Rocky Mountain oysters

Rocky Mountain oysters, or mountain oysters,[1] or meat balls, also known as prairie oysters in Canada (French: animelles), is a dish made of bull testicles. The organs are often deep-fried after being skinned, coated in flour, pepper and salt, and sometimes pounded flat. This delicacy is most often served as an appetizer.[2]

Rocky Mountain oysters

Rocky Mountain oysters, served with lemon and cocktail sauce.
Alternative names	Meat balls, prairie oysters, calf fries, cowboy oysters
Course	Hors d'oeuvre
Region or state	North America West and South Americans
Serving temperature	Hot
Main ingredients	Testicles (bull calf), flour, pepper and, salt
Food energy (per serving)	1 cup = 182 Calories kcal
Cookbook: Rocky Mountain oysters

Raw bovine testicles in an Italian market

The dish is served in parts of Canada, where cattle ranching is prevalent and castration of young male animals is common. "Prairie oysters" is the preferred name in Canada where they are served in a demi-glace.[3] In Oklahoma and the Texas Panhandle, they are often called calf fries. In Spain, Argentina and many parts of Mexico they are referred to as "criadillas", and they are colloquially referred to as huevos de toro (literally, "bull’s eggs"; besides its literal meaning, huevos is a Spanish slang term for testicles) in Central and South America.[4] Rocky Mountain oysters are sometimes confused with cattle fries or animelles (cattle testicles), which are served in a similar manner. A few other terms, such as "cowboy caviar", "Montana tendergroins", "dusted nuts", "swinging beef", or simply “mountain oysters” may be used.[5]

The dish, purportedly cowboy fare,[6] is most commonly found served at festivals, amongst ranching families, or at certain specialty eating establishments and bars.[5] They are, however, also readily available at some public venues (e.g., at Coors Field during Colorado Rockies baseball games). Eagle, Idaho, claims to have the "World's Largest Rocky Mountain Oyster Feed" during its Eagle Fun Days (now held the second weekend in July).[7] Clinton, Montana, Deerfield, Michigan, Huntley, Illinois, Olean, Missouri, Severance, Colorado, and Tiro, Ohio also hold testicle festivals.[8] Rocky Mountain oysters are sometimes served as a prank to those unaware of the origin of these "oysters". They are also considered to be an aphrodisiac by many people.[8]

The primary goal of testicle removal is not culinary. Castration in veterinary practice and animal husbandry is common and serves a variety of purposes, including the control of breeding, the growth of skeletal muscle suitable for beef, and temperament alteration.[9]