The Doc Martin star, who flew to Mongolia as well as Nevada, California and Europe to film the ITV1 programme, was introduced to the unappetising drink when he lived with a family in Mongolia.

"We stayed with a nomadic Kazakh family who live their lives the way they have for thousands and thousands of years, centred around the horse - they drink fermented mare's milk; I tried it and it's not going to catch on," he revealed.

There were more memorable experiences for the actor - including carving a sheep's head - while making the documentary, in which he travels around the world to explore man's partnership with horses.

Martin said of his hosts: "They're fantastically kind people, very generous-spirited and uncluttered. Boy, can they ride! They hunt with golden eagles on horseback and have competitions. I rode with an eagle on my arm on these stocky horses that they have, they're as tough as anything."

The star also had an unforgettable trip to Abu Dhabi.

He said: "I rode an Arabian horse through the sand dunes of Abu Dhabi in the desert so that was amazing. That was my favourite ride".

He added: "I'd love to have gone to the Spanish riding school in Vienna to see the Lipizzan (horse breed) but it's phenomenally expensive."

:: Horsepower will be shown on ITV1. The fourth series of Doc Martin is available now on DVD.