Grazing horses on cool-season annual grasses
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One of the biggest expenses of owning a horse is feed costs and horse owners often look for ways to decrease these costs. Pastures can provide an economical source of forage for horses, and a well-managed pasture can meet or exceed the dietary requirements for many categories of horses. Therefore, maximizing pasture productivity can be a valuable tool for reducing feed costs.
In a two-year (2013-2014) study of cool-season annual grasses as forage alternatives, horse preference, yield, yield distribution, and forage nutritional values were evaluated. Based on a combination of these factors, we found that annual ryegrass appears to be a good option for horse owners looking to extend the grazing season or when in need of emergency forage during both the summer and fall seasons.
Extending the grazing season
In the upper-Midwest, cool-season perennial grasses are the foundation of productive horse pastures. However, there may be opportunities to utilize alternative forages, such as annual cool-season grasses, to extend the grazing season to earlier in the spring or later in the fall. Annuals also can be used to provide forage in emergency grazing situations when perennial forages are lost following winterkill, floods, or drought.
Spring and summer seeding
Annual grasses seeded in the spring and grazed during the summer, included spring barley, spring oat, spring wheat, winter wheat, and annual ryegrass. Grasses seeded in the summer and grazed during the fall included the same five spring-planted species plus winter barley, winter rye, and a forage-type spring oat.
Prior to grazing, all grasses were evaluated for maturity and sampled to determine yield and forage nutritive values. Adult horses grazed all grasses for 4 hours, beginning in June for summer-grazed grasses and beginning in September for fall-grazed grasses. Immediately after grazing, horse preference was determined by visually assessing the percentage of available forage eaten on a scale of 0 (no grazing activity) to 100 (100% of the existing vegetation grazed). Grasses were mowed to an even height and allowed to regrow, and grazing was repeated once grasses regrew.
Distinct grass preferences
Horses showed distinct preferences among the grasses (Figures 1a-d). In general, horses preferred annual ryegrass, spring wheat, and winter wheat, which had percent removals ranging from 35% to 94%. Horses had a lesser preference for spring oat, spring forage oat, winter barley, and winter rye, which had percent removals ranging from 7% to 32%.
Among the summer-grazed grasses, yields were typically higher for annual ryegrass and spring oat (1.7 to 2.1 tons/acre) and lower for spring wheat, spring barley, and winter wheat (1.1 to 1.8 tons/acre). Among the fall-grazed grasses, yields were typically higher for spring forage oat, annual ryegrass, and winter barley (1.2 to 2.9 tons/acre) and lower for spring wheat, spring barley, and winter rye (0.9 to 1.9 tons/acre).
Regrowth potential for future grazing
Additional consideration should also be given to regrowth potential, as a greater amount of regrowth following grazing will result in increased forage availability for future grazing events. In general, annual ryegrass and the winter species (winter wheat, winter barley and winter rye) had the greatest regrowth potential (Figures 2a-c), producing more even and consistent yields across subsequent grazing events. In contrast, spring barley, spring oat, and spring wheat produced a higher portion of their total season yield during the first grazing but had little to no regrowth available for subsequent grazing events.
Forage nutritive values differed among the annual grass species. Nutritive values were affected primarily by plant maturity, with winter species remaining more vegetative and generally having greater forage nutritive values compared to spring species. However, all grasses contained 18% or more crude protein, 58% or less neutral detergent fiber, 17% or less nonstructural carbohydrates, and 2.08 Mcal/kg or more of equine digestible energy and would meet the crude protein and digestible energy requirements of many classes of adult horse.
Read the full report
The research paper includes data charts and forage nutritive value comparison tables. (PDF 643KB)