Poultry production: broilers and layers
How broilers and layers are raised: strains, housing, brooding, lighting, feeding and FCR, biosecurity, egg production and efficiency sums.
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Chicken is now the most produced meat in the world, and eggs one of the cheapest sources of high-quality protein. Poultry convert feed to food more efficiently than other land livestock, reproduce quickly, need little land, and can be kept at every scale, from a few hens scratching around a village home to houses holding tens of thousands of broilers. These advantages, together with intensive genetic selection, have driven decades of rapid growth in poultry production in every region.
Poultry production systems, management and performance measures are standard topics in animal science and veterinary exams.
Broilers and layers
Modern commercial chickens come from two specialised lines, each produced by a handful of international breeding companies:
- Broilers: meat chickens selected for very fast growth and breast meat; they reach about 2 to 3 kg live weight in five to six weeks under good conditions.
- Layers: egg-laying hens selected for high egg numbers, often over 300 eggs a year, with small bodies and low feed use. White-egg layers derive mainly from the White Leghorn; brown-egg layers from breeds such as the Rhode Island Red.
Dual-purpose and indigenous chickens grow and lay more slowly but are hardier and suited to scavenging and backyard systems, which still supply a large share of eggs and meat in rural Africa and Asia.
Production systems
- Intensive houses with controlled ventilation, lighting, feeding and watering.
- Broilers on deep litter (wood shavings, rice husk).
- Layers in cages, enriched (furnished) colony cages, barns or aviaries. The European Union banned conventional battery cages from 2012, and many retailers and countries are moving toward cage-free eggs.
- Free-range and organic systems with outdoor access.
- Backyard and semi-scavenging systems with low inputs.
Broiler management
- Brooding: chicks need warmth, about 32 to 34 °C at the start, reduced by about 2 to 3 °C each week, plus clean water and feed within hours of placement.
- Space and ventilation: stocking density is often limited by weight per square metre; ventilation removes heat, moisture and ammonia.
- Lighting: programmes with some darkness each day improve health and welfare.
- Feeding: starter, grower and finisher diets based on maize or other grains and soybean meal, with balanced amino acids (lysine, methionine), minerals and vitamins.
- Litter management: dry litter prevents footpad lesions and disease.
- All-in, all-out: one age group per house, followed by cleaning, disinfection and a rest period.
Layer management
- Rearing pullets to the right body weight and uniformity by about 16 to 18 weeks.
- Lighting: increasing day length brings hens into lay; a steady 14 to 16 hours of light maintains production.
- Feeding: diets rich in calcium (about 3.5 to 4.5 per cent) for strong eggshells, provided partly as coarse limestone or shell grit.
- Peak production above 90 to 95 per cent hen-day in good flocks around 25 to 30 weeks of age, then a slow decline; flocks are often kept to 72 to 90 weeks or longer.
- Egg quality: shell strength, cleanliness, and prompt collection and cooling.
Health and biosecurity
Diseases such as Newcastle disease, avian influenza, infectious bronchitis, Gumboro disease (infectious bursal disease), Marek's disease and coccidiosis can devastate flocks. Prevention relies on vaccination, including in ovo and day-old vaccination in hatcheries, and on biosecurity: fences, footbaths and dedicated clothing, controlling visitors, vehicles, wild birds and rodents, and safe disposal of dead birds and litter.
Measuring performance
- Feed conversion ratio (FCR) = feed eaten ÷ live weight gained (broilers) or feed ÷ egg mass (layers).
- Liveability = percentage of birds surviving.
- European Production Efficiency Factor (EPEF) for broilers combines growth, survival and FCR.
- Hen-day egg production = eggs laid ÷ hens present that day × 100; hen-housed production divides by the number of hens originally housed, so it reflects both laying rate and mortality.
Broiler and layer performance
Broiler flock. 20,000 chicks placed; 19,200 sold (liveability 96 per cent) at 40 days averaging 2.8 kg, eating 86,000 kg of feed.
- Total live weight = 19,200 × 2.8 = 53,760 kg.
- FCR = 86,000 ÷ 53,760 ≈ 1.60.
- EPEF = (liveability × weight in kg) ÷ (age in days × FCR) × 100 = (96 × 2.8) ÷ (40 × 1.60) × 100 = 268.8 ÷ 64 × 100 ≈ 420.
Values above about 400 indicate very good performance.
Layer flock. A hen eats 110 g of feed a day and lays at 90 per cent hen-day production.
- Feed per egg = 110 ÷ 0.90 ≈ 122 g.
- Feed per dozen eggs ≈ 122 × 12 ≈ 1.47 kg.
- With eggs averaging 62 g, FCR = 110 ÷ (0.90 × 62) ≈ 1.97 kg feed per kg of egg.
Challenges
- Welfare of fast-growing broilers (leg problems, heart conditions) and of caged hens, driving interest in slower-growing breeds and cage-free systems.
- Antimicrobial use, now reduced in many countries through better biosecurity, vaccination and bans on growth promoters.
- Feed costs and supply, especially maize and soybean.
- Environmental issues: manure, ammonia, and the land used to grow feed.
- Avian influenza outbreaks and trade restrictions.
Key points
- Broilers are selected for rapid growth; layers for high egg numbers; indigenous chickens for hardiness.
- Systems range from intensive housing to free-range and backyard flocks; conventional battery cages are banned in the EU.
- Brooding warmth, ventilation, lighting, balanced feeding, litter management and all-in, all-out are key to broiler performance.
- Layers need correct pullet rearing, lighting of about 14–16 hours, and calcium-rich diets.
- FCR = feed ÷ gain; EPEF = (liveability × weight) ÷ (age × FCR) × 100; hen-day versus hen-housed production.
- Vaccination and biosecurity protect flocks from major diseases.
What the exams ask
- School-leaving and entrance papers: types of poultry, housing systems and basic management.
- Degree and research-fellowship entrances: broiler and layer management, nutrition, lighting programmes, performance indices and disease prevention.
- Veterinary and professional examinations: flock health programmes, biosecurity planning, economics of poultry units and welfare standards.
Described in general terms: the kind of examination, not a past paper. Laisha never reproduces exam questions.
Questions people ask
Are broilers given hormones to grow fast?
No. Hormones are not used in poultry; their growth comes from genetic selection, balanced feed and management. Antibiotic growth promoters have also been banned in many countries.
Why do layers need extra calcium?
Each eggshell contains about 2 grams of calcium. Hens draw on feed calcium and on special bone stores, and without enough dietary calcium, shells become thin and hens' bones weaken.
Can backyard chickens be profitable?
Yes, at small scale, with low input costs, local markets that value indigenous eggs and meat, vaccination against Newcastle disease, and protection from predators.
Sources
- FAO. Gateway to Poultry Production and Products. FAO, online.
- Leeson, S. and Summers, J. D. Commercial Poultry Nutrition, 3rd edition. Nottingham University Press, 2005.
- Mack, S., Hoffmann, D. and Otte, J. "The contribution of poultry to rural development." World's Poultry Science Journal 61, 7–14 (2005).
- Zuidhof, M. J. et al. "Growth, efficiency, and yield of commercial broilers from 1957, 1978, and 2005." Poultry Science 93, 2970–2982 (2014).
- Council Directive 1999/74/EC laying down minimum standards for the protection of laying hens. European Union, 1999.
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