b'REAL-WORLD RESEARCHWelfare-Friendly Weight-Loss Tools? they were working harder for their grass. Minis muzzled for 24 hours had lower heart rates and greater heart Research has shown grazing muzzles can reduce forage intake byrate variability (changes) than the others.30-83%. But covering a horses lips and nostrils can affect grazingThere was no difference between treatment groups salivary cortisol habits and mask body language. Amy Burk, PhD, associate professorlevels, which Burk said was surprising.at the University of Maryland, in College Park, along with her graduateNext, Burk and Davis used the same design, but group-housed the student Kristina Davis recently conducted a study to find out howMinis in a field to assess their voluntary exercise, hierarchy, and weight muzzles affect social behavior and stress levels.loss with and without grazing muzzles. They used a GPS tracking device In the first phase of their study, Burk and Davis used six Miniatureto determine how far the Minis traveled and found that:Horses turned out 24/7 in quarter-acre grass paddocks. They rotated Minis muzzled for 24 hours lost, on average, 1.1 pounds, while the two Minis at a time through three 21-day treatment periods: no muzzle,other two groups gained, on average, 3.3 pounds. Compensatory muzzled for 10 hours per day, and muzzled for 24 hours per day. grazing after muzzles were removed may explain weight gain experi-Davis took videos of the Minis behavior and measured their bodyenced by those muzzled for 10 hours, said Burk.weight, body condition score, cresty neck score, and girth circumferenceAll Minis walked approximately 6.4 kilometers (4 miles) per day at the beginning and end of each study period. She also gave eachbecause they functioned as a herd, she said;Mini a muzzle acceptability score on a scale of 1 to 5, with 1 indicating Minis muzzled for 24 hours stood the most, while unmuzzled Minis acceptance and 5 rejection. She measured heart rate and salivarytrotted and cantered the most;cortisol levels as indicators of stress. Burk and Davis found that:Unmuzzled Minis autogroomed (self-groomed) most; Minis muzzled for 24 hours lost weight but didnt experience any Muzzled Minis couldnt perform normal hierarchy behaviors or bite. other physiological changes. Dominance rank, however, didnt change, said Burk. Muzzled Minis didnt exhibit stereotypies or frustration behaviors. Wearing grazing muzzles for 10 or 24 hours doesnt induce stress orUnmuzzled Minis spent more time mutually grooming than muzzledaffect voluntary exercise but does alter behavior, she concluded.Minis. Muzzling for 24 hours was a good way to prevent weight gain andMinis muzzled for 10 hours rested more and grazed less than thedidnt impose on welfare, said Burk. In fact, it might have a cardiovas-other two groups. cular benefit. She and Davis theorized that the muzzled Minis constantMinis muzzled for 24 hours grazed more and rested less, indicatingforaging might have a calming effect, as evidenced by lower heart rates.a rule of thumb, he adds, horses shouldfluid fluxes through the tract, essen- post-foaling. Blikslager hypothesized respond to the first round of NSAIDtially dehydrating and rehydrating thereasons for this: the big physiological treatment. If they need a second round,large intestine repeatedly, which canchanges that take place right after foal-the vet should discuss with the ownerput horses at risk of colon impaction. ing (i.e., more space in the abdomen); referral to a hospital. 6. On average, food travels 20 meterssignificant changes in exercise levels as 3. The major themes in colic prevention(about 65 feet) through the horsesmares are stalled to foal, then turned revolve around feeding (forage typestomach and small intestine andback out; nutritional changes during and quality) and management (mealinto the cecum and large colon fairlylactation; and microbiome changes. frequency, parasite control, housing,rapidlywithin two to three hours.He said this latter cause is a promising etc.). Managing these can help preventThis means concentrate feeds enterfuture research focus.colic in the future, said Blikslager. the colon relatively undigested, saidIn sum, Blikslager said owners and 4. Colic prevalence is sometimes associ- Blikslager, triggering microbiome (theveterinarians must learn to better recog-ated with horses consuming coastaltotality of microbes, their genomes,nize horse colic risk factors (e.g., foaling, Bermuda hay. A 2002 study foundand interactions in an environment)hay type, etc.) and focus on management horses fed this hay were six times morechanges and those large fluid fluxes. changes such as feed quality to pre-likely to develop ileal impaction than7. Psyllium is a popular daily supplementvent the condition. Researchers should horses fed other grass hays. for preventing sand colic in horsescontinue to study the significance of the Blikslager presented one theory asthat graze on sandy soils. In theorymicrobiome and refine optimal feeding to why, emphasizing it hasnt yet beenit reduces sand levels in the gut, butand turnout management practices.proven: Coastal hay is much finer,Blikslager said it might act more like stemmier hay. If horses arent used toa prebiotic, which gets digested by theUnderstanding Equine Locomotionit, they dont chew it properly and unin- microbes within the colon. This could,Horses generate ground reaction forces tentionally swallow longer fibers thanin turn, result in increased levels of(GRF) when they set their hooves on the they should. This can clog the ileocecalshort-chain fatty acids, which mightground to produce movement. One world-junction like hair in a drain. have positive effects on the microbiomerenowned researcher in equine locomo-5. A horse passes approximately 150and gut motility, thereby speeding sandtion and biomechanics says recognizing liters, or 40 gallons, of fluid through hispassage. these invisible forces is key to understand-gastrointestinal tract each day. Meal8. Broodmares are at risk of largeing how horses travel and compensate for feeding, in particular, causes massiveintestine strangulating obstructionslameness. Hilary Clayton BVMS, PhD, 22October 2019The Horse | TheHorse.com'