Eight billion broiler chickens and 300 million laying hens are in U.S. agribusiness production each year, with hundreds of thousands, even millions, of birds on a single farm. In this gigantic system individual birds have little value: a whole broiler chicken is worth $4 and the yearly output of  eggs per hen amounts to $30. More than 99% of U.S. laying hens are in cages, averaging 8 hens per cage. Hens in cages develop osteoporosis because they get no exercise and because their limited calcium is mobilized for constant eggshell formation instead of for bones.
Welfare Problems of Meat-type Chickens
Ian J.H. Duncan, PhD, Professor of Poultry Ethology, Chair
in Animal Welfare, University of Guelph, Ontario, Canada
These chickens, including both the breeding flocks and the [baby] broiler chickens derived from them, represent welfare problems on a huge scale. By welfare, I mean what animals feel. Strong negative feelingssufferinginclude pain, frustration, and fear. The biggest modern problem with meat-type chickens and turkeys is not infectious disease [which is still rampant] but metabolic.
Heart and Lung Problems: These birds have been genetically selected for fast growing soft muscle tissue. The heart and lungs have a hard time supplying this fast growing soft tissue with oxygenated blood. This can lead to aortic rupture in turkeys, sudden death syndrome (heart attacks) in chickens, and an accumulation of venous blood fluid in the body cavities--ascites syndromeresulting in suffocation. Ascites is responsible for 5 12% mortality in meat-type chickens.
Skeletal Problems: The combination of forced rapid growth and excessive weight causes chronic, painful lameness and abnormal gait in meat-type birds. The birds body grows too fast for the bone plates to accommodate. Consequently the birds develop angular bone deformities, tibiadyschondroplasia, and kinky back, in which vertebrae snap and put pressure on the spinal chord, causing paralysis. In breeder turkeys, cartilage gets eaten away at the hip joint because of the overweight. These are not senile turkeys; they are young turkeys. Studies in which lame chickens and turkeys are given painkillers or a choice between food with painkillers versus food without show that these birds are in pain. They choose the painkilling food, and they become more active. Crippled birds suffer also because they may be starving and thirsty and because they cannot avoid aggressive attacks in the crowded sheds.
Ascites and skeletal problems are increasing in meat-type chickens and turkeys, which isnt surprising. While in the 1950s it took 12 weeks to raise a five pound chicken, the time has been reduced to 6 weeks, at enormous cost to the birds. These birds are all extremely unfit. In treadmill experiments, for example, their core body temperature goes up abnormally high. There is also the interaction between their unfitness and their poor environment. The poultry environment is full of dust and ammonia which get into the birds lungs. Ammonia destroys the cilia that would otherwise prevent harmful bacteria from being inhaled. As a result, the birds develop respiratory infections such as airsacculitis. They are inhaling harmful bacteria constantly.
Elective Surgeries Mutilations: Male breeder chickens are detoed, beak-trimmed and their combs are dubbed (cut off). Turkeys used for breeding are detoed and beak- trimmed, and the male turkeys snoods are cut off (desnooded). All these elective surgeries involve pain, perhaps chronic pain. No anaesthetic is ever given to the birds. These mutilations are crude solutions to problems created by modern methods of raising chickens and turkeys. For example, broiler breeder males have been bred, consciously or unconsciously, for hyperaggressiveness. They injure and cause fear in the hens, who cannot escape from these roosters in the breeder houses. Worse, to keep their weight down, meat-type breeder chickens are given only 40 50% of the amount of food they would normally eat. They are chronically hungry. Their abnormal behavior, such as compulsive pecking, shows they are obviously suffering.
Young birds: A big welfare problem for the chicks and poults (baby turkeys) is that the poultry industry wants meat-type birds to start eating immediately. Lights are kept burning in the sheds and the birds are prodded to eat. Consequently, young chickens and turkeys do not get enough rest. By contrast, in nature, hens brood their young periodically throughout the day and continuously through the night to provide both warmth and rest.
Catching, Transportation, and Slaughter. All of these activities are extremely stressful as currently performed. Automated chicken catching machines (harvesters) are less stressful than manual catching. Inert gas stunning using, say, argon mixed with nitrogen, would be more humane that the current method of electrically immobilizing the [conscious] birds. Preferably, birds should be stunned in the transport crates, prior to shackling. This would eliminate the stress of being grabbed and shackled while fully conscious as is now the case. It would also be better for the shacklers because there would be less noise, less dust, more light, and better ergonomics.
The next issue of PoultryPress will include a synopsis of the talks by Dr. Lesley Rogers and Dr. Gisela Kaplan, who spoke respectively about Changing Our Views About the Domestic Chicken and Emotions and Awareness in Birds.