, Traditionally, a flock of broilers consist of about 20,000 birds in a growout house that measures 400/500 feet long and 40/50 feet wide, thus providing about eight-tenths of a square foot per bird. Environmental concerns surrounding each of these methods deal with nutrient pollution into the surrounding soil and groundwater – because of these concerns, in many countries and US states the practice of burial in pits is heavily regulated or disallowed. The birds are released daily from hutches or coops. The floor of the house is covered with bedding material consisting of wood chips, rice hulls, or peanut shells. Chickens: Layer Housing, Michael C. Appleby, Encyclopedia of Animal Science. The breeds used are slower growing, more traditional breeds and typically reach slaughter weight at around 12 weeks of age. Water is usually provided by overhead nipple systems, and food in a trough along the front of the cage replenished at regular intervals by a mechanical system.  Diseases can be common and the animals are vulnerable to predators. Many animal rights advocates object to killing chickens for food, the "factory farm conditions" under which they are raised, methods of transport, and slaughter. Some commercial breeds of hen can produce over 300 eggs a year.. , Because broilers are relatively young and have not reached sexual maturity, they exhibit very little aggressive conduct. , Oxfam America reports that huge industrialized poultry operations are under such pressure to maximize profits that workers are denied access to restrooms. The European Union regulates marketing standards for egg farming which specifies a minimum condition for free-range eggs that "hens have continuous daytime access to open air runs, except in the case of temporary restrictions imposed by veterinary authorities". Some houses are equipped with curtain walls, which can be rolled up in good weather to admit natural light and fresh air. Because dry bedding helps maintain flock health, most growout houses have enclosed watering systems (“nipple drinkers”) which reduce spillage. In the UK, organic laying hens are not routinely beak-trimmed. If bacterial levels in the poultry drinking water reach high levels, it can result in bacterial diarrhoea which can lead to blood poisoning should the bacteria spread from the damaged intestines. Wet management is particularly used in battery egg laying operations, where the waste is sluiced out with constantly or occasionally flowing water. The added weight and overcrowding also puts a strain on their hearts and lungs and Ascites can develop. The next step to becoming a successful poultry farmer is to scout for a suitable area to farm. Foer, Jonathan Safran (2009). There are a variety of methods of disposal, the most common being burial, composting, incineration, and rendering.  In 2009 the annual number of chicken raised was estimated at 50 billion, with 6 billion raised in the European Union, over 9 billion raised in the United States and more than 7 billion in China. Cutaneous nociceptors in the chicken beak. Unlike in the United States, this definition also applies to free-range egg-laying hens. Most growout houses built in recent years feature “tunnel ventilation,” in which a bank of fans draws fresh air through the house. In this case, a farmer must run more fans to bring in more clean fresh air. Although the enriched housing system has its advantages such as reduced aggression towards one another and cleaner eggs, modern egg laying breeds often suffer from osteoporosis which results in the chicken's skeletal system being weakened. Department for Environment, Food and Rural Affairs, European Union Council Directive 1999/74/EC, "Global Animal Slaughter Statistics And Charts", "Humans just 0.01% of all life but have destroyed 83% of wild mammals – study", "Food-Animal Production Practices and Drug Use", "Compassion in World Farming – Egg laying hens", "How to Select the Perfect Breed of Best Egg Laying Chickens", "European Union Regulation for marketing standards for eggs – page 25", "Genotype-by-environment interaction with broiler genotypes differing in growth rate.