Pubs closed on March 20 and will not reopen until July 4 at the earliest, according to the government's recently published road map.
That time period will mean that much of the beer left in storage in pubs will be spoiled by the time they reopen, said the British Beer & Pub Association.
The trade body said it was heart-breaking to see so much British beer poured away.
Some unsaleable beer has been used as feed for anaerobic digesters to create organic fertiliser for farming, as well as reused as animal feed.
Emma McClarkin, chief executive of the British Beer & Pub Association, said: "It's a great shame that so much great British beer that should have been enjoyed in community pubs up and down the country has gone to waste.
"People won't have a chance to drink it as it will go off before pubs can reopen.
"Whilst it is good news that some of the beer can be re-used to help out other sectors affected by COVID-19, such as farming, it is still sad that people are unable to enjoy this beer.
"The need to destroy so much beer really shows how much our brewing and pub sectors have been affected by this crisis.
"We believe that pubs should only open when safe to do so, but without additional support now - particularly for those who won't be able to reopen sooner - many more of our nation's pubs and the brewers that supply them with beer will struggle to survive closure and beyond. The government needs to give our sector much more support."