healthy chooks on the way

Healthy chickens
We take antibiotics to cure certain infections and diseases. The chickens we eat have also been dosed with antibiotics to protect against disease in intensive farming. But Australian scientists have now developed a natural treatment to keep the world's giant poultry industry disease free without chemicals. The solution was in the chicken already.

There are 40 billion chickens grown around the world every year for their meat.
Australia alone produces 400 million chickens for meat production - and that's before you start counting all the chickens farmed to produce eggs.

Such intensive farming is potentially a hotbed of disease.

Molecular virologist, Dr Mike Johnson: "They could outbreak in a shed and you could lose the entire shed. We could have 100 percent mortality in a very short period of time. When you have large sheds of chickens - and we're talking about maybe 20 to 40,000 birds in a shed, you have problems of density and disease outbreaks in those big sheds and quite often the only way to control those diseases and particularly those bacterial diseases is to use antibiotics in the feed."

Antibiotics have been used in chicken feed for 20 to 30 years. But there's a world-wide push to restrict the use of such chemicals in animals produced for human consumption/in animals that are grown for humans to eat.

In 1990, Australia's CSIRO - the Commonwealth Scientific and Industrial Research Organisation - started searching for alternatives to antibiotics in the poultry industry.

It focussed on a biological approach to replace chemicals.

They've now developed an effective way of protecting chickens from disease using proteins called cytokines - in particular, gamma interferon, which the body produces naturally.

Gamma interferons are the messenger molecules of the immune system - identifying the infection that's invaded the body and urgently signalling the body's killer T-cells to fight back.

Dr Mike Johnson: "In general terms what we hope is that it will boost the immune system to fight a whole different range of diseases. Gamma interferon is normally called up as the first line of defence when certain viruses come along, when certain bacteria come along and even when certain parasites come along."

While chickens naturally produce gamma interferon on their own, a chicken's immune system is poorly developed when they're hatched.

Dr Mike Johnson: "What we've done is we've taken gamma interferon and we've given it to the chicken early in its life so we trigger those immune responses early in its life and then give it the protection that it needs.

"What we're doing here is - I like to think of it a bit like a battleship in many respects. The battleship is the immune system as such. If you're going to fight something that's coming over the horizon normally you actually have to see it before you respond to it. The response then is bring the fighter planes up on deck and you fire them off shoot down the enemy at the end of the day. What we're doing is by delivering our gamma interferon early, we're bringing the fighter planes up early so they're actually there ready to launch and some of them are already launched and floating around so they've started to arm other parts of the immune response at the same time.. and that's the way I like to think of it, We've pre-armed the chicken to take on whatever might be floating around in the chicken shed at the time."

They've inserted gamma interferon into a virus to create a vaccine, which can be given to the birds in their water or feed.

Dr Mike Johnson: "If you think about how you're going to actually vaccinate those birds, it becomes a physical impossibility to pick a bird up and inoculate it. You need broad range delivery systems and that's where viruses have actually proven themselves to be very effective this way. Because they are stable and you can engineer them easily and when they actually go into the birds they can be eliminated very quickly and because we can put them in the drinking water at a very early age all the flocks get inoculated all at once."

"The virus itself naturally replicates or multiplies in cells in the gut of the chicken."

Immunologist, Dr Andrew Bean: "The bad bacteria invade the body and the immune system recognises this. We give things like vaccines with cytokines and that helps to enhance the immune response so they can then deal with these bad bacteria."

It's one dose for life.

Dr Mike Johnson: "Whereas a chemical approach may mean that you've got to continually feed the chemical into the animal to keep the disease under control."

The virus used in the vaccine is specific to poultry. It can't be transmitted to other animals, including humans.

Dr Mike Johnson: "By the time we get to the end of the production period there is no virus left in the chicken at all so it's in effect the same as any other normal chicken that's brought up."

In trials at the CSIRO's quarantined animal facilities, researchers noticed a positive side effect of boosting gamma interferon levels in young chicks that would normally still be developing their immune systems.

Dr Mike Johnson: "The end result is those birds end up ten percent heavier at the end of the day and they don't eat more food to do so. So there's a nice balance there between the immune system just knocking down bugs as they come along and the bird not having to spend all its time converting disease it can then convert all the energy that's coming in into muscle mass at the end of the growth period."

Dr Johnson claims wider environmental benefits from using this naturally occurring treatment.

Dr Mike Johnson: "If we can get birds to grow to a certain point in their production cycle and in doing so they use 250 grams less of feed per bird - now if you multiply 250 grams by 40 billion and convert that to tonnes of grain that you don't need any more you can then do another mathematical calculation that converts that to how many hectares of land you don't now have to use to produce that grain. So it becomes an issue of, as the world population increases and pig meat and poultry meat become the preferred meats because they are so efficient in converting grains into muscle mass, you don't have to then go out and destroy more arable land or produce more arable land to produce the grain to feed the animals. It becomes a way of saving environmental impact in the long run as well as reducing the chemical impact that's actually used in the birds itself."

The gamma interferon treatment is now undergoing further trials in Europe and the United States to prove that it is safe for use in chickens. Because of the rigorous testing required to register a product, it will be another three to five years before it's available for commercial use.