On one Wisconsin farm, the study shows the number of 3rd harmonics ranged from 14 to 3,451 per day and caused milk production to fall between 17 to 20 percent. Readings from the same farm showed milk production also decreased when there was an increase in electrical events. But since animal health is the tone of the complaints on farms with transient voltages, we are suggesting that detailed studies be done. Milk production on all the farms increases or decreases on the same days in correlation with electrical events, even though some of the farms are more than 10 miles apart. I think we should expect it is having effects on other productive systems of the cow like reproduction, resistance to disease and general animal health.
Utility companies say there is no evidence that the currents harm cows.
There is also disagreement that they are caused by harmonics. Mark Cook, manager of the Wisconsin Public Service Commission Rural Electric Power Services Program, said the levels of voltage that are recognized by the state to cause cows problems are higher than what Stetzer is reading. The study says health and mortality of cows and calves are seriously affected by the electrical readings. The average mortality rate among 946 herds in Michigan was 3.9 percent. He refers to a 1997 EPRI publication about transients.