No abstract

The spontaneous behaviour and the apparent digestibility of dry matter and fibre and transit times of digesta were compared in four normal horses and four crib-biters. A technique was developed for measuring total gut transit times (TGTT) by using single-stool analysis of the passage of radio-opaque polyethylene markers. Longer TGTT were recorded in the crib-biters than in the normal horses but the orocaecal transit times did not differ. The crib-biters rested less than the normal horses.

Summary Crib‐biting is a common oral stereotypy. Because of perceived deleterious effects on the health and appearance of subjects the prevention of crib‐biting is regularly attempted. The resourcefulness of horses in satisfying their motivation to perform this behaviour often frustrates owners' efforts at prevention. This paper reviews the efficacy and observable consequences of attempting to prevent crib‐biting by a variety of methods. These include attempts to prevent the grasping of objects, to interfere with air‐engulfing and to introduce punishment for grasping and neck‐flexion. Other approaches include the use of surgery, acupuncture, pharmaceuticals, operant feeding and environmental enrichment. A remedy that is effective for every crib‐biter remains elusive. We conclude that, rather than concentrating on remedial prevention, further research should be directed at establishing why horses crib‐bite and how the emergence of crib‐biting can be avoided.

Summary The results of an experimental study of the motivational consequences of short‐term prevention of crib‐biting are reported here. Eight test horses wore a cribbing collar for 24 h. This was effective in preventing crib‐biting in 6 subjects. Using analysis of co‐variance that accounted for baseline differences in crib‐biting rate, test horses showed significantly more crib‐biting than control horses on the first day after prevention (P < 0.05). There was also a highly significant increase in the crib‐biting rate of test horses on the first day after prevention in comparison with their baseline rate (P < 0.01). This defines the increase as a post inhibitory rebound. An increase in the novelty of the cribbing bar and an increase in feeding motivation during the period of prevention are rejected as explanations of the rebound in this study. Instead, it is suggested that the rebound reflected a rise in internal motivation to crib‐bite during the period of prevention. Behaviours that exhibit this pattern of motivation are generally considered functional; and it has been argued that their prevention may compromise welfare.