ResearchEffect of grazing muzzles on the rate of pelleted feed intake in horses
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.
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