Before the twentieth century, poultry were mostly kept on general farms, and foraged for much of their feed, eating insects, grain spilled by cattle and horses, and plants around the farm. This was often supplemented by grain, household scraps, calcium supplements such as oyster shell, and garden waste.
As farming became more specialized, many farms kept flocks too large to be fed in this way, and nutritionally complete poultry feed was developed. Modern feeds for poultry consists largely of grain, protein supplements such as soybean oil meal, mineral supplements, and vitamin supplements. The quantity of feed, and the nutritional requirements of the feed, depend on the weight and age of the poultry, their rate of growth, their rate of egg production, the weather (cold or wet weather causes higher energy expenditure), and the amount of nutrition the poultry obtain from foraging. This results in a wide variety of feed formulations. The substitution of less expensive local ingredients introduces additional variations.
A broiler is any chicken (Gallus gallus domesticus) that is bred and raised specifically for meat production. Most commercial broilers reach slaughter weight between four and seven weeks of age, although slower-growing breeds reach slaughter weight at approximately 14 weeks of age. Typical broilers have white feathers and yellowish skin. Broiler or sometimes broiler-fryer is also used sometimes to refer specifically to younger chickens under 2.0 kilograms (4+1⁄2 lb), as compared with the larger roasters.
Sonali chicken, the crossbred of Fayoumi female and RIR (Rhode Island Red) male developed in 1986, has been reported to perform better with respect to egg and meat production, rapid growth, and low mortality under scavenging, semi-scavenging, and intensive farming system. It has been taking its place beside the indigenous hens due to its adaptability and acceptability in the climatic conditions of West Bengal. Sonali, with a phenotypic appearance similar to local chicken, has higher market demand than exotic breeds.
Layer chickens are such a special species of hens, which need to be raised from when they are one day old. They start laying eggs commercially from 18-19 weeks of age. They remain to lay eggs continuously till 72-78 weeks of age.