Yoreh Deah Siman 23 Seif 5

ה אַחַר שֶׁשָּׁחַט רֹב אֶחָד בְּעוֹף אוֹ רֹב שְׁנַיִם בִּבְהֵמָה, אֵין שְׁהִיָּה פּוֹסֶלֶת; וּלְפִי זֶה אֵין שְׁהִיָּה בַּקָּנֶה בְּעוֹף כְּלָל. וְיֵשׁ מִי שֶׁאוֹמֵר שֶׁכָּל שֶׁלֹּא נִגְמְרָה שְׁחִיטַת כָּל שְׁנֵי הַסִימָנִים, פּוֹסֶלֶת שְׁהִיָּה; וּלְכַתְּחִלָּה יֵשׁ לִזָּהֵר לָחוּשׁ לִדְבָרָיו.

 

Seif 5

 

After one slaughters most of one [sign] in fowl, or most of two [signs] in cattle, there is no “shehiyah” that can make it [the slaughter] not acceptable. Accordingly there is not “shehiyah” with the windpipe in fowl. But there are those that say that in any place that one does not finish the slaughter of both signs it [the slaughter] is not acceptable on the grounds of “shehiyah”, and ab initio they should take heed and be concerned about this..