Researchers Aim To Decode Mitochondrial DNA For Efficient Cattle Growth

Jessica Petersen (center), associate professor of animal science, and graduate students Mackenzie Batt (left) and Lauren Seier (right) are part of the research team.
Jessica Petersen (center), associate professor of animal science, and graduate students Mackenzie Batt (left) and Lauren Seier (right) are part of the research team.
(Craig Chandler | UNL Communication and Marketing)

To further understand the links between genetics and cattle growth efficiency, University of Nebraska-Lincoln researchers are focusing on cattle’s mitochondria—cell components whose biochemical activity produces most of the body’s energy for cell function, says a recent release.

While a variety of genetic data is already used by cattle breeders, information from the mitochondrial genome of an animal has been largely ignored, notes the release. 

This federally funded study will aim to determine how variation in cattle’s mitochondrial genomes affects overall efficiency in animal growth.

“Information on mitochondrial genotype will serve as a new tool for the selection of the most energy-efficient cows,” says Jessica Petersen, associate professor of animal science. Those cows, in turn, “will produce calves with the same desirable mitochondrial genotype.”

The researchers also noted that an increase in feed efficiency by just 1% would save the U.S. cattle sector more than $11 million per year.

The research team of faculty and graduate students including Jessica Petersen, associate professor of animal science; Dustin Yates, associate professor of animal science; Kristi Montooth, Susan J. Rosowski Professor of biological sciences; and graduate students Mackenzie Batt and Lauren Seier, have received a three-year, $650,000 research grant through the USDA.

“This project benefits the feedlot sector, where efficiency of growth is of critical importance, as well as cow-calf operations, where feed represents the greatest expense for each cow,” the team explained in the grant application.

The release notes that breeding has primarily been focused on selecting the best bulls and their genetic characteristics. However, this project finds the benefits in also understanding key genomic information from cows as mitochondrial DNA is inherited exclusively from the mother.

Cows, not bulls, pass on this mitochondria that’s so important for energy production, Petersen notes. “I think we’re missing an opportunity to select for better animals,” she says in the release.

The animal’s mitochondrial genomic data will be gathered through commercial genotyping of cattle, without much additional expense, and might be the key to opening additional opportunities for improved breeding.

The three-year project will include analyzing genomic data using skeletal muscle samples from approximately 1,500 steers from the university’s West Central Research, Extension and Education Center in North Platte and the Eastern Nebraska Research, Extension and Education Center near Mead, the release says.

This also provides an advantage, Petersen says, as cattle at the university “all have a genetic sample that’s taken when they’re born or when they’re received. So we’re already doing some genetic analyses of these animals. When they go through a feedlot, many have individual intake measures showing exactly how much they eat. We can then track how much weight they gained to get measures of efficiency.”

The study will also draw lessons from another relevant genomic study, within UNL’s Institute of Agriculture and Natural resources—a genomic analyses, or assay, on fruit flies by Kristi Montooth, professor in biological sciences.

Petersen explains that the team is taking what Montooth has learned and are applying it to beef cattle. 

“That is a little bit of a challenge. When they do a fruit fly assay, they grind up the whole fruit fly, and they can study it.” In this cattle-focused study, by contrast, “We’re studying with a little piece of muscle, and we’re actually finding we have to dilute our sample down quite a bit, because mitochondrion in muscle of cattle are very active,” she adds.

Following the study, the next step will be to determine how the mitochondrial genome interacts with proteins within the nuclear genome located inside cattle cells, Petersen explains in release, which will provide a whole other tool in selection of animals that have those better symbiotic genomes.

 

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