Shannonside Foods Ltd denies the claims.
Alleged animal welfare abuses have been uncovered at Ireland's only licensed equine abattoir in Straffan.
Secretly filmed footage by RTÉ Investigates at Shannonside Foods Ltd claims to show routine mistreatment of horses before slaughter, including frequent beatings with a semi-rigid alkathene water pipe.
The Department of Agriculture oversees the meat plant but not the building where horses are kept before slaughter.
In 2023, around 2,000 horses were slaughtered at Shannonside Foods Ltd, two-thirds bred for racing.
Shannonside Foods Ltd denies the claims and states it takes legal responsibilities seriously, promising to investigate any allegations of mistreatment.
The Department of Agriculture stated it will investigate all evidence of illegal activity.
The RTÉ Investigates programme featuring the footage will be broadcast tonight at 9.35pm on RTÉ One.

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