Scandinavia
The sixth day of Christmas (Dec 30) is the day of “Bringing in the Boar.” Two traditions honor the importance of the boar at Solstice tide. In Scandinavia, Frey, the god of sunshine, rode across the sky on his golden-bristled boar. Gulli-burstin, who was seen as a solar image, his spikes representing the rays of the sun.
In the ancient Norse tradition, the intention was to gain favor from Frey in the new year. The boar’s head with an apple in his mouth was carried into the banquet hall on a gold or silver dish to the sounds of trumpets and the songs of minstrels.
In Scandinavia and England Saint Stephen (whose feast day is Dec 26) is shown as tending to horses and bringing a boar’s head to a Yuletide banquet. Christmas ham is an old tradition in Sweden and may have originated as a winter solstice boar sacrifice to Freyr.
Here’s a song from 1607:
The Boar is dead,
Lo, here is his head,
What man could have done more
Than his head off to strike,
Meleager like.
And bring it as I do before.
His living spoiled,
Where good men toiled,
Which makes kind Ceres sorry;
But now, dead and drawn,
he is very good brawn,
And we have brought it for ye.
Then set down the swineherd,
The foe of the vineyard,
Let Baccus crown his fall;
Let this boar’s head and mustard,
Stand for pig,goose and custard,
And so ye are welcome all.
From: The Winter Solstice and other sources.