Alan Barrett of the University of Texas says travel by carriers of influenza, be they people in aeroplanes or birds on the wing, means regional mutations quickly spread around the world.

All farmed chickens, turkeys, and pigs spend their brief lives in dark and crowded warehouses, many of them so cramped that they can't even turn around or spread a single wing.

So it is very important to study the parameters of the pass and techniques for the spread of the wing plate steel.