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Industry: 1. Back-to-nature: 1. And we’re even January 22, 2010

Posted by Angelique in Global warming.
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[Hypothetical debate between technophiliac conventional industrial dairy farmer (Mack) and back-to-nature ex-hippie independent dairy farmer (Meadow) on the most climate-friendly way to raise dairy cattle.]

Meadow: the fact is, cows that eat grass burp and fart less than cows that are forced to eat grain, like your feedlot cattle. So, they release less climate-destroying methane into the air. We need to go back to feeding cows what they were designed to eat: grass.

Mack: Maybe if you hadn’t smoked so much of your cherished grass in the 60s you’d still be able to do math. Your dainty little cows might emit less methane per cow than mine; but when you take into account how little milk each of them produces, it’s not such a bargain. My cows produce so much more milk than yours that it more than outweighs the extra gas they pass. The fact is, my modern dairy machine emits less methane per gallon of milk produced than your old-school farm.

Meadow: What you people never take into account when you trot out this tired line are the greenhouse gas emissions associated with making the grain that your cows eat to become so super-productive. What about the emissions associated with all the fertilizing, tilling, processing and transporting of the grain to your “modern dairy machine?”

Mack: Yeah yeah yeah, everyone knows that those emissions are peanuts compared to the actual animals’ emissions. Are you going to deny that concentrated feed, in the form of enriched grain, increases milk yield and decreases greenhouse gas emissions per gallon?

Meadow: Again, oversimplifying. OK, it is general knowledge that concentrated feed increases yield and reduces emissions (again, not including the emissions from manufacturing and transporting the concentrate). But that’s not the only thing you’re doing over there in your little shop of horrors. You’re also breeding cows for yield and nothing else, and that’s increasing emissions, even on a per-gallon of milk basis.

Mack: Bull. Breeding for higher yield means we can produce all the milk we need with fewer cows, which means a smaller herd and lower emissions, overall and per gallon of milk. Case closed.

Meadow. If only. The problem is, as you well know, that cows bred for high yield are less fertile and less healthy overall. That means you have to engineer a bigger herd because you know that a large proportion of it will be infertile (and therefore won’t produce milk) and will die young due to poor health. My naturally-raised beauties, however, are all happy and healthy down by our little red barn.

Mack: Well, we are always doing more research to maximize the combination of high yield and high fertility. Granted, we’re not there yet, but where are your numbers to show that reduced health and fertility is such a big problem that it outweighs our gargantuan milk yields?

[Cut. Where, indeed, are the numbers? Many quantitative studies of livestock’s greenhouse gas emissions, misleadingly cited by one side or the other in this debate, analyze only one gas (e.g., only methane, only nitrous oxide) or only one source (e.g., only farting, only manure). Many also discuss emissions per animal, but not per unit of output, or do not include the off-farm emissions associated with inputs like fertilizer or cattle feed. One excellent 2006 study,* however, quantifies all these factors for pastured dairy cattle, and concludes that we can minimize GHG emissions by feeding generous amounts of concentrate (grain) to cattle that are bred for medium- (not high-) yield. While this study only analyzes pastured dairy cattle, these strategies also apply to feedlot dairy cattle in the US. What does it mean? From a climate perspective, the conventional dairy industry gets kudos for feeding cows grain instead of just grass, but the back-to-nature folks are right that conventional breeding for high yields is bad news. Looks like each side has something to learn from the other.]

*Lovett et al, “A Systems Approach to Quantify Greenhouse Gas Fluxes from Pastoral Dairy Production as Affected by Management Regime,” Agricultural Systems 88 (2006): 156-179.

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