Elsevier

Journal of Veterinary Behavior

Volume 11, January–February 2016, Pages 56-59
Journal of Veterinary Behavior

Research
Effect of grazing muzzles on the rate of pelleted feed intake in horses

https://doi.org/10.1016/j.jveb.2015.10.001Get rights and content

Abstract

Esophageal obstruction or “choke” is a relatively common occurrence in equines. It often results from improper mastication, consuming feed too quickly, dehydration, or a decrease in saliva production. Esophageal obstruction is a medical emergency during which a horse cannot dislodge a bolus of feed from the esophagus and must wait for human intervention or for the block to be softened and moved by peristalsis. This condition may result in the formation of ulcers, esophageal rupture, aspiration pneumonia, and possibly death. Grazing muzzles have been shown to slow the rate of forage intake. We hypothesized that grazing muzzles could also be used to decrease the rate of pelleted feed intake and so possibly reduce the risk of equine esophageal obstruction in horses fed large meals of pelleted feed. The objective of this research was to compare the rate of pelleted feed intake for horses wearing grazing muzzles to those wearing no muzzle. Using a crossover design, horses were randomly assigned to 3 groups with each horse receiving each treatment. Treatments were as follows: no muzzle, easy breath grazing muzzle, or tough 1 nylon grazing muzzle. Eight adult stock-type horses aged 5 ± 1 years were offered 2.27 kg of pelleted concentrate to consume in a 10-minute period once daily. The study was comprised of 3 periods (5 days each) with a 2-day resting period between each. Horses were weighed daily and no significant change in bodyweight was observed. Data for daily intake were analyzed using the PROC MIXED procedure of SAS with significance established at P < 0.05. Both the easy breath grazing muzzle and the tough 1 nylon grazing muzzle reduced rate of intake (P < 0.05) during a 10-minute feeding interval as compared with no muzzle. The findings of this study revealed that grazing muzzles may be a viable option to reduce the rate of intake of pelleted feed, which may benefit horses susceptible to choke as a result of rapid feed ingestion.

Introduction

Equine esophageal obstruction, or “choke,” is a dangerous condition and the most common source of esophageal complications (Duncanson, 2006). Choke occurs when a bolus of foodstuff becomes lodged in the esophagus and must be removed either through the action of salivary lubrication, which is often inadequate, or human intervention (Hillyer, 1995). Choke is generally a result of improper or inadequate mastication, consuming pelleted feed too quickly (bolting), or insufficient salivary production (Kobluk et al., 1995). Signs of esophageal obstruction include dysphagia, excessive drooling, nasal drainage, coughing, halitosis, spasms of the neck muscles, and repeated swallowing (Hillyer, 1995). In addition, there may also be a visible mass in the throat area. Esophageal obstruction blocks the esophagus and prevents the passage of feed and liquid and, if present for long periods of time, can cause permanent damage to the esophagus. Damage due to choking includes esophageal ulcers, impaction colic, aspiration pneumonia, and potentially death (Kobluk et al., 1995). Treatment for choke is problematic as it involves insertion of a tube down the afflicted horse's throat and flushing out the bolus. This procedure can cause additional trauma to the esophagus and, in severe cases, surgical removal of the bolus may be necessary (Hillyer, 1995).

Because a majority of choke incidents are caused by rapid intake of feedstuff, decreasing the rate of intake and encouraging proper mastication is critical to prevent choke (Frape, 2008). Many horse owners use grazing muzzles to slow the intake of forages (Glunk et al., 2014a, Glunk et al., 2014b; Longland et al., 2011). We hypothesized that grazing muzzles could also be used to decrease the rate of pelleted feed intake and possibly reduce the risk of equine esophageal obstruction. The objective of this research was to compare the rate of pelleted feed intake for horses wearing 2 different types of grazing muzzle with those wearing no muzzle (NM).

Section snippets

Methods

Institutional Animal Care and Use Committee approval was obtained before the initiation of this study. All researches were conducted at Southern Illinois University Equine Center, Carbondale, Illinois. Eight Southern Illinois University–owned horses, 2 geldings and 6 mares, aged 5 ± 1 years (mean ± SD), and with a bodyweight of 491 ± 35 kg (mean ± SD), current with vaccinations and in good dental health were used. The grazing muzzles included the Easy Breathe Grazing Muzzle (EBM; JT

Results

Both the EBM and the TNGM grazing muzzles caused a decrease (P < 0.001) in rate of pelleted feed intake during the 10-minute feeding interval as compared with the NM treatment (Figure 1). Although there was no effect of day (P > 0.05), there was an effect of treatment × day interaction (P < 0.05). The authors have concluded that this interaction effect may be the result of a behavioral artifact associated with the NM group and their reduced intake on day 1. Student observers reported that the

Discussion

Ingesting feed too quickly, bolting, or improper mastication are common causes of choke. Grazing muzzles are commonly used to reduce forage intake rates (Glunk et al., 2014a, Glunk et al., 2014b, Longland et al., 2011). This is accomplished through slowing the consumption of forage by restricting the amount a horse can ingest (Longland et al., 2011). Utilization of a grazing muzzle while feeding pelleted feed was shown to reduce intake rate in this study. Subsequently, this may reduce the

Acknowledgments

All the research conducted in this original study was funded by Southern Illinois University. No external sponsors participated in funding. The idea for the study was conceived by Dr. Erin Venable. The experiments were designed by Dr. Erin Venable. The experiments were performed by undergraduate and graduate students named as coauthors on this article. The data were analyzed by Dr. Erin Venable and Stephanie Bland. The article was written by Dr. Erin Venable, Michael Halpin, and Stephanie Bland.

References (18)

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