Broiler chickens

Overcrowded chicken sheds

Each year 48 billion "broiler" chickens are reared for meat worldwide. The vast majority are farmed intensively at high densities (up to 20 birds/m2) in windowless sheds holding up to 50,000 birds. As the chickens grow bigger, crowding becomes a severe problem. They have nowhere to rest except on faeces-laden litter, and often suffer breast blisters, hock burns and other skin problems.

Accelerated growth

Broilers are made to grow at such an accelerated rate - through a combination of genetics, high-protein feed and often growth-promoting chemicals - that their bones cannot keep pace. The skeleton of a 6-week old bird now carries the equivalent weight of a 12-week old bird. As a result, before reaching their slaughter weight at around 42 days (twice as fast as they did 40 years ago - a chicken's natural life span is around 7 years), millions suffer from crippling leg disorders each year. Lameness causes both poor welfare and economic losses. In the worst cases, they can barely walk and can only move by crawling on their shanks. Some, unable to reach the food and water points, die of starvation or thirst. Their hearts and lungs also fail to support their overdeveloped bodies, and each year millions succumb to heart failure. Heart failure due to abnormally fast growth rates is now one of the major causes of carcase condemnation in broilers worldwide.

The health problems of meat chickens caused by rapid growth are so severe that if – instead of being slaughtered at six weeks – they were allowed to live on, many would die before reaching sexual maturity at around 18 weeks. This presents a major problem for the breeding flock. These chickens must not only survive into adulthood, but also remain sufficiently healthy to breed. If the breeders grew as quickly as their offspring, many would die before adulthood and the survivors would have poor fertility. In order to slow down the breeders’ growth rate, the industry feeds them on such severely restricted rations that scientists stress that these chickens are “very hungry”.

Chickens can feel pain. In a classic study, chickens were allowed to choose between their normal feed and feed that contained a pain-killing drug. The lame chickens selected more of the feed containing the pain-killer, whereas the non-lame birds chose the normal feed.

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