Britain has won the right to export pig semen to China in a deal worth £45m a year.

Owen Paterson, the environment secretary, who is accompanying David Cameron on his trip to China, has also embarked on negotiations to export pigs' trotters – a local delicacy – to China.

Under the deal with China, the "porcine semen" can be flown to the country in frozen and fresh form. Pigs will not be flying but their seed will take to the air.

A No 10 spokesperson said: "We're doing all we can to ensure that businesses up and down the country reap the rewards from our relationship with China. And that includes our pig farmers. This new deal to export pig semen will be worth £45m to UK firms and means Britain's best pigs will help sustain the largest pig population in the world.

"And we're not stopping there, we're talking to the Chinese about serving up pigs trotters on Beijing's finest dining tables. That would be a real win-win – a multimillion pound boost for Britain and a gastronomic treat for Chinese diners."

The exports start in the first quarter of next year. Four UK artificial insemination centres, based in England and Northern Ireland, will start making preparations for the exports in the new year.

Half of the world's pigs are in China but the country needs to improve pig genetics. A government source said: "China has an interest to increase the efficiency of their production, while minimising the environmental impact of increased production. The UK industry for pig production can play a large and important role in helping China achieve greater efficiency through the provision of high-quality genetic stock.

"UK porcine semen will be key to help the Chinese improve their pig production and make the industry more productive in the long term. The quantities are not the important factor for this trade; it is the quality that is important."