109 The effect of wearing grazing muzzles for 10 hours daily on bodyweight of ponies pastured for 24 hours per day

Abstract

s / Journal of Equine Veterinary Science 35 (2015) 418e436 430 109 The effect of wearing grazing muzzles for 10 hours daily on bodyweight of ponies pastured for 24 hours per day A.C. Longland*, C. Barfoot , and P.A. Harris 3 1 ELNS, Tregaron, Ceredigion, Wales, UK; Mars Horse Care UK Ltd., Old Wolverton, Buckinghamshire, UK; Waltham Centre for Pet Nutrition, Waltham-on-the-Wolds, Leicestershire, UK Obesity in equids can increase the risk of several metabolic disorders, including insulin resistance and laminitis. Moderating bodyweight in pastured equids can be difficult but restricting grazing time, confinement to small, bare paddocks and use of grazing muzzles during limited turnout periods are potentially effective. However, some owners keep their animals at pasture 24/7 and may be unable to implement such strategies, or favor permanent pasture turnout in large paddocks providing greater opportunities for exercise and social interaction. Wearing grazing muzzles during 3 h turnout has previously been shown to significantly reduce herbage intakes by ponies vs. grazing unmuzzled for the same period, but the effect on 24 h total intake was not determined. This study investigated the effect on pony bodyweight of wearing grazing muzzles for 10 h per day followed by un-muzzled access to the same summer pasture for the rest of the day. Ponies were adapted to grazing and drinking through their grazing muzzles before the study. The study was a crossover design, of two 3-week periods. Four ponies were split into pairs, A and B. In period 1, pair A wore grazing muzzles from 0800 h until 1800 h, followed by un-muzzled grazing until 0800 h the next day and pair B grazed the same pasture for the entire period un-muzzled. In period 2, pairs A and B switched treatments. On alternate days ponies were weighed at 0730 and 1800 h. Ponies received the same individual light exercise 3 times per week. Data were subjected to paired t-tests. When not muzzled, ponies averaged weight gains of nearly 0.3 (±0.098) percent of bodyweight per day which was significantly different (P < 0.05) from the average losses of 0.04 (±0.11) percent of bodyweight per day exhibited by the same ponies when muzzled for 10 h per day. However, there was considerable inter-animal variation in response to wearing grazing muzzles with one gaining small amounts of weight when muzzled, albeit to a lesser degree than when un-muzzled. A fifth pony, that was removed from the trial after being on treatment ‘muzzled’ for 3 weeks, gained weight at a rate 1⁄4 those grazing the same pasture without a muzzle. Additionally, one pony became progressively resistant to wearing a grazing muzzle, spending extended periods resting rather than grazing when muzzled. Thus, this study demonstrated that use of grazing muzzles for 10 h per day can be a successful strategy for controlling bodyweight increase in some, but not all ponies at pasture for 24 h per day.