The Hereford and Normandy breed cows were discovered by the ranch manager in the field.
A veterinary expert who examined the carcases said they had been killed by lightning hitting the wire fence bordering the field where the animals were stood. The incident occurred in Valdez Chico, near Montevideo, Uruguay.
In September, 53 cattle were killed by lightning in Katosi, Uganda. They had been seeking shelter underneath trees, according to local reports.
Lightning hits the earth an average 100 times per second, or 8.6 million times a day.
Each spark of lightning can reach over five miles in length, soar to temperatures of approximately 50,000 degrees Fahrenheit, and contain 100 million electrical volts.