Cool-season perennial grasses for horse pastures

Perennial ryegrass is a cool-season grass known for its high seedling vigor, yield and nutritive value. Perennial ryegrass thrives in regions of the U.S. with milder winters, but lacks the winter hardiness needed to persist in the Upper Midwest.

The perennial ryegrass breeding program at the University of Minnesota identified a few experimental perennial ryegrasses that are more winter hardy.

We tested perennial ryegrasses for yield, persistence, nutritive value and preference under livestock grazing.

How the research was completed?

The following grasses were established in St. Paul and Grand Rapids, Minn. pastures in the late summer:

• Meadow fescue (‘HDR’)
• Tall fescue (‘STF-43’)
• Orchardgrass (‘Intensiv’)
• Perennial ryegrass (‘Remington’)
• Two experimental winter-hardy, perennial ryegrasses

Grazing began the following spring with horses in St. Paul and beef cow-calf pairs in Grand Rapids. The animals grazed the grasses in a monthly rotation during the grazing season for two years.

Before grazing, we took yield and quality samples of the grasses. After grazing, we recorded the percent of grasses removed to determine preference. In the spring after two years of grazing, we also measured stand persistence of the seeded grasses.

Yield

• In the first year, the grasses had similar yields, which ranged from 4.2 to 5.1 tons per acre.
• In the second year, perennial ryegrass yielded 1.9 to 2.2 tons per acre while the other grasses yielded over 3.1 tons per acre.
• ‘Remington’ perennial ryegrass and the two experimental perennial ryegrasses had similar yields.

Stand persistence

After two years of grazing, all the grasses in St. Paul presented over 65 percent ground cover, which is used to measure stand persistence. In Grand Rapids, all of the perennial ryegrasses had less than 40 percent ground cover, which was lower than the other grasses. ‘Remington’ and the two experimental perennial ryegrasses had similar ground cover.

During the winter following the second year of grazing, much of Minnesota had over a week of very cold temperatures, where the overnight lows ranged from -15 to -44°F. These temperatures likely caused poor persistence in the perennial ryegrasses in Grand Rapids even though the fields had snow cover.

Nutritive value

Perennial ryegrasses were among the highest for the following

• Crude protein: greater than 19 percent
• Equine digestible energy: greater than 1.0 Mcal per pound
• Bovine metabolizable energy: greater than 1.1 Mcal per pound
• Neutral detergent fiber digestibility at 48 hours: greater than 85 percent

Perennial ryegrasses were moderate in nonstructural carbohydrates at 12 to 16 percent and among the lowest for neutral detergent fiber at less than 54 percent.

Although we did not see consistent trends in nutritive value among the other grasses orchardgrass tended to be higher in neutral detergent fiber at greater than 59 percent and lower in the following

• Crude protein: 18 percent
• Nonstructural carbohydrates: 10 percent
• Energy content
• Neutral detergent fiber digestibility at 48 hours: greater than 82 percent

Preference

• The horses and cattle highly preferred all of the perennial ryegrasses.
• The horses removed over 74 percent of the perennial ryegrasses, while the cattle removed over 70 percent.
• The horses and cattle tended to prefer the orchardgrass less.

Livestock tended to prefer grasses with higher crude protein and energy content over grasses with a higher neutral detergent fiber. More preferred grasses tend to result in better uniform grazing and maximize forage use by livestock.

Additional resources

D. N. Catalano, C. C. Sheaffer, N. P. Wiering, A. M. Grev, N. J. Ehlke, E. Mousel, K. L. Martinson. 2020. Yield, persistence, forage nutritive value, and preference of perennial ryegrass under grazing. Agronomy Journal.

Acknowledgements

The research was funded by the Minnesota Department of Agriculture.

Researchers

Krishona Martinson, Extension equine specialist; Eric Mousel, Extension livestock educator; Craig Sheaffer, professor of agronomy and plant genetics, and Nancy Ehlke, professor of agronomy and plant genetics, College of Food, Agricultural and Natural Resource Sciences; Nick Wiering, graduate student, College of Food, Agriculture and Natural Resource Sciences; Devan Catalano, Woody’s Horse Nutrition; and Amanda Grev, University of Maryland

How the research was completed

We grazed four adult horses on the following species in pure stands:

• Creeping foxtail
• Kentucky bluegrass
• Meadow bromegrass
• Meadow fescue
• Orchardgrass
• Quackgrass
• Reed canarygrass
• Perennial ryegrass
• Smooth bromegrass
• Tall fescue
• Timothy

The horses grazed the research area for three consecutive days each month from May to October in 2010 and May to September in 2011. 

• We evaluated grass maturity and persistence, measured yield and quality and then grazed the horses when most tall growing grasses reached eight inches. 
• We visually assessed preference and persistence after each grazing event. 
• Following grazing, we removed manure, mowed remaining forage to three inches and allowed it to re-grow. 
• We fertilized grasses with nitrogen in early April and mid-June and applied broadleaf herbicide once a year in spring. 

Trial results

• Under horse grazing, orchardgrass, meadow fescue, tall fescue and Kentucky bluegrass were the most persistent (best ground cover) and highest yielding grasses.
• Smooth bromegrass, creeping foxtail and timothy were the least persistent and lowest yielding grasses. 
• Kentucky bluegrass, timothy and meadow fescue were the most preferred grasses.
• Meadow bromegrass, creeping foxtail, reed canarygrass and orchardgrass were less preferred. 

Yield

• Orchardgrass, tall fescue, meadow fescue and Kentucky bluegrass were the highest yielding grasses and averaged 4.0 to 5.4 tons per acre each year.
  • These same four grasses were also the most persistent under horse grazing.
• Creeping foxtail, smooth bromegrass and timothy were the lowest yielding grasses.

In this study, the highest yields for most grasses occurred during summer. Of the total forage yield, 40 percent occurred in the summer for 2010 and 83 percent for 2011.

In pasture systems, you can maintain immature plants by frequently grazing horses and routinely mowing. This practice allows for similar plant growth rates throughout the season.

Forage nutritive value

Overall, creeping foxtail was the lowest quality cool-season grass. Levels of non-structural carbohydrate (NSC) were similar among the grasses in spring and fall.

Horses are selective grazers, but we know little about what drives horse preference in a pasture system. In this study we found that in 2010:

• NSC level positively correlated to horse preference.
• There was a trend for NDFD level to be positively correlated with preference.
• There was a trend for NDF level to be negatively correlated to horse preference.
• Crude protein and maturity were not correlated to horse preference.

In 2011, we found that no forage nutritive values or maturities correlated to horse preference. It's widely accepted that horses (and other livestock) prefer forages that are lower in fiber (NDF) and higher in carbohydrates (NSC). The lack of consistent correlation between forage nutritive value and horse preferences in 2011 highlights how complicated horse preference is.

Horse preference (forage removal)

• Plant forage with similar preference ratings in horse pastures to maximize forage use.
• Mixtures that result in uniform grazing will help maximize forage use and reduce pasture maintenance and related expenses.
• See the grass comparison table for specific preference values among species.

Forage persistence (ground cover)

Reed canarygrass, smooth bromegrass and timothy won't regrow well if cut or grazed during stem lengthening. During this phase, regrowth becomes interrupted.

More persistent species such as orchardgrass can continue to regrow during stem lengthening.

In general, we recommend starting grazing when tall, cool-season grass pastures are at six to eight inches in height. This recommendation will likely result in reed canarygrass, smooth bromegrass and timothy being at the stem lengthening stage at the start of each rotational grazing period.

As a result, these plants may be particularly prone to poor persistence. Avoid grazing horses during the stem lengthening stage or avoid using these grasses in pastures.

Acknowledgements

This project was funded by the University of Minnesota Agricultural Experiment Station, the University of Minnesota Grant‐In‐Aid Program, and Midwest Forage Association.

Researchers

Elizabeth Allen, College of Food, Agricultural and Natural Resource Sciences; Craig Sheaffer, professor of agronomy and plant genetics, College of Food, Agricultural and Natural Resource Sciences; Krishona Martinson, Extension equine specialist