Beef production offers an ecological ‘hoof print’ | Jennifer M. Latzke


The proposed “Green New Deal” recently focused on livestock – a plan that would limit livestock production to some extent in an effort to reduce their greenhouse gas “hoof footprint”.

But recently published research quantifies the role cattle play in the natural carbon cycle and how they serve a recycling goal by turning raw materials into more valuable protein that humans can eat.

Newspaper photo by Kylene Scott.

Al Rotz is an Agricultural Engineer in the Agricultural Research Service of the United States Department of Agriculture and an Assistant Professor at Pennsylvania State University. Rotz and Sara Place, senior director of research on sustainable beef production at the National Cattlemen’s Beef Association, an entrepreneur from Beef Checkoff, co-authored the study titled “Environmental Footprints of Beef Cattle Production in the United States.” United “.

The study was a comprehensive life cycle assessment that aimed to quantify the sustainability of beef production in the United States, from pasture to plate. He took into account every detail of every step of the process, from the fossil fuels used to pump irrigation water to grow fodder, to the blue water used for feedlots, to the loss of nitrogen. responsive and more. The researchers took five years, examined the seven cattle-producing regions of the United States, and used data from more than 2,000 surveys and site visits to consider climate, soil, production practices and other variables. All of this information has been researched so that the industry can establish a baseline from which to work in the future as it strives to improve sustainability.

Rotz and Place found that beef production in the United States is only responsible for 3.3 percent of greenhouse gas emissions, not the 14.5 percent that has been reported. In addition, American ranchers have avoided 2.3 gigatonnes of carbon emissions since 1975. This equates to about 1.9 billion passenger vehicles driven in a year. (The United States Transportation Bureau reported that in 2012 there were just over 2.5 million vehicles registered in total in the United States)

Livestock in the carbon cycle

To truly understand the power of the cow, you need to understand the natural carbon cycle and what it contributes to the carbon cycle.

“Cattle are part of the natural carbon cycle and it has been happening since the beginning of life on this planet,” Rotz said. “Carbon dioxide is fixed in plants as they grow, and they form carbohydrates that cattle eat and turn into meat or milk. And in the process, they excrete carbon in the form of feces, and they breathe in carbon dioxide and their belching is formed of methane. Methane is a powerful greenhouse gas, but this methane is not added to the cycle, it is just part of the already established cycle.

This is essential to understand, Rotz pointed out. The cow does not add new methane with its “belching” which will then turn into carbon dioxide in 12 years and absorbed by the plants, thus coming full circle.

Compare that to when we burn fossil fuels, which we took carbon out of the soil where it was sequestered out of the carbon cycle, Rotz explained. Burning fossil fuels introduces new carbon dioxide into the atmosphere, which must then be taken up by more plants in order not to contribute to the greenhouse effect.

Areas where we could improve

Well, when you factor in fossil fuel inputs, reactive nitrogen losses, and water use at different stages of a cow’s life cycle, there are certain points that represent more than methane emissions than to others. In general, when cattle graze forages, such as in the cow-calf or feeder phase, total methane emissions are higher than when cattle finish feeding in a feedlot, Rotz said.

In general, in the life cycle of cattle, the cow-calf phase probably accounts for 65 to 70 percent of greenhouse gas emissions, followed by the fattening phase at around 10 to 12 percent, the remainder being found in the feedlot or finishing phase. .

“From a greenhouse gas perspective, the amount of fossil fuel used in the production of beef cattle is not a major contributor to overall greenhouse gases in a cow’s life cycle,” Rotz said. “Still, from a fuel economy perspective, I think we can do better.”

Even though beef production represents less than 1 percent of the total fossil fuel consumed nationally, this is still a point that could be improved in the system. And the good news is that by being more careful with fuel consumption, ranchers also improve their bottom line.

There is also something to be said about taking into account the genetics of cattle which earn faster and therefore go through their life cycle faster, Rotz said. Less time spent on feed means less money spent on feed and less methane emissions overall.

Part of the history of beef production that is overlooked by people outside the industry is how cattle take raw materials that humans cannot consume and convert them into high-value protein.

Tryon Wickersham is an associate professor of animal nutrition at Texas A&M University, and his research has quantified the extent to which cattle “recycle” low-value nutrient sources in a glass of milk or a steak on a plate.

“Ruminants have been around for a very long time,” Wickersham said. “The buffaloes were already there before we arrived in 1492 and we have cattle now. When a cow belches methane, it is energy that has not been converted into meat or milk, and so from a beef farmer’s point of view, anything we can do to reduce its methane emissions improve the performance of a cow.

We know that methane production is higher in cattle grazing forages than in grain or grain by-products in the feedlot, Wickersham said. But, from an upcycling point of view, the grazing part of the life cycle is actually more efficient at recycling protein quality for human consumption, because it uses more grass than a human can consume. . It converts vegetable proteins with fewer digestible essential amino acids into animal proteins that provide more of what the human diet needs. In the United States, 90 percent of the food consumed throughout the life of grain-fed cattle is inedible for humans, from the 800 million acres of pasture grazed by cattle to the byproducts of biofuels and food industries such as distillers’ grains and wheat scraps that would otherwise go to landfill.

And yet America’s feedlots do a very good job of converting food into protein on the plate, he added, approaching almost a 1: 1 ratio for every unit of amino acid intake. high quality in the feedlot steer, there is almost a unit of high quality protein produced for human consumption. It’s even better than monogastrics like chickens or pigs that are fed a soy diet. It may seem counterintuitive to redirect edible proteins like wheat, corn or soybeans to livestock feed, but research shows that processing ruminants dramatically improves the quality of protein delivered to the plate.

Further research is underway to determine how much of the beef production system we can improve both greenhouse gas emissions and protein recycling that cattle do for humans. But one thing is for sure, said Wickersham, that anything we offer must be linked to the economic reality of ranchers.

“I think there are lots of opportunities to develop technology that helps cattle herds improve,” he said. Whether it’s studying how to reduce mortality losses in the cow-calf phase, or studying feed additives that can help cattle produce less methane with every bite, or even discovering indicators of cheaper performance to help breeders improve their herds for better recycling and reduced methane production — there is still a lot of research to be done.

“When we do something to improve our efficiency, we reduce our costs,” Wickersham said. “And it allows more people to access the food product. If you take away food technology, you’re really removing options for a lot of people who don’t have the disposable income to spend on niche beef products.

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