Laws pertaining to the Slaughterer

Reciting the Tasmiyyah at the time Slaughter

Q: I am a PhD, Electronics Engineering, student in Torino, Italy. I have a question regarding chicken meat. There is a slaughter house near our city where Arab Muslim use to slaughter chickens. He slaughters the chicken by hand. Usually he has to slaughter approximately 7,500 chickens in 6 hours. He use to say Takbeer randomly, and not on each individual chicken. He says that it is quite difficult for him to say takbeer on each chicken. We had read in one of Mufti Taqi Usmani Sahib's (db) book that according to Imam Shaafaee (Rehmat Ullah Alaih), it is sunnah to read takbeer during slaughtering. This is the only slaughter house in our knowledge where there is no machine slaughtering of chicken. Now my question is that, if person is slaughtering so many chickens, is it a MUST for him to pass takbeer on each individual. Is it possible for us to eat that chicken if that person is slaughtering correctly according to Fiqh Shafaee?