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Cattle Genetics may impact carbon emissions

By Denice Rackley for Tri-State Livestock News

For decades the beef industry has been researching the role genetics play in cattle performance. That research has enabled beef producers to utilize expected progeny differences (EPDs), leveraging heritable traits to produce animals that excel in their particular environment and management style. New cooperative research between the American Hereford Association and Colorado State University (CSU) is underway to identify genetic components associated with the environmental sustainability of beef cattle.

Some people believe that ruminants are negatively impacting the environment and contributing to the warming of the planet due to their production of methane. Methane (CH4) is produced by the rumen microbes as fibrous plant material is digested. The Environmental Protection Agency estimates that 11 percent of U.S. greenhouse gas (GHG) emissions come from the agriculture sector. According to Frank Mitloehner, UC Davis professor and air quality specialist, cattle and other ruminants account for 4 percent of our GHG emissions. Methane is of significant concern because it’s 25 times more potent than carbon dioxide (CO2) at trapping heat in the atmosphere.

Olsen Ranches. Courtesy photo
Olsen Ranches. Courtesy photo

“This industry has done a remarkable job of producing more beef with fewer cows, but we’re going to continue to be asked to do more with less,” according to Jack Ward, Executive Vice President of the American Hereford Association (AHA). “Over time, we’ve documented the value of Hereford genetics in commercial cow herds in terms of fertility, longevity, feed efficiency and other traits associated with production efficiency. All of those things, as we understand currently, are going to have a positive effect in terms of sustainability as we move forward in the industry.”



Identifying genetics related to environmental sustainability

Specifically, AHA-CSU research aims to enhance understanding of the genetic differences in seedstock relative to enteric methane production and nitrogen excretion.



Are some cattle genetically predisposed to use carbon and nitrogen in feedstuffs to build body and muscle mass rather than exhale or excrete nitrogen and methane? Can we identify those genetics that support environmental sustainability in cattle? These are the questions researchers are investigating.

In a small study at CSU prior to the pandemic, Scott Speidel Ph.D. specializing in animal science, breeding and genetics at CSU, explained that preliminary data showed nitrogen excretion has a genetic link. He believes methane emission will also reveal a genetic component that will lead to the development of selection tools for reducing beef’s carbon footprint.

Understanding the genetic differences in seedstock relative to enteric methane production and nitrogen excretion and identifying those genetics that reduce greenhouse gas emissions without sacrificing animal productivity is the task before Kim Stackhouse-Lawson, director of CSU’s AgNext and other CSU researchers in this study.

Snack machines

Greenhouse gas emissions from cattle have been studied in previous research at CSU Stackhouse-Lawson explains. In the 80s, methane emissions were recorded in a chamber, she recounts. Recent advances in technology enable research within the cattle’s natural environment, which will give real-world data since the cattle will be behaving normally.

Feedlot cattle at the Olsen Ranches in Harrisburg, Nebraska, will be studied using bait stations within methane collectors. Portable bait stations, or snack machines, dispense bait, typically alfalfa pellets, in a hopper. When eating a treat, the animal sticks their head in the hopper. The oxygen, hydrogen, carbon dioxide, and methane breathed out by the animal are measured, relaying information about the animal’s physiology and what is happening within the digestive system.

Cattle, in general, lose about 75 percent of methane through their lungs when exhaling, 15 – 20 percent by belching, and the rest as flatulence and in manure Stackhouse-Lawson explains. Therefore, measuring the amount of methane that cattle exhale will give a good indication of the amount of methane they are putting back into the environment. Most cattle will go to the “snack machine” two to four times a day; it takes 30 days of readings to accumulate baseline data on each animal, she notes. 

In addition to measuring methane, this study is also monitoring water intake, nitrogen, and ammonia levels in manure.

Combining data

With about 15 different sire groups at the Olsen Ranches, the new data, when added to the information amassed through AHA’s Whole Herd Total Performance Records (TPR™) and the National Reference Sire Program, including feed intake and efficiency records, will provide detailed information that can be used in an EPD and eventually moved toward a selection index for environmental sustainability.

Sustainability and methane

Sustainability hinges on three pillars – social, environmental, and economical, says Stackhouse-Lawson. Without all three, sustainability is not possible. Interestingly she points out that due to the ongoing emphasis on feed efficiency, cattle that naturally produce less methane might already have been selected for. Producing methane, as a result of digestion, translates to a loss of energy, she points out. When plant materials are converted into energy by cattle, multiple studies have shown 2 – 12 percent of the feed energy is lost to methane emissions. With reduced methane production more energy is retained by the individual and utilized for growth, reproduction, milk production, etc.

Stackhouse-Lawson also says that methane produced by cattle is part of the natural or biogenic carbon cycle unlike methane and carbon dioxide produced by manufacturing and burning fossil fuels and other manmade activity. Plants take carbon from the air during photosynthesis turning it into energy for growth. Cattle consume the plant and release some of the carbon back into the air as methane that will cycle back into plants. Biogenic methane can stay in the environment for 10 to 12 years, unlike the additional CO2 that is added to the atmosphere with the burning of fossil fuels that remain for a thousand years. This significant difference is rarely brought to light.