Pasture Management Recommendations

Carbohydrate research done on forages, although not specific to carbohydrate type, has provided information on pasture management that owners can use to manage their horses' intake of carbohydrates. This is particularly of interest to owners with laminitic and/or Cushingoid horses. Kathryn Watts of Rocky Mountain Research and Consulting, a leading equine forage researcher, offers the following recommendations for managing pastures to keep non-structural carbohydrates (NSC) lower in pasture grass.

"Growing grass with optimum amounts of water and fertilizer will help keep non-structural carbs from accumulating," explains Watts. "Some people will tell you not to do either, but in a recent replicated research trial on my own paddock, consisting primarily of brome and Garrison meadow foxtail grass, fertilizing with 35 pounds of nitrogen as ammonia nitrate yielded three times more on the first cutting of hay. The fertilized hay contained 17.9% NSC, while the non-fertilized hay contained 23.1% NSC--a 29% increase. The relationship between low nitrogen (in this case, from less fertilizer) and higher NSC is well documented in forage science literature.”

These figures are also higher than the typical grass hay average NSC content of 13%, notes Watts. This is an example of significant increases in the NSC content of much of the first-cutting hay in the intermountain west due to cooler than normal temperatures in the region this spring, she adds. “Which cutting has nothing to do with NSC content, although a lot of people seem to think it should. Environmental conditions and management preceding cutting are more important.

“Here's the concept: Photosynthesis is like the factory that makes raw materials, which happens as long as the sun is shining,” she describes. “In a plant, respiration is like the manufacturing portion of the plant that turns out finished goods. Even if the factory shuts down because an essential ingredient is missing, the raw materials are still coming in if the sun is shining. So sugars (raw materials) pile up in inventory. If you starve, neglect, or chill the grass so it can't grow, the sugars pile up."

She also addresses pasture mowing, noting that there is a difference between overall plant growth and elongation of the stem supporting the high-sugar seed head. The head is developed well before it rises up above the rest of the plant, it's just less accessible to the horse, she says. Owners need to mow once the seed heads pop up above the mower line.

"Then that seed head can't re-form, and the plant starts growing more leaves and tillers from the bottom of the plant.  In some regions, additional mowing may be necessary to remove secondary heads. The sugars for the seeds will now be distributed more across the whole plant, and it will be harder for horses to selectively graze only the sweetest stuff. Avoid grazing grass in the heading stage, mow it and graze the regrowth.

"I think we also need to avoid grazing stubble, as the lower you go in the stem, the higher the carbs," she adds. "In many varieties of grass, the lower part of the stem is a storage organ. The plant keeps all the goodies lower where a grazing animal can't wipe out all its resources (by nipping off the top of the plant)."

She also recommends rotating pastures. "You mow, fertilize, water, grow to 6-12 inches, put horses on, then nurture another patch while they graze that one," she says. This helps avoid horses grazing pasture down to the high-sugar stem bases.

About the Author

Christy M. West

Christy West has a BS in Equine Science from the University of Kentucky, and an MS in Agricultural Journalism from the University of Wisconsin-Madison.

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