Several factors affect the size of a chicken's egg. The breed of a chicken is the primary determinant in the size of an egg that that chicken will lay. And it ought be expected that larger chickens will lay large eggs, while smaller chickens will lay average or smaller sized eggs. Beyond these factors, however, there lies the element of nutrition. When hens have the best feed and nutrients available to them, they will produce the optimum-sized egg for their breed.
Choose the right breed. If you want large eggs, choose the right breed for the job. Breeds that lay large eggs include Andalusian, Delaware, Jaerhon, LaFleche, Leghorn, Minorca, Plymouth Rock, Spanish, Welsumer and Wyandotte.
Feed your flock the best feed available, right from the start, to maximise their chances of laying large, quality eggs. Chicks should be fed "chick starter" that features 20 per cent protein. Follow this stage with a phase of "chick grower" or "developer," which characteristically has 14 to 16 per cent protein. Once the chickens have matured and begun laying eggs, feed them "layer" feed, which should have less than 20 per cent protein in the mix.
Give your flock enough calcium. If your chickens are laying thin-shelled eggs or soft-shelled eggs, they aren't getting enough calcium in their diet. To remedy this, place some crushed oyster shells in their feeder, give them cut greens or allow them to forage in a pasture.
Provide necessary nutrients. These nutrients include salt and vitamins A, K, E and D. Check your supply of commercially available chicken feed to see if these nutrients are included before adding additional nutrients.
Keep pens clean. Healthy hens will lay larger eggs, and lay them more consistently, than will unhealthy hens. If you can smell ammonia in your chicken coop, then it is time to clean it out. Keeping pens clean will help eliminate fleas, mites and parasites.
Provide enough light. To ensure consistent laying, provide 12-16 hours of light each day. Chickens who aren't exposed to enough light may produce smaller eggs or may cease laying eggs altogether.
Chickens will lay smaller eggs when they first begin laying. These eggs will gradually increase in size to the breed standard within the first year.
Do not give your hens additional calcium unless the eggs are thin or soft-shelled. Too much calcium in their diet can cause kidney failure. Most commercial feed mixes provide the right amount of calcium needed for your flock.