some clarification on other salmonella vaccines... besides Merck, there is also Lohmann which produces the water fed vaccines that warmachine was referring to... http://www.lahinternational.com/index.php?src=directory&view=products_catalog&srctype=salmonella_lister it appears the difference is that inactive vaccines are administered via injection and the live vaccines are added to water. as far as cost effectiveness, one needs to provide facts and links that support any statement on cost effectiveness of these various vaccines.