The press release from the University of Manitoba’s National Centre for Livestock and the Environment last week spoke volumes.
Unfortunately, it said very little about science. It said a lot about sensationalism and just how politicized science has become.
“WHEN IT COMES TO FEEDING COWS, GRASS IS NOT GREENER – GRAIN IS,” the boldface, capitalized headline screams. “Major study defies myth that grass-fed cattle better for environment than grain-fed cattle; U. S. implements findings.”
The release goes on to tell us: “…contrary to popular belief, ruminants that are fed grain actually produce less methane and ultimately do less damage to the environment than cattle that eat grass. Animal scientist Dr. Ermias Kebreab decided to take a closer look at the common belief that grass is the greener, cleaner ‘crop,’ by comparing how much methane is exhaled by cows with a grain diet with ones with a grass diet.”
According to the release, he “discovered” that cattle on grass produce more methane than cattle fed grain. “The current belief is that grass is less of a contributor to global warming because grass is a less energy-intensive crop, explains Dr. Kebreab, whose findings were published last month in the Journal of Animal Science. “We found that this is not the case. In fact, not only do grass-fed cattle emit more methane gas and CO2, but they produce less milk and red meat than grain-fed cattle do.”
No eureka factor there.
It’s widely acknowledged that methane production from ruminant digestive processes is a major source of methane production.
Likewise, that high-fibre, low-energy diets cause more gas and have a lower feed efficiency is neither new or surprising. High-fibre diets have much the same effect on humans.
So did Kebreab really set out to prove one type of feed is better or “greener” than another? Actually – no.
Kebreab’s work, as published in the scientific article cited, studies the usefulness of mathematical models for estimating and measuring the amount of methane, one of several greenhouse gases, emitted by belching bovines.
His work compares the accuracy of several models, against the measurements used by the Intergovernmental Panel of Climate Change and actual emissions from cattle on different types of feed.
He found some models are better than others and that national inventory estimates would be more accurate if they were diet specific.
Presumably, the pre-existing knowledge on the effect different diets have on bovine methane production was useful groundtruthing for these mathematical modelling efforts. With better measures, scientists can study how to influence the output through dietary and management changes.
The “findings” implemented by the U. S. Environmental Protection Agency, relate to the application of mathematical models for measurement – not whether cattle should eat grain or grass – as the release implies.
In an interview, Kebreab readily acknowledges the amount of methane produced by cows is only one part of the greenhouse gas equation. Work is still in its infancy on whole-cycle analysis involving all greenhouse gases lost into the atmosphere due to factors such as inefficient fertilizer applications in grain production, or the fuel used to produce the grain, haul it to the cattle and haul away the manure from feedlots.
Concluding, as this release suggests – and the ensuing published reports in the mainstream media reported as fact – that grain-fed beef is better for the environment is not only misleading, it damages the credibility of the institution behind it.
Does NCLE exist to better our understanding of livestock’s interaction with the environment or to defend conventional agriculture?
Science shouldn’t be about taking sides or promoting one system of production over another.
It is about providing quantifiable context with which to support informed decision-making. And it is an evolving process. If there is one sure thing about how much we know today, it is that we will know more tomorrow.
Yet the practice of science has increasingly become polarized between two world views. One assumes that if we understand how things work, we can do a better job manipulating and controlling nature towards humans’ higher purposes.
The other operates from a basic premise that human activity tends to throw the natural balance of things out of whack. It aims to understand how things work so that human activity can operate within a more balanced and natural framework.
No parent who has experienced the miracle of antibiotics on a sick child would suggest we never interfere with nature. By the same token, there’s a lot to be said economically, environmentally and socially for exploring agricultural production systems that mimic the natural ecosystem – including forage-based livestock.
There’s need for both. Hopefully NCLE’s science does a better job reflecting that than its publicity stunts. [email protected]