I read a report recently as well which doesn't seem to be getting any mention as an arguement against culling that a bovine liver fluke, common in cattle prevents the TB test from giving correct indication of the presence of TB. Therefore herds infected with TB are not detected....Just found the article..http://www.nature.com/news/bovi
ne-tb-disguised-by-liver-fluke-1.10685...
FULL ARTICLE AT The Observer