Image caption Children with allergies in Italy have shown they prefer the taste of donkeys' milk to other alternatives

In the hills outside Bologna in northern Italy a slightly peculiar farm has become the centre of a health experiment that harks back to the practices of ancient Greece and Rome.

The farm is home to 700 donkeys and produces donkey milk, a product that is creating a lot of interest among health professionals.

Donkey milk is proving to be a viable alternative for young children and infants in Italy who suffer from allergies to cows' milk.

More than 50% of what the farm produces is sold directly to paediatric units in the region.

Dr Giovanna Monti, a paediatrician at the head of the allergy unit at Turin's St Anna hospital, has been studying the effects of donkey milk on babies and children since 2004.

"We use this milk mostly for children who are allergic to certain proteins in cows' milk," she told the BBC World Service's Health Check programme. "These proteins are often also present in formulated milk too."

This milk is very similar to human milk Dr Giovanni Monti, Paediatrician

Better than soy

"This milk is very similar to human milk" Dr Monti explains, and it has many benefits.

With a low saturated fat content and high levels of omega three and six - the nutrients found in oily fish - it can help lower cholesterol.

It also has high levels of calcium - especially important for young children - and contains the enzyme Lysozeme, which is anti-bacterial and can protect against intestinal infections.

Though it doesn't have enough calories to feed a newborn baby alone, Dr Monti expects it will be easily made into a formula substitute in the near future.

Allergies are currently on the rise in industrialised countries and lactose intolerance is especially high in southern Europe and Italy in particular.

While goat and sheep's milk have been traditional alternatives, they cannot be used in about 90% of cases of cows' milk allergies because the allergens are the same.

Image caption Outside Italy other alternatives to cows milk are still favoured

Soya milk has also been a common alternative but soy allergies are also rising among the children, so Dr Monti and her colleagues have naturally veered towards donkeys.

Ancient alternative

The use of donkey milk is far from a modern fad.

As long ago as 460BC "the father of medicine", Hippocrates, proscribed the nectar of the beast of burden for anything from snake bites to nosebleeds.

Ancient Greeks were said to feed it to their children, while stories from the time of the Romans tell of donkey milk being used as a cosmetic to soften the skin.

Legend has it that Cleopatra also bathed in asses milk to enhance her beauty.

Up until the 19th century in the UK, donkey milk was widely sold as an alternative to breast milk.

However, donkey milk is not that easy to produce, as Davide Borghi, who runs the donkey farm on the hills of Montebaducco, explains.

"Cows have been bred to be milk producing machines" he says, "but donkeys have never been bred that way so it's much more difficult for them to produce lots of milk."

A donkey only has two teats, rather than a cow's four, and milking only produces about a litre a day per animal - a cow can produce more than 10 times that.

What's more, a donkey can only be milked for about six months after producing a foal, and even then only when the foal is close by.

Borghi acknowledges that these limitations mean donkey milk is likely to remain a niche health product.

"We're not trying to substitute cows' milk, it's just an alternative for children who are allergic."