Black or pink - teats are same

Farming folklore linking the shape and colour of a cow's teats to its vulnerability to mastitis can be consigned to history, according to a new scientific study.

A herd of about 570 predominantly holstein-friesian cattle were used in the Lincoln University project conducted in association with a team from farming consultancy service Dexcel.

No connection was found between the frequency of mastitis infection and the type, shape or pigmentation of a cow's teats.

The cost to the dairy industry of lost production and treatment for cows suffering mastitis is as much as $200 million a year, says Lachlan McKenzie, vice-chairman of Dairy Farmers New Zealand.

Cows infected with mastitis can cost $200 each in treatment and lost production.

McKenzie runs a 1200-head dairy farm in Rotorua and mastitis is his single biggest animal health cost and can lead to the culling of up to 5 per cent of the herd in any one year.

Associating different types of teat with the disease is widespread, he says.

"It's common belief, folklore if you like to call it, that black teats are better than pink teats."

Researchers visually scored cows suffering from mastitis for general teat shape, teat-end shape and pigmentation. Samples of the quarter foremilk were collected for bacteriological analyses and somatic cell count, which is an indicator of teat health, each week for 14 weeks.

In total 439 teats were scored and 5032 milk samples were analysed.

The most common teat shape was cylindrical at 51 per cent, followed by funnel shaped at 32.5 per cent, with the remaining 16.5 per cent consisting of three other shapes.

These results were not considered by researchers to be unusual or show greater propensity of any particular teat type to mastitis.

The study will lay to rest concerns that some cows are more susceptible because of their teat type, says Jon Hickford, project supervisor.

"If you spend too long at a dairy herd looking at the back end of a cow you immediately start speculating about what things predispose some cows to mastitis ... we would hope that this dispels some of the needless speculation that occurs."

However, it is important to note that this study was conducted on one breed and the findings should not be applied automatically to other breeds without further investigation, he adds.

The discovery of a link between the distance of the teat from the ground and the frequency of infection from the external environment was common sense, Hickford says. The dairy industry could also get a boost from being able to make greater use of bulls which have bred cows with previously suspect teat shapes that were otherwise good milk producers.

"You're losing what we call genetic potential," he says. "You're taking out sires that actually may have been quite useful."

The study is part of a wider investigation into the genetic make up of cows suffering mastitis which has been underway for six years.

"Everything in science takes a long time," Hickford says. The research will also help other countries where farming folklore is just as common.

"These simple questions are so often not answered and it's something that has universal appeal."