Spring grazing is often associated with laminitis concerns for many area horse owners. Cool season grasses (such as fescue) are most often the culprit in pasture-associated laminitis cases because the sugar these grasses store during photosynthesis isn’t self-limiting. Depending on environmental conditions, non-structural carbohydrates (NSC’s) can accumulate in the plant. Excess accumulation of NSC’s can occur when cool nighttime temperatures restrict the plant’s ability to utilize the sugar made and stored during the warm, sunny days (conditions that occur in spring and fall).
For horses considered high-risk for developing laminitis, such as those that are easy keepers, overweight, are insulin resistant, or have Cushings, grazing fescue or other cool-season forages may need to be avoided all together in spring and fall. Both grazing muzzles and dry lot turnout may be options to reduce forage consumption in these horses, while still allowing for exercise. Feeding a lower calorie/mature hay before turn-out could also help prevent horses from gorging. It’s important to monitor body condition in these at-risk horses to prevent excess weight gain. This can be done by recording a BCS score or weigh tape reading monthly.
Although encouraging pasture growth may seem counter-intuitive, proper pasture
management is important to reducing NSC content in these forages. Overgrazed pastures expose the base of the plant, where most of the NSC is stored, to grazing horses. Maintaining pastures in a state of growth, with proper fertilization and by maintaining a height of at least 4- 6 inches is a good practice to reduce forage NSCs.
Well-maintained pastures can be an excellent resource, reducing feed and hay costs, providing much-needed free exercise for your horse(s), and reducing pollution from run-off. Many young horses, those that are lean and fit, and many without any previous laminitis episodes can graze safely in the spring, but remain aware of any changes in behavior or weight gain.
Feet of grazing horses can also be monitored for heat and/or a digital pulse, indicating a potential laminitis episode. Horses that have been on pasture 24/7 throughout the winter generally adapt as the pasture composition gradually changes. If you’re introducing a horse to a new pasture or if grazing has been limited through the winter, start by allowing the horse to graze for one hour then increase by 30 min every few days until a total time of four hours is reached. Grazing should be initiated early in the morning, when NSC content is the lowest. Pasture NSC builds throughout the day as the plant carries out photosynthesis; therefore, early morning hours, right before sunrise is when daily NSC concentrations are lowest. If you suspect your horse may be insulin-resistant, consult with your veterinarian. Feel free to contact me at the Extension Office at 828-894-8218 or by email Cassie_LeMaster@ncsu.edu with questions or if you need assistance designing a grazing plan that is best for your horse.
