Does unlimited access to hay deter crib-biters?
04 Dec 2015
Scientists in the UK have performed a study to see if the provision of unlimited hay or a mineral lick in stabled crib-biting horses could reduce their display of this stereotypic behaviour. Crib-biting occurs whereby the individual grips wood with their teeth, such as the stall door, and sucks in air. It is believed that crib-biting releases the pleasure neurotransmitter dopamine in the brain and it is thought that this stimulus acts as a reward for crib-biting horses and causes them to become addicted to the behaviour. Crib-biting commonly occurs in stabled horses and is thought to be a coping mechanism for dealing with the stress of an unnatural environment such as limited freedom of movement and limited access to forage. Feral horses do not show crib biting behaviour.
Other studies have also shown that reducing the percentage of roughage in the diet or increasing the percentage of concentrated feeds such as grain can increase crib biting.
Crib-biting is seen as an undesirable habit, as it can cause wear of the front teeth, destroy fences and stables and is thought to lead to a higher risk of colic.
Eight horses were observed in the study, four were crib-biters and four were not. The horses were subject to four different diets: unlimited hay with a mineral lick, rationed hay with a mineral lick, unlimited hay with no mineral lick and rationed hay with no mineral lick. The hay was rationed as required by the horses’s body weight. Each horse was observed for half an hour three times daily for two days on each diet.
The results indicated that the provision of a mineral lick or unlimited access to hay did not deter the test subjects from crib-biting. The horses did not eat or crib-bite any less when fed an appropriate ration of hay for several days versus being offered unlimited hay for several days. Nor was there any significant difference when offered a mineral lick versus no mineral lick. The scientists observed that the crib-biting horses switched behaviour (eg. Sleeping, resting, eating, crib-biting) more than forty times as much compared to control horses in the study whom were not crib-biters.
There has also been some evidence to support that crib-biting may be genetic. A 2009 study in the US found that Thoroughbreds were more than twice as likely to crib-bite than other breeds. Of course, this could also be because Thoroughbreds are more likely to be stabled from a young age compared to other breeds, and being stabled is usually the environment that triggers crib-biting.
Does your horse crib-bite? Do you find it a problem?
Moore-Colyer, M. J. S., Hemmings, A., & Hewer, N. (2015). A preliminary investigation into the effect of ad libitum or restricted hay with or without Horslyx on the intake and switching behaviour of normal and crib biting horses. Livestock Science.