nestlé. rbST is not the only way of reducing livestock emissions by any means. I'd be interested to see it compared with other techniques.

Of course the best way to cut down on livestock emissions is to cut down on livestock agriculture. But somehow I don't see that suggestion coming from any agricultural universities.

Consuming less milk does seem like a good option. Apparently, the government nutritional guides that call for 2-4 servings a day of dairy are driven more by powerful dairy organizations, and less by nutritional sense.

A good observation regarding the affiliations of the authors of the study, I noticed that as well. But it is important to remember that this was a peer-reviewed study published in a highly recognized journal. Which is very different that a non peer-reviewed study by those same authors. The reviewers and editors had not interest either way in terms of seeing the science published, and thus the science is most likely sound (as presented that is). It will be interesting to see the response of the scientific community from the study, which may reveal weaknesses, issues, etc.

By Josh Donlan (not verified) on 02 Jul 2008 #permalink

Josh: I'm not impugning the quality of the research. I have no reason to doubt that it is rigourous. It certainly looks ok.

However, in my experience, you only see what you're looking at, ie. rather than asking the questions "how do we reduce emissions from livestock", they've asked "does rbST reduce emissions from livestock".

Milan:Indeed. I very rarely drink milk or dairy, for environmental and ethical reasons.

I have my doubts about the validity of the whole cow-methane discussion. Cows recycle carbon fixed by plants. This is current carbon, i.e. carbon incorporated into the global ecosystem, not much new fossil carbon, I would think. The basic assumption of the discussion is that a reduction of the world's domestic cattle herd would cause a correlated decrease in methane production. I see no reason to think so. If there were no domestic cows to house the bacteria which produce the methane, it would simply come from bacteria somewhere else. However, it might be that more carbon would be released as CO2 than methane. I'd love to see a discussion of these questions by someone versed in microbiology and ecosystem ecology. I know enough to be dubious, but little more.

By Jim Thomerson (not verified) on 06 Jul 2008 #permalink

Jim does have a point, but it ignores all the other energy requirements of dairy (and other cow-based) agriculture. Producing fertilizer requires large amounts of natural gas, transporting all the inputs into agriculture uses various forms of fossil carbon, transporting the output require a similar use of fossil carbon, and the same applies to the vegetable crops that have to be grown for the cows to eat. And, as Jim mentions, methane is a much worse greenhouse gas per carbon atom than CO2 is--we'd be better off climate-change-wise if we just took all the feed that cows ate and burned it.

Yes, I did intentionally ignore the things Jason mentioned. When I was a child we had 12 acres which my Daddy farmed with a team. After a few years, we realized that we were largely raising feed for the team. We got rid of the team and turned the fields into pasture. Jason's points are well taken.

By Jim Thomerson (not verified) on 07 Jul 2008 #permalink

You could go further.
Seems to me I consume more whiteners than milk.
I didnt know I needed all those extra vitamins.
Tastes funny, too. Not like the stuff ya get outta cows.