This behavior may be tied to feeding or digestion, instead of stress or boredom.
Cribbing is a repetitive behavior where the horse places its upper incisors against a horizontal surface, arches its neck, pulls backwards with its body and may produce a characteristic grunting sound. The digestive process of cribbing horses may differ from horses that do not crib because cribbing horses have lower gastric pH than normal horses, produce less saliva, have slower orocecal transit times and greater incidence of stomach ulcers and particular types of colic than non-cribbing horses.
Cribbing frequency also increases around concentrate meal feeding times. It is not known if this increase in cribbing behavior is due to the ingestion of the feed itself or whether factors, such as activity levels, diurnal rhythms or digestive physiology might be involved. A recent study at Auburn University was initiated to determine if cribbing activity was correlated to concentrate intake.
Initial analysis indicated that the majority of cribbing activity in this study occurred around the feeding times as previously reported, and higher values were observed during the time period corresponding more closely to concentrate feeding times.
There are many theories as to the cause of cribbing behavior. Stress reduction, isolation or lack of social interaction, genetics, altered digestive or neural physiology have been hypothesized as origins of this behavior. Though the present results do not eliminate these possible causes, they may direct further study around theories that highlight feeding or digestive causes of cribbing. The current study showed that the highest frequency of cribbing behavior followed times of concentrate feeding.
These data suggest that the function of cribbing does not lie in stress reduction or easing boredom, but support the claim that the behavior may be tied to feeding or digestion.