What marked the end of the cattle kingdom

Corporate structure and frenzied investment/speculation, insufficent grass to support long drives, ranges were shrunk by railroads, severe weather in 1885-1887.
The cattle frontier ended because barbed wire was invented, which replaced the need for cowboys. Weather also influenced the downfall, as blizzards trapped herds and droughts caused fire. These disasters destroyed land, and many animals were lost.

If i remember correctly it was caused by people hurling bodies at a country for some reason and them they all became infected