The Right Ingredients

Jean Hall

When Jean Hall came to Oregon State in 1997 to teach small animal medicine and surgery, she thought of it as an opportunity to reconnect with her roots. She moved to a property north of Corvallis and started raising sheep, something that tied her to her childhood in southern Oregon.  

Raising sheep also tied her to a problem she had been familiar with when she was growing up on Oregon farmland: selenium deficiency and how it can affect animal health. Selenium is an essential micronutrient for animals as well as humans, and Oregon is a selenium-deficient state.

Hall, who had already spent time researching how nutrition affected immune function in dogs and cats, saw a niche she could fill in the problem of selenium deficiency in livestock. After going to school in Washington, and working in Boston and Colorado, it made her return to Oregon even more momentous.

“My goal was always to come back to Oregon,” she says. “The idea that the vet school was here was perfect. What I love about my job is the opportunity to do research and help the farmers. To give back to my upbringing and state. I feel a very strong allegiance to Oregon.”

Hall is a fifth generation Oregonian. She comes from a long line of farmers, and as a 4-Her she became aware of how animals can both flourish and suffer because of geography.

Although it wasn’t well understood at the time, Hall saw the effects of selenium deficiency while growing up on the family farm. Livestock would suffer from nutritional myopathy, a degenerative and potentially fatal disease in their heart and skeletal muscles.

Selenium deficiency came into play again when Hall moved to Corvallis. She started seeing her sheep exhibit signs of foot rot, a chronic disease that makes it more difficult for sheep to forage.

“We have wet soils, we have the right bacteria,” Hall says. “And if sheep get an injury then they get this disease. Their foot is kind of necrotic. And they limp. They can’t move around and eat well. And so they deteriorate in their body condition or get skinny.”  

The problem got Hall thinking. She had already been researching the effects of essential fatty acids on immunity in dogs and cats. She started to wonder if raising selenium levels in her sheep might have an effect on their immune systems, as well. Maybe, she thought, sheep might be able to fight foot rot and other diseases more effectively if they had more selenium in their diets.

To the uninitiated, this might seem like an easy fix. But too much of a good thing, like selenium, can be fatal to animals.

“This mineral has a narrow window. Most vitamins or minerals have a wide spectrum,” Hall says. “With selenium if you go to one end you’re deficient. If you go to the other you’re toxic. People are spooked about that. So they stay on the low end.”

Normally, Hall says, selenium is given to animals as a salt, in an injection, or in a slow-release bolus form. Animals use what they need, and excrete the rest. But a miscalculation in dosage can become toxic and possibly fatal for the animal.

She had a different idea: fertilize with selenium, and it gets incorporated into the proteins of the plants animals eat – namely in their hay. And then animals get it naturally.

“What we really end up mimicking is soils that have adequate selenium in them. Like in North Dakota, they have plenty of selenium in their soils. We’re just building that up in our product – the hay – that we feed to our animals,” Hall says.

It’s a different way of administering the mineral altogether, the lengthy name for it being “agronomic biofortification.” Instead of excreting excess selenium, animals instead store selenium in their tissue when the mineral is incorporated into their hay. It can act as a reservoir during leaner months, when forage isn’t as readily available for animals, or during periods of birthing or winter confinement.

Also, when selenium is given to animals via agronomic biofortification, toxicity is no longer a threat. The kind of plants the livestock eat will not accumulate enough selenium to be toxic to them. States like Arizona and Utah, Hall says, are environments where selenium accumulator plants grow – if animals eat too much of them, they could become sick.

In Oregon, however, Hall’s research suggests that the levels of selenium put into fertilizer and the plants that concentrate it are not harmful to livestock or otherwise present an environmental hazard.

So far Hall’s research has shown that dietary selenium can improve immune responses in livestock, specifically in animals suffering from foot rot. She’s hoping that fortified crops will soon catch on and be adopted by farmers throughout the state.

“When you can actually show that there are mechanisms for how a food additive or a supplement works, and that those mechanisms influence immune responses, then that’s exciting to me,” Hall says. “I am very much interested in what you can do nutritionally – for dogs, cats, sheep, dairy cattle, beef or humans. What you can do to improve the quality of life via what they eat.”