Metabolism professor wants to help environment and dairy producers

Sebastian Arriola Apelo, a UW-Madison assistant professor of metabolism, wants to help the environment and dairy producers by improving how cows use nitrogen.

The utilization of dietary nitrogen by dairy cows is quite low — about 25 percent, Apelo says. The remaining nitrogen is excreted in urine and feces, essentially wasted.

This means dairy producers and water systems surrounding the farm are being harmed.

“Organic forms of nitrogen are very harmful for the environment,” Apelo told “It can leak to undersurface water or coastal waters and increase bacterial populations, and decrease oxygen content in those ecosystems.”

That process leads to reduced biodiversity, he says, as elevated nitrogen levels can cause some organisms to overgrow and crowd out others.

“It’s also harmful for air quality,” he said. “So it’s a general concern.”

He says dairy producers are among the main sources of harmful environmental nitrogen, and as environmental concerns increase, “we have to try to play ahead.”

Lactating dairy cows are expensive to study in the lab, he notes, so he and fellow researchers use what he calls a “scaffolding system” for trying out new approaches for improving nitrogen use, like genetic manipulation or certain medications.

Gene editing allows Apelo and colleagues to delete genes or increase their expression, and then see the corresponding response in milk protein production. Since the lactating cows are so valuable, this process of gene editing starts with established cow cell lines.

“We try it first in vitro, then we have to try to develop further concepts using a mouse as a model, and then we try to prove the concept in the lactating cows,” he said.

Apelo teaches these concepts both to undergraduates and to graduate students in the department. He says the school has nearly 80 lactating cows on hand purely for research, though the milk they produce is sold as well.

“Once we understand this system better, we can use nutritional approaches that are similar to the approaches we would recommend in the future to the dairy producer, in the cows that we have across the street,” he said. “The students can learn from those lactating cows.”

He says this experimental work could lead to some improvements in the industry, “maybe not in the short-term, but in the mid-term, to be fair.”

“We hope we will be able to do recommendations to the dairy producers,” he said. “They should be able to decrease the protein level in the diet, and supplement it with specific nutrients that are going to allow them to maintain the level of production.”

–By Alex Moe