After transportation, animals are usually kept in lairage (holding pens) for a period before being slaughtered. One purpose of lairage is to maintain a reserve of animals so that the processing line in the abattoir can operate at a constant speed and not be affected by variation in the rate of delivery of livestock. When lairage conditions are good it also gives animals a chance to rest and drink.

Lairage times vary widely — from less than an hour to twenty or more hours. Optimal resting time before slaughter depends on climate, the time spent by the animals in transit, the mode of transport, the general health of the animals, and the design of the lairage.
Herringbone lairage for pigs in a big slaughter house. Photo: Temple Grandin