The Sazerac Co's Buffalo Trace Distillery has asked US retailers not to increase prices on this year's Van Winkle Bourbon releases after yields were down by as much as half.

The distillery said more liquid than usual had been lost to the “angel's share”, the amount of alcohol that evaporates from the casks during maturation. It has meant less 15 year-old Pappy Van Winkle, and about half as much 20-year-old and 23-year-old as last year.

However, the company urged whiskey stores to keep prices level.

“Although a lot of retailers charge more than our suggested pricing, we are not asking them to do so,” said Julian Van Winkle, the president of Old Rip Van Winkle Distillery. “We have not raised prices and do not intend to do so drastically in the future.”

Buffalo Trace Distillery produces the Van Winkle Bourbon range in partnership with Old Rip Van Winkle Distillery. The brands are re-released every year and include the US$49.99 Old Rip Van Winkle Handmade Bourbon 10 Year Old and the $249.99 Pappy Van Winkle’s Family Reserve Bourbon 23 Year Old.