Yoreh Deah Siman 19 Seif 5

 

ה אִם רוֹצֶה לִשְׁחֹט הַרְבֵּה, צָרִיךְ לִזָּהֵר שֶׁלֹּא לְדַבֵּר בֵּין שְׁחִיטָה לִשְׁחִיטָה בְּדָבָר שֶׁאֵינוֹ מִצָּרְכֵי הַשְּׁחִיטָה; וְאִם דִּבֵּר, צָרִיךְ לְכַסוֹת דַּם שְׁחִיטָה רִאשׁוֹנָה וּלְבָרֵךְ פַּעַם אַחֶרֶת עַל הַשְּׁחִיטָה, אֲבָל עַל כִּסוּי שֵׁנִי לֹא יְבָרֵךְ.  וְיֵשׁ אוֹמְרִים דְּשִׂיחָה בֵּין שְׁחִיטָה לִשְׁחִיטָה לָא הָוֵי הֶפְסֵק.

Seif 5

If one wants to slaughter many animals, he needs to be careful not to speak about things not related to ritual slaughter between the animals he has slaughtered.

If he did speak he needs to cover the blood of the first one he slaughtered and bless a second time on the slaughter. However on second covering (of blood) he does not make a second blessing. There are those that say that from the talk between slaughters, it is not an interruption.