Intensive farming creates ideal conditions for spread of avian flu

Author:
Bruce Passmore
Publication:
Toronto Star
Publication Date:
April 13, 2004

 

Over the past month, the Canadian Food Inspection Agency, along with the media and the public, has been trying to get a grasp on the avian influenza outbreak occurring in British Columbia. The blame for the outbreak has been pinned on migrating wild birds and the transportation of the virus on clothes or vehicles of workers.

But are there other factors affecting the spread of the disease? So far, the virus has hit the big, intensive poultry operations hardest, leaving most backyard flocks and organic operations free of infection. Perhaps it’s time to draw the curtain back and see just how these birds are reared and what impact that may have on their vulnerability to disease.

In the wild, natural selection plays an important role in regulating wildlife populations. A disease, perhaps caused by a virus, enters a population and removes those that are unable to defend themselves from the attack. Diversity is the key to the population’s survival. Animals that survive infection and reproduce will likely pass on their ‘resistant’ or ‘tolerant’ genes to future generations. This does not always mean they are immune, but they may be asymptomatic (carriers of the disease). In the case of avian influenza, wild waterfowl (ducks and geese) have undergone such a process, which takes a long time. They are now carriers, but do not necessarily show signs of the disease. Nature has taken its course.

The conditions in modern intensive poultry farms could not be more different than those found in nature. Almost all the chickens bred for meat in North America are the same breed. They are bred specifically to crave food and to grow at an accelerated rate. They are fed a carefully constructed diet, complete with antibiotics for disease control, and are kept in sheds with near-continuous artificial light. They spend their entire short lives eating, sleeping and defecating in the same, confined space and are sent to slaughter at between 34 and 42 days old.

Research (not to mention common sense) tells us that these conditions are unhealthy and stressful for the birds. Metabolic disorders, lameness and skin diseases are common amongst broiler chickens and stress from their artificial environment can impair their immune systems.

Each of these factors makes the intensively-farmed chicken population a jackpot for a virus. The cramped quarters makes transmission from host to host extremely easy. The diversity that is key to the survival of wild bird populations does not exist and chickens’ immune systems are compromised, rendering them susceptible to infection.

If free-range and organic chicken farms in the BC’s Fraser Valley are less affected by avian flu than intensive operators, it suggests they may be less vulnerable. They are more likely to have contact with wild migratory fowl, yet this greater risk has not translated into a correspondingly higher impact from the virus. The logical difference would be from the overall health of the birds, and there is little doubt that better welfare would have some positive effect on health. Additionally, the constant exposure to a myriad of pathogens, may have enabled them to develop a level of resistance, which would then be passed on to successive generations. One BC organic chicken farmer has said his ‘biohazard’ control is biodiversity. Perhaps these are words of wisdom that the intensive poultry industry should take note of.

Intensive farming systems and disease have been linked in a number of cases. The prevalence of diseases and parasites amongst farmed salmon has been widely reported. Exotic Newcastle Disease, which emerged in Southern California last year, hit intensive farms but not backyard, organic ones. And, let us not forget, BSE is the result of intensive farming practice of feeding cows to cows.

Intensive systems are, of course, driven by one thing: economics. Farmers are under unrelenting pressure to produce cheaper food, resulting in the need to make the most of space and resources. And the animal is always the loser.

The CFIA’s investigation into the cause and spread of avian flu should include the role played by the welfare conditions of the poultry affected, including their health, housing and stock densities. They, and the poultry industry, need to start looking at the big picture – the way chickens are treated and the unwanted consequences that result.

If one of those consequences is a devastating disease, the industry has only itself to blame.

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