Second week of January: a queue at the gate, cash only, half a dozen eggs, and the woman at the front of it has kept hens for 30 years. Her feed bill last month ran higher than her heating bill, and every nest box on the place is empty. Nothing is wrong with her birds. A hen reads the length of the day through her eye, and once the daylight falls under 12 hours the hormone chain that ripens yolks goes quiet, so no weight of pellets in the trough answers a message that was never sent. Cold finishes the arithmetic: her body runs at 105 to 107 degrees Fahrenheit, she spends feed on heat instead of on eggs, and she walks out of lay weeks before anyone touches her ration. Up the hill, in a row of old cottages, nobody has bought a sack of feed in living memory and the basket still fills every morning, out of twelve ordinary things that never came in a bag.

The order is where nearly everybody goes wrong, and the old method starts at the coop door with two tins. Grit stays down in the gizzard as a set of little millstones and grinds grain fine enough for the gut to absorb it, while oyster shell dissolves on purpose, because a shell is roughly 95% calcium carbonate and a hen needs about 2 g of calcium per egg, taken from feed or pulled out of her own bones. Muddle the tins and you get chalky, thin or shell-less eggs. Beside them sits the ash tin from a stove that went cold, sieved for nails and clinker, carrying calcium, potassium and phosphorus, with coal ash and anything swept from under painted or treated timber going in the bin where it belongs. Dried seaweed off the shore, crumbled and stirred through the ration, brings iodine and a long tail of trace minerals that thin, sandy inland ground has nothing to pass up the chain. Charcoal in a tin does the work no mineral can, because a hen cannot vomit: mouldy grain and spoiled scraps stay swallowed, and the birds that go for the charcoal are usually the ones already in trouble. Then the scrap pail, which was a genuine ration in the old system and is, in the UK, illegal, banned since the foot-and-mouth outbreak of 2001 for anything that has passed through a kitchen. Three winter dangers sit alongside it: onion and garlic stripping red cells until a comb goes pale and grey, mouldy wheat and maize drifting a flock off its feed until a liver gives out, and raw dried beans, kidney beans worst of all, safe only once they are soaked and boiled.

Soured grain is where the feed bill drops. Grain into a bucket, water an inch over it, a loose lid, and 3 days later it smells like beer and sour bread, that smell being the signal. Phytic acid breaks down in the soak, and a hen that needed 4 oz of dry grain a day holds her lay on closer to 3 oz of the soured stuff, which through a hard January is the difference between buying another bag and not. The yard supplies the rest of the protein: nettles cut young and wilted a day, comfrey at a leaf or two per bird, and the maggot bucket fed fat, white and fresh, never black and reeking. Oat husks and chop give the gizzard a muscle to work against, about a tenth of the ration by volume, and a hen short on roughage says so by pulling feathers around the vent and tail base months before the egg count falls. Water counts as an ingredient, fresh twice a day and brought up to blood warmth, because below 50°F she drinks less, eats less and lays less. Last comes the twelfth thing, two spoonfuls of the sourdough culture kept for bread, stirred through the morning grain until the feeder smells faintly of beer. Assembled in that order it stops being twelve things, and January looks the way it used to: same frost, same short daylight, and a basket full enough to hand half a dozen over the fence without a word.