Agricultural economists say there should be little change in poultry prices after a weak strain of avian flu was found in chickens at a pair of Delaware farms. But that could change if the virus spreads widely or other countries continue to ban all U-S poultry products. Annual poultry exports total more than one-point-seven billion dollars a year. H-L Goodwin, a poultry economist at the University of Arkansas, says many countries that have banned all U-S poultry are likely to take another look at the situation and ban only birds from the affected region. Tyson Foods of Springdale, the nation`s largest poultry producer, has said in a statement that it expects countries to relax nationwide bans to state-specific bans after more information is known.