Hirst hopes to turn a £20,000 doodle into £2m

New works by Damien Hirst, including a sheep with a golden horn and a zebra in formaldehyde, are expected to fetch £65m when they go under the hammer at Sotheby's in September.

The collection, Beautiful Inside My Head Forever, is the first by a major living artist to go straight to sale on the open market rather than via a dealer or gallery.

The 223-lot collection unveiled yesterday contains The Golden Calf, Hirst's largest ever formaldehyde creation, which is expected to fetch £12m. Another, The Black Sheep with the Golden Horn, should sell for more than £2m. Among the cheapest lots are sketches by the artist, which are likely to cost £20,000. "When it comes to the drawing and the inspiration, it is all Damien's," said a spokesman for the auction house. "But when it comes to the construction, he employs people in his workshops to do that."

Sending work straight to auction allows artists to retain greater control over their work and widen the net of buyers. Hirst said it felt "like a natural evolution for contemporary art" but also said he would not stop selling his work through galleries.