'Grandma' produces her 20th offspring

File photo / NZ Herald

A 22-year-old dairy cow has produced 10 times the average number of calves despite being "retired twice".

Bulls couldn't keep away from the Te Awamutu super-mum, a predominantly holstein-friesian cow, born in 1988, and named Grandma.

She has given birth to 20 calves, which is 15 more than the average New Zealand cow produces - cows are often culled from milking herds after five or six years.

Dairy farmer Gordan Kirkham said he retired Grandma twice but just couldn't keep the bulls away, so she ended up romancing with a much younger hereford bull and quietly gave birth to her 19th calf in February.

The average New Zealand cow has around five or six lactations (calvings) in her lifetime and Grandma was definitely the oldest cow he had ever milked, Mr Kirkham said.

According to American researchers at the University of Alabama, one year of bovine chronological age is the equivalent to four human years, making Grandma, the cow equivalent of an 88 year-old human.

The daughter of an artificial insemination bull, Maniapoto AB Mustang, she had always been a reliable, good natured, fertile cow, maintaining a high "production worth" even as she got older, Mr Kirkham said.

Grandma will be left in a paddock close to the farm dairy to mother her white-faced bull calf until weaning - then she'll be retired, again.

"She will remain here on the farm and out to pasture until the end of her days - she deserves that", said Mr Kirkham, who milks 850 cows on his 220ha dairy farm.

- NZPA