A herd of goats grazing on a London city farm are getting their teeth into hundreds of unwanted Christmas trees donated by residents in a fundraising drive.

The eight goats can't get enough of the discarded firs, which the Kentish Town City Farm is collecting from outside homes in the area.

Trustee Angela Woods said the project started last year "when one of our staff who's got a real soft spot for the goats saw a video of goats eating Christmas trees and thought, 'Ooh, I might try that'".

The pine needles aren't just a tasty treat but also a "natural de-wormer", she explained, as the goats, including the herd's four-year-old leader Rockie, nibbled on a festive spruce. 

In a video posted on Twitter, the goats bowl over a staff member carrying a tree and tear at its needles as she lies in the mud.

They eat everything except the trunk, leaving it looking "like it's been in a nuclear blast", Woods said.

After pioneering the project last year, the farm has widened its drive to 650 trees – the juiciest of which go the goats. The remainder will be turned into woodchips for a nearby park. 

The trees are collected by a local van company offering vehicles for free.

Locals have booked collection slots for £10 (12 euros), while for £15 they also receive a "goat note" of thanks. The drive is set to raise at least £8,500.

Volunteers collect used Christmas trees before taking them to Kentish Town City Farm in north London.

Some children attach a note back to the goats on their trees, Woods said.

For city dwellers without gardens or fireplaces, disposing of Christmas trees, which are traditionally taken down on January 6, is a perennial headache.

The project is a "perfect solution and it's great for the goats, great for the farm", Woods said.

The city farm – typically community-run spaces designed to give urban dwellers a taste of the land – is the oldest in the country, turning 50 this year. 

When the farm suffered financial problems two years ago, an anonymous Russian donor stepped in and "gave us £100,000" and it is now "financially stable", Woods said.