The fuqaha’ are unanimously agreed that part of the etiquette of slaughtering is not to slaughter one animal in front of another.
See: al-Mawsoo‘ah al-Fiqhiyyah, 10/221
This is part of the beauty of Islam with its mercy and kindness and good manners.
Ibn Qudaamah (may Allah have mercy on him) said:
It is makrooh to slaughter one sheep when another is looking on. End quote.
And it says in ‘Awn al-Ma‘bood:
He should not handle it violently, or drag it to slaughter violently, or slaughter it in the presence of another.
Shaykh Ibn Baaz (may Allah have mercy on him) said:
It is makrooh to slaughter (an animal) when another is looking on. End quote.
Majmoo‘ Fataawa Ibn Baaz (23/73-74)
Shaykh ‘Abd al-Muhsin al-‘Abbaad said:
He should not slaughter it with a tool or cause pain to it as he is slaughtering it. Also he should not slaughter it in front of another, because this is torture. End quote.
Sharh Sunan Abi Dawood, 14/212
If one animal is slaughtered in front of another, this does not mean that eating its meat is haraam, if the slaughter is done in the proper Islamic manner, because all he has done thereby is something makrooh, and such actions do not make the meat haraam.
With regard to slaughtering animals together in front of one another, as is the case in mechanised slaughterhouses, there is nothing wrong with it, because one animal does not see another when it is being slaughtered; rather they are all slaughtered at the same time with one movement of the machine.
The scholars of the Standing Committee for Issuing Fatwas said: It is permissible to slaughter animals using modern machines so long as the blades are sharp and they cut the throat and the windpipe.
If the machine slaughters a number of chickens at one time, then it is acceptable to mention the name of Allah once by the one who is operating the machine when he starts it, with the intention of slaughtering, so long as the person who is operating the machine is a Muslim or a kitaabi (i.e., a Christian or a Jew). End quote.
Fataawa al-Lajnah al-Daa’imah, 22/463.
And Allah knows best.