Any 'warm' Food During Rainy Spells

Hi

The recent long cold weather is causing most of my birds to fluff up.
Any food that could keep them warm, please?

Some years back, I tried adding Baby Cham to water and my singing birds loved it and exploded into full song. A friend swears by it for his canary breeding. In fact, a foreign breeder is nicknamed Ms Gordon Bleu for obvious reason.

I have, however, stop the practice after reading the negative effects of alcohol on birds.

Brgds