Poultry farming is the form of animal husbandry which raises domesticated birds such as chickens, ducks, turkeys and geese to produce meat or eggs for food. Chickens raised for eggs are known as layers, whilst chickens raised for meat are called broilers. According to the World Watch Institute, 74 percent of the world’s poultry meat and 68 percent of eggs are produced intensively.
Environmental conditions are often controlled in egg-laying systems. For example, the duration of the light phase is initially increased to prompt the beginning of egg-laying at 16-20 weeks of age and then mimics summer day length which stimulates the hens to continue laying eggs all year round. Normally, egg production occurs only in the warmer months, however, some commercial breeds of hen have been bred to produce an unnatural number, over 300 eggs a year. Broiler chickens are bred to reach their slaughter weight in less than 6 weeks. They have a high rate of leg deformities because the large breast muscles cause distortions of the developing legs and pelvis, and the birds cannot support their increased body weight. The added weight and overcrowding also puts a strain on their hearts and lungs and Ascites can develop. In the UK, up to 19 million broilers die in their sheds from heart failure each year.
Free-range farming
One alternative to intensive poultry farming is free-range farming using lower stocking densities. Free-range poultry farming allows chickens to roam freely for a period of the day, although they are usually confined in sheds at night to protect them from predators or kept indoors if the weather is particularly bad. In the UK, the Department for Environment, Food and Rural Affairs (Defra) states that a free-range chicken must have day-time access to open-air runs during at least half of its life.
“Free-range” chickens aren’t kept in cages, but they can still be crammed by the thousands into dark, filthy sheds. Access to the outside world may be severely limited, and many of these intelligent, inquisitive birds may never see the light of day. Pop-holes are the exits provided in barns to allow free-range hens to get outside. Many barns don’t have enough, and the exits are often blocked by dominant hens asserting the pecking order. On average, less than 10 percent of free-range chickens will be outside at any given time. What’s more, some never go outside at all.
Animal Welfare
Whether a ‘free-range’ hen or a caged bird, the slaughter process is the same for all the animals. In the UK, chickens are either gassed to death or they are hung upside down by their legs while conscious, dragged through a water bath that is intended to stun them, and their throats are cut. Male chicks, who are of no use to the egg industry, are typically killed just hours after hatching. They are gassed to death or thrown into a high-speed grinder while still alive. Females are allowed to live as long as their egg production remains high, but once their bodies start to give out they are sent to the abattoir. Here, they’re shackled upside down and their throats are slit so they can be processed into “low-grade” meat. Many don’t even make it this far, as they simply drop dead on the shed floor, where their bodies are left to rot.
In the UK alone, we now eat more than a staggering 900 million chickens each year. Even more shockingly, less than 10 percent of chickens are produced in what are considered to be 'higher welfare' conditions.
Both intensive and free-range farming have animal welfare concerns. Cannibalism, feather pecking and vent pecking can be common, prompting some farmers to use beak trimming as a preventative measure, although reducing stocking rates would eliminate these problems. Diseases can be common and the animals are vulnerable to predators. Barn systems have been found to have the worst bird welfare. In South-East Asia, a lack of disease control in free range farming has been associated with outbreaks of Avian influenza.
Avian influenza
Avian influenza, known informally as avian flu or bird flu, is a variety of influenza caused by viruses adapted to birds. Bird flu is similar to swine flu, dog flu, horse flu and human flu as an illness caused by strains of influenza viruses that have adapted to a specific host. Out of the three types of influenza viruses (A, B, and C), influenza A virus is a zoonotic infection with a natural reservoir almost entirely in birds. Avian influenza, for most purposes, refers to the influenza A virus. Influenza A was first isolated from a goose in China in 1996 and human infections were first reported in 1997 in Hong Kong.
Though influenza A is adapted to birds, it can also stably adapt and sustain person-to-person transmission. Recent influenza research into the genes of the Spanish flu virus shows it to have genes adapted from both human and avian strains. Pigs can also be infected with human, avian, and swine influenza viruses, allowing for mixtures of genes to create a new virus, which can cause an antigenic shift to a new influenza A virus subtype which most people have little to no immune protection against.
There is also a risk that crowded conditions in chicken farms will allow avian influenza to spread quickly. A United Nations press release states: ‘Governments, local authorities and international agencies need to take a greatly increased role in combating the role of factory-farming, commerce in live poultry, and wildlife markets which provide ideal conditions for the virus to spread and mutate into a more dangerous form.’
In the 1990s, the world's poultry population grew 76% in developing countries and 23% in developed countries, contributing to the increased prevalence of avian influenza. Before the 1990s, it caused high mortality in poultry, but infections were sporadic and contained. Outbreaks have become more common due to the high density and frequent movement of flocks from intensive poultry production.
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