15-20 years is the natural life span of cattle. Google it if you like.

In my country, all the wolves got wiped out and cattle are too big for foxes to take on.

Cattle get fewer diseases if they’re not kept inside in cramped conditions eating unnatural bulking food like corn. and are instead allowed to graze grassland freely. Not all of them would live to 20 by a long shot, but a big proportion would make it past 15.

Cows don’t naturally eat corn. It gives them really bad digestion problems, but makes them put on so much fat that it gets stored in little pockets in muscle tissue. The result is meat which has what’s called “marbling” and is seen as a sign of quality and tastiness in the USA. This unnatural feed has health issues for the cattle and it’s common in the USA to give low dosage antibiotics so that fewer animals get sick and have to be put down.

(This is the perfect bedding ground for antibiotic resistant bacteria, and more and more bacteria are evolving antibiotic resistance which means when humans get an infection, they usually die rather than usually live, risking bacterial infection survival rates going back to nearer 19th century levels, when a random cut might just lead to your death. We’re working hard on new antibiotics, but they’re far more expensive than penecillin, and at the moment drug resistance is growing faster than me antibiotics are.)

In my country, only about 5% of cattle are kept inside all year, and they’re almost all grass fed and meat is much leaner, and lean meat like (lean) fillet steak is seen as the highest quality.