Gérard Clémente, who was boss of the Mauléon abattoir at the time of the offences in 2016, could have been jailed for up to two years and fined up to 300,000 euros.
But the court gave him a suspended sentence and a fine of just 180 euros for misrepresentation of product.
The four employees were fined between 80 and 910 euros for mistreating animals, the charge of cruelty, which could have led to imprisonment, having been dismissed.
The business was ordered to pay 10,000 euros to consumers' rights group Que Choisir.
In March 2016 animal rights and vegetarian campaigners L214 published a video showing mistreatment of animals that included a lamb being cut into quarters while still alive, sheep being bled while conscious and other animals insufficiently stunned when slaughtered.
The business, which employs 35 people, closed for two months after the revelations.
Another animal rights group, Animal Cross, slammed the verdicts as inadequate.
A lawyer for three of the employees, Antoine Tugas, praised them for "putting aside dogmatism", while the abottoir's lawyer, Denise Pombieilh, called them "pretty moderate and fair".
Clémente argued in court that it was difficult to recruit well-trained personnel, given that no specific training exists.
The employees said the company was understaffed at the most busy times, provided inadequate tools and gave insufficiently detailed instructions.