Reference for Chullin 57:6

ת"ש

and if an exact half is not equivalent to the greater portion then he has done nothing at all [which would render the slaughtering invalid].<span class="x" onmousemove="('comment',' And his having cut half of the windpipe is of no consequence for the bird would not be rendered trefah thereby; v. infra 44a-b.');">³</span>

Jastrow