The layers' ration always comes first

A hen in lay is doing something remarkable. She is producing an egg most days, converting feed into shell, white and yolk with impressive efficiency. A good-quality layers' pellet or mash is formulated to give her everything she needs: around 16 to 17% protein, a careful balance of calcium and phosphorus, plus vitamins and minerals in the right proportions. Everything else you offer sits on top of that foundation. As a rule of thumb, treats and extras should make up no more than about 10% of her daily intake by weight. For a typical hybrid hen eating 120g of pellets a day, that is roughly a small handful of extras, not a bowlful. Get the balance wrong — too much corn, too much bread, too many kitchen scraps — and you will see it in the nest box: thinner shells, fewer eggs, and hens that look well-fed but are quietly short of protein and calcium.

Grit: essential for digestion

Hens do not have teeth. They swallow food whole and grind it in a muscular organ called the gizzard, using small stones they have picked up. In a small garden with paving, decking or neat borders, there may not be enough suitable stone within reach. That is where insoluble grit comes in, often sold as flint grit or poultry grit. Offer it in a small, sturdy pot fixed at hen height and let them help themselves. Birds on a mixed diet of pellets and occasional greens will generally take what they need. It is not the same thing as oyster shell, and you need both. If your hens free-range over rough, stony ground they may find their own, but a pot of grit is cheap insurance and takes up almost no space.

Oyster shell: calcium on demand

Oyster shell is the soluble counterpart to grit. It dissolves in the gut and supplies the calcium a hen needs to build a shell — she requires roughly 4g in her diet for every egg she lays. Layers' pellets contain calcium, but some hens need more, particularly as they come into lay, through the moult, or during hot spells when they eat less overall. The elegant part is that hens can regulate their own intake if you let them. Keep oyster shell in a separate hopper rather than mixing it into the feed, so each bird can take what she needs. Hens often take more in the late afternoon and evening, because shell formation happens overnight. If you are seeing thin, soft or misshapen shells despite a good ration, freely available oyster shell is the first thing to try.

Corn and scratch: a useful winter extra

Mixed corn — wheat, maize and sometimes barley — is a traditional treat, and a pleasant one to scatter. It is high in energy and low in protein and calcium, so it is a supplement, never a substitute. Scatter a small handful per bird in the late afternoon during cold weather; the slow digestion of maize helps keep them warm overnight. In summer, cut it right back. Never put corn down first thing in the morning when hens are hungriest, or they will fill up on it and ignore the pellets that actually keep them laying. A little wheat or a sprinkling of scratch in the run is fine, but keep it within that 10% ceiling.

Safe treats from the kitchen and garden

Plenty of ordinary foods are genuinely useful, and most of them cost nothing.

• Leafy greens: cabbage, kale, chard and cauliflower leaves, hung up so they are not trampled into the mud. Spinach is fine occasionally, but it binds calcium, so do not make it a daily habit.
• Fruit: apple, pear and berry windfalls, chopped small. Avoid citrus in any quantity, as it can upset digestion.
• Vegetables: grated carrot, cooked potato (never green or sprouting), cooked squash, peas and sweetcorn.
• Protein extras: a few mealworms, sunflower seeds or a spoonful of plain porridge oats in cold weather. During the moult, a little extra protein helps new feathers come through.
• Herbs and aromatics: oregano, thyme and a small amount of garlic are popular for general wellbeing. Apple cider vinegar in the drinker at around 10ml per litre is a traditional tonic, though fresh, clean water matters far more.

Introduce anything new in small amounts and watch for changes in droppings or appetite. Hens are individuals, and what suits one flock may not suit another.

What to avoid, and why

Some popular "treats" do more harm than good. Bread, cake, biscuits, chips and other processed human snacks are the main offenders: they fill hens up, dilute the balanced ration, and add salt and fat that poultry cannot handle well. Chocolate and avocado are toxic. Raw potato peelings, onion, rhubarb leaves and anything mouldy should go nowhere near the run. Salty leftovers, caffeine and alcohol are all off the menu. It is also worth resisting the urge to add supplements to the water or feed "just in case". A flock on a good layers' ration, with grit and oyster shell always available, is usually getting everything it needs. Extra vitamins and tonics can unbalance the diet and are rarely the answer. Keep the staples right, use treats sparingly, and your hens will reward you with strong shells and steady laying right through the year.