Cows can live that long but after production drops (about 4 years) they will be sold off for beef. Not breeding cows would definitely help. https://en.wikipedi

Cows can live that long but after production drops (about 4 years) they will be sold off for beef. Not breeding cows would definitely help. https://en.wikipedia.org/wiki/Dairy_cattle https://en.wikipedia.org/wiki/Dairy_cattle lists a few sources for the 4 years figure.