The Effect of Ad Libitum Concentrate Feeding on Crib-Biting Behavior in the Horse
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Previous research indicates cribbing behavior in horses increases when horses were fed concentrate meals. This study used 10 mature cribbing geldings to investigate effects of ad libitum concentrate feeding on cribbing behavior. Horses were randomly assigned to either ad libitum feeding (n=5) or control (n=5) groups and were maintained on Bermuda grass (Cynodon dactylon) pasture and free choice hay. Each horse received a baseline ration of 1.8 kg of a commercially available pelleted concentrate twice daily at the start of the study (d 0). Control horses remained on this amount throughout the study. Feed for ad libitum horses was increased to approximately 3.6 kg concentrate four times daily and maintained at this amount for 102 d. Ad libitum horses were then fed 0.9 kg concentrate four times daily (d 103-136) and finally returned to baseline ration (d 137-170). Numbers of crib bites, crib bouts and duration of crib bouts were recorded for all horses during six 24 h observation periods (d 0, 28, 66, 102, 136 and 170). Data were analyzed as a repeated measures design. A significant treatment by observation day interaction was revealed for crib bites (P > 0.01), total crib bouts (P > 0.001) and bout duration (P > 0.01). Preplanned contrasts showed that control horses performed an average of 2012 ± 495 more crib bites (P > 0.01), 3.9 ± 1.6 more crib bouts (P > 0.01) and spent 13988 ± 2922 s more time cribbing (P > 0.001) than ad libitum fed horses during the ad libitum feeding period. When ad libitum fed horses were fed normal feed amounts four times daily (d 103-136), their total crib bites, total crib bouts and duration of crib bouts were not significantly different from control horses. Also, no significant residual effect of ad libitum feeding on cribbing behavior was found when ad libitum fed horses were returned to baseline feeding levels (d 137-170). It is not clear from this study whether the decrease in cribbing behavior seen in the ad libitum fed horses was the result of additional feed or a change in other factors that accompany concentrate feed delivery. Additionally, ad libitum feeding cannot be considered a viable method to reduce cribbing behavior because of possible negative effects, such as obesity, of this feeding regimen on horse health and usefulness.