Motivation for cribbing by horses
The motivation to crib was compared to the motivation to eat. Eight horses (Equus caballus) were operantly conditioned to push a switch for the opportunity to crib. When a progressive ratio was imposed, they worked as hard for a cribbing opportunity as for the opportunity to
eat sweetened grain indicating a high demand. Another measure of motivation is the effort expended by the animal. The force exerted when a horse cribs was measured by attaching weights to a door and observing how heavy the weights had to be to prevent the horse from pulling a door toward itself
when it cribbed. Seven horses were tested. Each neck flex of a crib-biting action was forceful enough to lift 29.4 (± 5) kg. The motivation to crib and the force involved indicates that thwarting cribbing is a welfare issue.