A record-breaking bull with a penchant for Mozart lay behind a rush for shares in specialist breeder Genus yesterday.

Semen produced by Picston Shottle, a five-year-old pure-bred Holstein, has sold out until April following unprecedented demand from farmers around the world.

Attempts at boosting his production of semen using biotechnology have failed to keep pace with demand, Genus revealed.

The normal output for a bull is 120,000 doses of semen a year, but Shottle is on target to produce 200,000 at his deluxe stud in Ruthin, North Wales.

Issuing results yesterday that showed a 35 per cent rise in half-year profits to £4.4m, Genus said order levels for semen produced by its 350 bulls were buoyant ahead of the key selling season. Shares rose three per cent following the update.

Mark Smith, global production and product development manager at Genus, said: "We have never had a bull where sales have rocketed as they have done with Shottle. He is the best bull in the world."

Genus provides Shottle with a deep bed of shavings and heat lamps. Because of his size and status, he is kept away from other bulls, so music including classics by Mozart is piped into the shed to ensure he does not feel lonely.

His working week is only three days and staff regularly give Shottle sugar beet to top up his energy levels.

Shottle's semen sells for £35 a sample, which adds up to £7m if he hits the target of 200,000 doses in a year.

Dairy farmers believe cows sired using Shottle's semen will produce milk of better quality, while breeders believe it will improve their pedigree herds.