Big Bertha, Irish cattle and twice Guinness World Record holder (oldest cow, cow with most offspring) (born 1945)

Big Bertha was a cow who held two Guinness World Records: she was the oldest cow recorded, dying just three months short of her 49th birthday, and she also held the record for lifetime breeding, having produced 39 calves. During her lifetime she helped raise $75,000 for cancer research and other charities.

Cattle are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus Bos. Mature female cattle are called cows and mature male cattle are bulls. Young female cattle are called heifers, young male cattle are oxen or bullocks, and castrated male cattle are known as steers.

Guinness World Records, known from its inception in 1955 until 1999 as The Guinness Book of Records and in previous United States editions as The Guinness Book of World Records, is a British reference book published annually, listing world records both of human achievements and the extremes of the natural world. Sir Hugh Beaver created the concept, and twin brothers Norris and Ross McWhirter co-founded the book in London in August 1955.

December 31 is the 365th day of the year in the Gregorian calendar. It is known by a collection of names including: Saint Sylvester's Day, New Year's Eve or Old Year's Day/Night, as the following day is New Year's Day. It is the last day of the year; the following day is January 1, the first day of the following year.