Short Communication
Interaction of Grazing Muzzle Use and Grass Species on Forage Intake of Horses

https://doi.org/10.1016/j.jevs.2014.04.004Get rights and content

Abstract

The impact of horse preference and grass morphology on grazing muzzle effectiveness has not been investigated. The objective of this study was to determine the effectiveness of grazing muzzle use at reducing forage intake when horses grazed grasses with different morphology and preferences. The study was conducted in 2012 and 2013. Four horses were grazed in 2012, and three horses were grazed in 2013. Four species of perennial cool-season grasses were grazed in 2012 including Kentucky bluegrass (Poa pratensis L.), meadow fescue (Schedonorus pratensis Huds.), perennial ryegrass (Lolium perenne L.), and reed canarygrass (Phalaris arundinacea L.). In 2013, only Kentucky bluegrass and reed canarygrass were grazed because of winter kill of other species. Horses were allowed to graze a small pasture seeded with an individual species for 4 hours each day in June and August of 2012 and August and September of 2013. Horses grazed the same grass species for two consecutive days, one day with a muzzle and one day without. Before and after each grazing, a strip was mechanically harvested to determine initial and residual herbage mass. The difference was used to estimate forage intake. The effectiveness of a grazing muzzle was not affected by forage species (P ≥ .05). Use of a grazing muzzle decreased the amount of forage consumed by an average of 30% compared with not using a grazing muzzle (P < .0001). Results will aid horse owners and professionals in estimating forage intake of muzzled horses on pasture.

Introduction

Recent research has shown that 21%, 19%, and 14% of horses in the United Kingdom [1], New York [2], and Minnesota [3], respectively, were considered “fleshy” with a body condition score [4] of ≥7. In an attempt to reduce horse body condition, owners have sought to restrict forage intake by a number of methods, including eliminating or decreasing the amount of time on pasture; however, restricted grazing is not always effective. Glunk et al [5] found that horses were able to increase their dry matter (DM) intake rates with restricted grazing time.

Many horse owners are in need of management strategies that restrict pasture intake while maintaining a horse's natural environment. In recent years, the use of grazing muzzles has gained popularity because its use limits forage intake while still allowing turnout, exercise, and socialization in an outdoor setting. Longland et al [6] found that use of a grazing muzzle reduced forage intake by 83% when ponies grazed an autumn pasture with a sward height of 8–15 cm. However, horses are known to be selective grazers, which may affect the effectiveness of a grazing muzzle. Allen et al [7] determined that horses preferred Kentucky bluegrass (Poa pratensis L.) and meadow fescue (Schedonorus pratensis Huds.), whereas exhibiting less preference for reed canarygrass (Phalaris arundinacea L.) and perennial ryegrass (Lolium perenne L.). Researchers have observed that grass morphology, or growth type, also affected livestock forage preference [8]; however, it is unknown if horse preference and forage morphology will impact the effectiveness of a grazing muzzle. Therefore, the objective of this research was to determine the effectiveness of grazing muzzle use at reducing forage intake when horses grazed grasses with different morphology and preference.

Section snippets

Horses, Forage, and Sampling

All experimental procedures were conducted according to those approved by the University of Minnesota Committee on Animal Use and Care. On August 8, 2011, six replicated plots measuring 3.3 × 6.7 m were planted. Grass species included “Ginger” Kentucky bluegrass, “Remington” perennial ryegrass, “Pradel” meadow fescue, and “Palaton” reed canarygrass. Kentucky bluegrass and meadow fescue were previously determined to be highly preferred, whereas perennial ryegrass and reed canarygrass were

Results

Average percentage initial herbage mass consumed and percentage reduction in year 1 (2012) is shown in Table 1. There was no effect of species (P = .27) on initial herbage mass consumed. Although a wide range in consumption values were observed both with (22%–49%) and without (47%–79%) a grazing muzzle, consumption was not different among the forage species. This was likely because of natural variability in forage height and density found within the plots. However, average initial herbage mass

Discussion

The use of a grazing muzzle decreased the percentage of initial herbage mass consumed across all species, except reed canarygrass in year 1. Allen et al [7] found that reed canarygrass was less preferred by grazing horses compared with other cool-season grasses which likely contributed to the similar initial herbage mass consumed both with and without the use of a grazing muzzle in year 1. Another possible contributing factor was the morphology of reed canarygrass. Reed canarygrass has an

Conclusions

The use of a grazing muzzle reduced adult horse's pasture intake by approximately 30%, regardless of cool-season grass species grazed. The use of a grazing muzzle appears to offer a simple, affordable, and effective management strategy for restricting forage intakes of grazing horses. Results will be useful in helping horse owners, veterinarians, and nutritionists estimate forage intake of muzzled horses on pasture and will be useful in developing more accurate rations for muzzled horses.

Acknowledgments

This study was funded by the University of Minnesota Equine Center with funds provided by the Minnesota Agricultural Experiment Station and Minnesota Racing Commission.

Cited by (14)

  • Nutritional Considerations When Dealing with an Obese Adult Equine

    2021, Veterinary Clinics of North America - Equine Practice
  • Effects of grazing muzzles on behavior and physiological stress of individually housed grazing miniature horses

    2020, Applied Animal Behaviour Science
    Citation Excerpt :

    It is unclear whether muzzling for shorter intervals may mitigate these potential animal welfare issues. While many studies have been conducted on grazing muzzle efficacy (Glunk and Siciliano, 2011; Glunk et al., 2014; Longland et al., 2011, 2016a,b; Venable et al., 2016), no studies to the author’s knowledge have been conducted on how grazing muzzles affect horse behavior as it relates to welfare. Therefore, the objective of this study was to evaluate the effects of continuous muzzling or muzzling for the minimum recommended time on behavior and physiological stress in individually housed grazing miniature horses.

View all citing articles on Scopus
View full text