Beverly Gartland, graduate student at Western Kentucky University, in Bowling Green, aimed to find out. She presented her findings at the 2019 Equine Science Society Symposium, held June 3-6 in Asheville, North Carolina.
In her study, Gartland evaluated eight adult horses with maintenance-level nutrient requirements and similar body condition scores. She randomly placed four in a continuous grazing group (six weeks on a 2.2-acre tall fescue field) and four in a space-restricted rotational grazing group. Every seven days, she’d move the latter group into a new 1/3- to 1/10-acre grazing cell with only enough grass to meet 80% of their daily nutrient requirements.
Each week Gartland would bring all horses inside, fast them overnight, and take their weights. Three times a week, she observed and recorded how much time each horse spent grazing, standing, or performing other behaviors.
At the end of her study, Gartland found that the restricted grazing group maintained or lost body weight, while the continuous grazing group gained significant weight.
“Overall, both groups spent most of their time (76%) grazing, but as pasture size was further restricted in the space-restricted rotational grazing group, the horses spent more time standing and less time grazing,” she said. “The reverse happened for the continuous grazing group.”
Therefore, she said that in addition to having less available forage, factors such as the social dynamics of crowding likely influenced grazing behavior in this group of horses.
Horse owners might be able to rotate horses at risk of obesity through smaller pasture spaces to prevent them from gaining weight. You can create these cells using temporary fencing. An added bonus? It’s an effective solution for small acreage facilities, benefits your pastures, and prevents overgrazing.