Please cite this article in press as: Albright, J., et al., Does cribbing behavior in horses vary with dietary taste or direct gastric stimuli? Appl. Anim. Behav. Sci. (2017), http://dx.doi.org/10.1016/j.applanim.2017.01.015 ARTICLE IN PRESS G Model APPLAN-4402; No. of Pages 5 Applied Animal Behaviour Science xxx (2017) xxx–xxx Contents lists available at ScienceDirect Applied Animal Behaviour Science journal homepage: www.elsevier.com/locate/applanim Does cribbing behavior in horses vary with dietary taste or direct gastric stimuli?  Julia Albright a,∗ , Xiaocun Sun b , Katherine Houpt a a College of Veterinary Medicine, Cornell University, 602 Tower Road, Ithaca, NY 14853, USA b Office of Information Technology, University of Tennessee, 821 Volunteer Boulevard, Knoxville, TN 37996, USA a r t i c l e i n f o Article history: Received 14 June 2016 Received in revised form 30 January 2017 Accepted 31 January 2017 Available online xxx Keywords: Horse Stereotypy Cribbing Diet a b s t r a c t Concentrated feed diets have been shown to drastically increase the rate of the cribbing, an oral stereotypy in horses, but the specific component causing the rise has not been identified. Furthermore, the mecha- nism through which feed affects cribbing has not been explored. In the first experiment of this study, we quantified the latency to crib and number of cribs in 15 min after the horses tasted various grain, sugar, and artificial sweetener solutions. Undiluted grain stimulated the most cribs (P < 0.01) compared with all other solutions, and shortest latency to crib, although this was significantly higher only when compared with diluted grain (P = 0.03). In Experiment 2, latency to crib and number of cribs in 15 min after the grain and sugar solutions were administered via nasograstric tube were also evaluated. There were no statistical differences among cribbing responses to grain, fructose, and water administered directly to the stomach although grain stimulated cribbing behavior more quickly than 10% fructose (P = 0.03) and 100% tap water (P = 0.04). These results confirm that highly palatable diets, possibly mediated through the opioid and dopaminergic systems, are one of the most potent inducers of cribbing behavior. The highly palatable taste remains the probable “cribogenic” factor of concentrated diet, although gastric and post-gastric effects cannot be excluded. © 2017 Elsevier B.V. All rights reserved. 1. Introduction Stereotypies are abnormal repetitive, invariant, and seemingly functionless behaviors, and these behaviors are associated with suboptimal environmental conditions, although the exact causal factors remain unknown (Mason, 1991). Cribbing, or crib-biting, is an equine oral stereotypy characterized by a horse placing its upper incisors on a horizontal surface and drawing air into the esopha- gus while flexing the ventral neck muscles (McGreevy et al., 1995). The prevalence of the behavior has been estimated to be around 2–10%, with some breeds demonstrating a predisposition for crib- bing (Albright et al., 2010; Bachmann et al., 2003; Luescher et al., 1998; Vecchiotti and Galanti, 1986). Management practices related to social contact, pasture time, and high-concentrate diet have also been linked to the performance of cribbing (reviewed by Wickens and Heleski, 2010).  This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. ∗ Corresponding author. Present address: College of Veterinary Medicine, Univer- sity of Tennessee, 2407 River Drive, Knoxville, TN, 37996, USA. E-mail address: jalbrig1@utk.edu (J. Albright). Provision of concentrated feed to young horses at weaning is a particularly strong risk-factor for the development of cribbing (Waters et al., 2002). Sweet feed is also known to increase the rate of cribbing immediately post-ingestion in established crib- bing horses (Kusunose, 1992). Consuming roughage (Gillham et al., 1994) and plain oats (Whisher et al., 2011) does not have the same crib-inducing effect. Some hypothesize that highly palatable diets induce the release of endogenous opioids and, in turn, cribbing through a complex interplay of the opioid, dopaminergic, and glu- taminergic neural systems (Dodman et al., 1987; Gillham et al., 1994). The goal of this study was to characterize further the rela- tionship between sweet-tasting substances and cribbing. The first objective was to compare the effects of sugars, artificial sweet- ener, and sweet feed ingested by mouth on cribbing behavior. We measured the number of cribs and latency to crib as indicators of the strength of motivation to crib. We hypothesized that the taste of food influenced cribbing rate and predicted the commercial sweet feed would be the strongest stimulator of cribbing, followed by sucrose and fructose solutions. The second objective was to compare cribbing after delivery of a single-sugar or grain solution directly to the stomach via nasogastric tube. We hypothesized that some aspect of taste, such as neurophysiologic mechanisms associ- http://dx.doi.org/10.1016/j.applanim.2017.01.015 0168-1591/© 2017 Elsevier B.V. All rights reserved.