The unnatural growth rate of broilers, together with the lack of space to move or exercise, encourages the birds to rest on the litter. As broilers spend their entire lives in direct contact with the bedding their health and welfare are linked to its quality.(5). Conditions such as hock burn, breast blisters, skeletal disorders, lameness and heart-failure are consequences of management-related problems.
Hock burn & breast blisters
When caked litter accumulates the wet droppings on the surface cause inflammation of the skin over the hock, (hocks are the joint in the hind legs). This may lead to ulceration followed by scabs over the ulcers. Hock burn is extremely painful for the bird and can often be seen on chickens sold in supermarkets. Soiled litter can also affect the bird’s breast leading to blisters which if they become infected leads to abscess formation. As these birds spend more of their time sitting on the damp litter this ultimately accelerates the incidence of leg weakness.
Skeletal disorders & lameness
The two main disorders affecting broilers are due to their rapid growth rates. Bone growth disorders affect young birds whilst arthritis is prevalent among broiler breeders. In birds over around 35 days the structure supporting the bird (bones, tendons and ligaments) often cannot keep pace with the growth of muscle and fat(5). A DEFRA-funded study, conducted by a team of independent researchers at Bristol University, showed that almost 30% of broilers had moderate to severe leg disorders that impaired their ability to move. This indicates that over 200 million broilers in the UK suffer from lameness, and scientific research strongly suggests, this is painful for the birds. Some of the chickens have difficulty reaching food/water and in the worst cases they can barely move at all(6).
Fast growing broilers suffer from 2 forms of heart disease, ascites and Sudden Death Syndrome (SDS). These conditions are due likely to the fact that the broilers’ require high oxygen levels to keep up with their metabolism which in turn intensifies the activity of their cardio-pulmonary systems.
Chickens, like humans, are sensitive to ammonia. Prolonged exposure to high levels (50 to 100 parts per million) can result in kerato-conjunctivitis, this is a painful eye condition leading to blindness(7).
The unhealthy, intensive nature of broiler farms means bacteria can spread easily through flocks. Salmonella and Campylobacter are widespread in broiler farms and frequent causes of food poisoning in humans.
Avian influenza is a highly contagious viral disease affecting the respiratory, digestive and/or nervous system of many species of birds. It is caused by a Type A influenza virus, a disease which must be notified to the local State Veterinary Service Divisional Veterinary Manager. There are two types of avian influenza virus, low pathogenic (LPAI) and highly pathogenic (HPAI). Within the LPAI types there is evidence that certain H5 and H7 viruses may mutate and become highly pathogenic. On April 5th 2006 a dead swan which was found in Scotland tested positive for the highly pathogenic virus H5N1. On February 3rd 2007, H5N1 was confirmed on a poultry farm in Holton, Suffolk. A 3 km Protection Zone (PZ) and 10 km Surveillance Zone (SZ) were imposed along with a wider Restricted Zone. On March 12th 2007 the restrictions around the farm in Holton were lifted. Only the movement of meat produced from birds originating within the PZ that were killed prior to the PZ merging with the SZ will need to continue to be licensed and reported. A Food Standards Agency (FSA) investigation has thoroughly examined the possibility that food waste at the Bernard Matthews cutting plant at Holton may have been stored inappropriately. The investigation concluded that there was no evidence of any offences under the Animal By-Products Regulations 2005. All of the evidence collected indicates that the infection has not spread beyond one site. Defra have not yet located the exact source of the infection but the lack of evidence of another outbreak indicates that the risk of spread of infection has now reduced. European Union (EU) trade will recommence from the restriction zones and Defra are working with exporters, British Embassies overseas and non-EU countries’ veterinary authorities to try to keep export markets open and to facilitate exports (1).
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