Broiler chickens have been selected for fast growth and efficient feed conversion. In 1976 it took 63 days for a broiler to reach a market weight of 2 kilograms. In 2001 it took just 35 days. Improved growth and feed efficiency means:

• Birds make better use of feed materials, thereby reducing waste;
• Poultry meat is more affordable.

Fast growth rates have been blamed for a host of broiler welfare concerns (see chart). The broiler industry has attempted to address these concerns through genetic selection and careful management strategies. Modern broilers require exceptional management to ensure bird health. "Birds are sensitive due to genetic selection for increased yields," says Detlef Onderka, an Alberta poultry pathologist. Dr. Joy Mench, Department of Animal Science, University of California, suggests, "One might want to ask ... is it acceptable to breed (or grow) a bird that has to be so carefully managed to stay healthy."

However, through careful management, plant condemnation rates (an indicator of bird health and well-being) have been reduced over the years, says Don Sungaard, an Alberta chicken producer.

Dr. Frank Robinson poultry researcher at the University of Alberta, says, "Selection for fast growth will run into a ceiling eventually." Dr. Ian Duncan, Department of Animal and Poultry Science, University of Guelph adds, "We are reaching the biological limit of growth and it is a mistake to think we can go on and on selecting for increased growth rate without costs to the bird. It also is a mistake to think that we somehow can find an environmental or nutritional solution to these problems. The long-term solution will be a genetic one." Dr. Hank Classen, poultry researcher at the University of Saskatchewan, questions, "Who will make the decision on the maximum growth rate and on what basis?"

Dr. Robinson plants the responsibility for change in the hands of consumers. "Consumers need to accept that food may cost more with slower growing birds." Dr. Mench agrees, "This is part of the larger market demand for a bird with lots of breast meat that can be produced as cheaply as possible."

For the full story on welfare issues related to fast growth in broiler and broiler breeder chickens see AFAC’s reports. Four poultry researchers, two poultry veterinarians, and four industry representatives were directly consulted for this discussion on the complexities inherent in addressing animal welfare issues.

BROILER WELFARE CONCERNS BELIEVED TO BE RELATED TO FAST GROWTH Leg abnormalities E.g., tibial dyschondroplasia, dyschondroplasia, long bone distortion Ascites Heritable condition Metabolic demand for oxygen not met leading to high blood pressure, over development and swelling of the right ventricle and fluid accumulation in the abdominal cavity Sudden Death Syndrome (SDS) Death caused by cardiomyopathy (enlarged heart) Chronic Hunger in Broiler Breeders Feed restriction required due to selection for unnaturally high appetites