Equine experts widely advocate pasture access for maximizing the health of horses with heaves,osteoarthritis, or simply to match their “evolutionary upbringing,” so to speak. Although beneficial in many ways, putting horses on 24-hour turnout, which occurs in many parts of the world, is a double-edged sword, according to one research group*.
“Such management may be perceived as being ideal, enabling the animal to graze freely, exercise, and engage in social behavior on the one hand, and requires relatively little labor input from the owner, on the other. However, for animals in receipt of minimal structured exercise, constant access to pasture can lead to weight gain and obesity. Indeed, at certain times of year, such improved pastures contain herbage with an energy value that is equal to or exceeds that of a high-energy compound feed.”
One potential method of controlling weight gain while on pasture involves using a grazing muzzle. The problem is, however, there is still some question regarding the efficacy of such devices. To help determine if a grazing muzzle is a realistic solution, Longland and colleagues recruited nonobese ponies and placed them on pasture for 23 hours per day. Ponies were allowed to either graze freely or were muzzled for 10 hours daily. Changes in body weight (expressed as percent change in body weight) were assessed.
Researchers found that ponies allowed to free graze gained significantly more weight than muzzled ponies. Not a surprise, right? But there’s more to the story.
“It is important to note that this study also found that not all horses responded similarly to the grazing muzzle, and one muzzled pony gained almost the same amount of weight as the ponies included in the free-graze group. Also, researchers determined there is a learning curve when using the grazing muzzle for animals that have never worn one before,” relayed Kathleen Crandell, Ph.D., an equine nutritionist forKentucky Equine Research.
Based on this study, owners could consider grazing muzzles to help avoid obesity, which can easily be monitored using the Henneke body condition score chart.
*Longland, A.C., C. Barfoot, and P.A. Harris. Efficacy of wearing grazing muzzles for 10 hours per day on controlling bodyweight in pastured ponies. Journal of Equine Veterinary Science. In press.