What animal's meat is traditionally used to make hamburgers?

Cow

https://en.wikipedia.org/wiki/Hamburger

Other (non-english, therefore not cited) articles elaborate more on the fact that traditionally only beef is used.

Bovine. Cows give Milk and Cattle give Meat!

"Beef is the culinary name for meat from bovines, especially domestic cattle."

https://en.wikipedia.org/wiki/Beef

bo·vine – adjective

1. of or pertaining to the subfamily Bovinae, which includes cattle, buffalo, and kudus.

http://dictionary.reference.com/browse/bovine

Most hamburgers are made from BEEF which comes from "cattle" -- Regardless of sex.

Today's beef comes from cows (females that have borne at least one calf), steers (males castrated when very young), heifers (females that have never borne a calf) and bulls under 2 years old. Baby beef is the lean, tender but not too flavorful meat of a 7- to 10-month-old calf.

http://www.foodterms.com/encyclopedia/beef/index.html

I don't know if Cubbo is looking for something more specific than "beef." A factlet surfaced in my brain from an animal husbandry course I took, oh, 35 yrs. ago in which I learned about "bologna bulls." They weren't necessarily made into bologna, but most of their meat was ground since it was so tough. This dictionary says it's turned into "mince" or bologna.
http://medical-dictionary.thefreedictionary.com/bologna+bull
The textbook was "Introductory Animal Husbandry"
by Arthur Laurence Anderson, 1955 edition.
Rule of thumb: the better the beef before grinding, the better after.

"Generally, ground beef is made from the less tender and less popular cuts of beef. Trimmings from more tender cuts may also be used. Grinding tenderizes the meat and the fat reduces its dryness and improves flavor."
https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/meat/ground-beef-and-food-safety

One last word from a genuine cattleman:
"They're a fat cattle market and we're just going to kill the culls -- the hamburger and baloney cows."
http://news.minnesota.publicradio.org/features/2005/06/30_rehab_canadabeef/