Radiolab – "The Resistance of a Cow"
April 17, 2026
Hosts: Latif Nasser, Simon Adler, Matt Kilty
Episode Overview
This episode of Radiolab dives into a bizarre and captivating mystery that began on a Danish dairy farm, where cows unexpectedly refused to drink water, instead turning to drinking each other's urine. What seemed like an isolated incident soon unraveled into a widespread phenomenon connecting farms in Denmark and the United States. The story weaves together investigative journalism around cow behavior, stray voltage, electricity’s history, and the ongoing debate around how modern electrical infrastructure may—or may not—be affecting livestock.
Key Discussion Points & Insights
1. The Mystery Begins: Cows Refusing Water
- Danish journalist Clara Grunel discovered an article about cows on Danish farms refusing to drink water, which piqued her curiosity ([02:24]).
- On visiting Gregers Christensen’s farm, Clara and her colleague witnessed cows refusing water but eagerly drinking urine straight from other cows ([04:50]).
- Gregers (farmer): “I don’t know what to do. I’m about to sell all of my cows. This is my life’s work.” ([03:53])
- Tests showed the water was clean, but the cows continued avoiding it unless it came from another source ([06:01]).
2. A Search for Answers: From Folk Explanations to Electricity
- Gregers consulted Gitte Gyde, a local “cow expert," who used rituals involving copper wires and a gold pendulum, and claimed a nearby power station (Viking Link) was emitting damaging energy ([07:51]).
- Gitte: “You’ll have to mail me my stuff because I’m never going back to that place ever again.” ([07:22])
- The theory: Electricity from the Viking Link station is somehow getting into the water and affecting the cows’ behavior ([08:37]).
3. Beyond Denmark: Cases in the U.S.
- Clara’s subsequent research revealed other farmers, both in Denmark and the U.S. (notably Jill Nelson in Minnesota), experienced similar phenomena: cows refused water and drank urine ([09:54]).
- Jill’s family farm, operating since 1884, noticed issues as early as 2008 ([10:01]).
- Jill Nelson: “They would walk over to a puddle of urine and drink that dry. I’ve never seen anything like it before.” ([10:39])
4. Stray Voltage: An Invisible Menace or Red Herring?
- The term “stray voltage”—unintended electricity leaking from power lines into farms via concrete, rebar, and water—becomes central ([11:00]).
- Many U.S. dairy farmers recount stray voltage cases, with some reporting devastating losses ([11:26], [12:50]):
- Larry Neubauer (electrician): “I would have to say probably close to over 4,000 to 5,000.” ([11:45])
- Jill Nelson: “My son’s favorite cow... she literally died right in front of me. When that happened, that was it. I couldn’t do it anymore.” ([12:58])
- Many U.S. dairy farmers recount stray voltage cases, with some reporting devastating losses ([11:26], [12:50]):
- Yet, some experts and officials begin to question whether stray voltage is truly responsible ([13:32]).
5. Context: The Electrification of America & Rural Resistance
- The episode investigates the history of electricity’s expansion, illuminating rural skepticism as power lines stretched across farmland ([16:38]).
- Insights from historians Richard Hirsch and David Nye frame the growth of electrification and resultant farmer unrest, especially during the 1970s power-line protests in Minnesota ([21:53]).
6. The Science: What Does Electricity Do to Cows?
- Efforts to scientifically test how much electricity it takes for a cow to feel or be harmed by stray voltage are recounted with input from Professor Doug Reinemann ([25:05]).
- Animal behavior and controlled studies at UW Madison found cows react to stray voltage at levels akin to the sensation of a 9-volt battery on a human tongue ([27:15]).
- Doug Reinemann: “Put a 9-volt battery on your tongue. That’s the sort of experience.” ([28:16])
- Animal behavior and controlled studies at UW Madison found cows react to stray voltage at levels akin to the sensation of a 9-volt battery on a human tongue ([27:15]).
- Regulatory thresholds were set based on these studies, but few farms ever reach those levels ([29:26]).
7. Alternate Explanations: Diet, Behavior, and Social Dynamics
- Veterinary experts like Dr. Don Sanders and Nigel Cook explain that mineral deficiencies (e.g., potassium) or social/dietary stress can drive cows to drink urine ([31:19], [32:42]).
- Dr. Don Sanders: “Cows being milked are more like high-performance athletes... If their diet is not perfectly dialed in, things go bad.” ([31:52])
- Cows are sensitive to barn design, social hierarchy, and overcrowding, all possibly resulting from the shift to larger, industrial-scale dairies ([34:14], [35:35]).
8. The Crux: What is the True Resistance of a Cow?
- The episode dissects the basis for “acceptable” levels of stray voltage, which hinges on knowing the electrical resistance of a cow ([39:38]).
- Standard: 500 ohms. But recent field measurements suggest it could be closer to 200 ohms in modern, wet, group barns—making cows potentially more vulnerable ([46:48]):
- Larry Neubauer: “It's nowhere near 500 ohms.” ([43:17])
- If resistance is lower, cows could be exposed to twice the threshold current even when following regulations ([47:14]).
- Data supporting a 200-ohm resistance exists but remains unpublished/lost; accepted standards remain at 500 ohms ([48:59]).
- Standard: 500 ohms. But recent field measurements suggest it could be closer to 200 ohms in modern, wet, group barns—making cows potentially more vulnerable ([46:48]):
9. The Human Toll and Unresolved Debate
- The battle between farmers’ lived experiences and experts’ interpretations continues, with policy implications for animal welfare and infrastructure design:
- Some farmers (like Jill) found relief only after electrical repairs were made, though cause and effect remain hotly debated ([50:32]).
- Jill Nelson: “Eventually they came out, made a bunch of changes... Things went back to normal.” ([50:37])
- Others, like Gregers, gave up dairy farming altogether ([49:57]):
- Clara Grunel: “He sold the cows... Now a potato farmer... cows are thriving on another farm.” ([49:57], [50:03])
- Some farmers (like Jill) found relief only after electrical repairs were made, though cause and effect remain hotly debated ([50:32]).
10. Looking Ahead: Electrification and Future Risks
- With ever-increasing electrification (AI data centers, public transit), the episode notes stray voltage—and the debate around it—may become more pressing ([51:42]).
Notable Quotes & Memorable Moments
-
On first witnessing the cows:
- “The cows start drinking each other's piss. Like, the moment a cow starts peeing, all these other cows will immediately run over and turn their head to sort of like catch the piss in the air.”
— Latif Nasser ([05:01])
- “The cows start drinking each other's piss. Like, the moment a cow starts peeing, all these other cows will immediately run over and turn their head to sort of like catch the piss in the air.”
-
On being desperate for answers:
- “You'll have to mail me my stuff because I'm never going back to that place ever again.”
— Gitte Gyde ([07:22])
- “You'll have to mail me my stuff because I'm never going back to that place ever again.”
-
On the emotional toll:
- “My son's favorite cow... she literally died right in front of me. When that happened, that was it. I knew that I couldn't do it anymore.”
— Jill Nelson ([12:58])
- “My son's favorite cow... she literally died right in front of me. When that happened, that was it. I knew that I couldn't do it anymore.”
-
On scientific standards:
- “So they come up with this number. 500. This is known in the world. The 500 ohm cow.”
— Matt Kilty ([43:02])
- “So they come up with this number. 500. This is known in the world. The 500 ohm cow.”
-
On how new farming methods complicate things:
- “Somebody comes and says, maybe you're not feeding the cows properly... that's a bitter pill to swallow. Whereas somebody could say, hey, you got stray voltage... it's somebody else's problem.”
— Nigel Cook ([35:35])
- “Somebody comes and says, maybe you're not feeding the cows properly... that's a bitter pill to swallow. Whereas somebody could say, hey, you got stray voltage... it's somebody else's problem.”
-
On the future of the problem:
- “If I was a betting man, I'd wager we're only going to see more cases of stray voltage in the years to come.”
— Matt Kilty ([51:33])
- “If I was a betting man, I'd wager we're only going to see more cases of stray voltage in the years to come.”
Important Timestamps
- Opening & Mystique Introduced: 01:30 – 04:30
- Urine Drinking Behavior: 04:50 – 06:07
- Folk Explanation (Gitte Gyde): 07:05 – 08:52
- Expansion to U.S. Farmers: 09:44 – 10:51
- Stray Voltage Evidence and Farmer Testimony: 11:26 – 12:58
- Electrification Historical Review: 16:42 – 23:38
- Scientific Study—How Much Volts Does it Take?: 27:15 – 29:48
- Animal Health Alternatives (Mineral Deficiency): 31:01 – 32:18
- Social Effects of Modern Barns: 34:01 – 36:32
- Physics 101—Understanding Resistance: 39:38 – 44:25
- Resistance Debate—500 vs. 200 Ohms: 46:48 – 48:59
- Epilogue: What Happened to the Farmers: 49:57 – 51:11
- Looking Forward—Societal Implications: 51:42 – 52:18
Conclusion
- Despite decades of research and regulation, the mystery persists. The debate over stray voltage and its impact on cows straddles folk wisdom, structural changes in farming, and scientific uncertainty about “the resistance of a cow.”
- The podcast leaves listeners with unresolved questions—about science, responsibility, and the pressures facing modern farmers—while chronicling both heartbreak and hope amidst rural electrification’s unintended consequences.
For full details, expert opinions, and the emotional journeys of the farmers, tune in to the complete episode.