According to www.halalfoodauthority.co.uk /main_zibah.htm
Zibah is the way Muslims must slaughter an animal or a bird if the meat or by-products are to be consumed by Muslims. If the slaughterer does not say "shahada or tasmiya, Bismillah Allahu Akbar" as the animal is killed, Muslims cannot use it because it is deemed "not hallel" (unclean).
A slaughterhouse producing hallel food must employ enough Muslim men to say shahada over and over as the animals are machine-slaughtered. One man may be expected to perform zibah for 1500 chickens per hour. Slang use: I'm going to zibah that chicken one day.