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Tall fescue for dairy cattle

Jerry Cherney and Debbie Cherney Published on 29 August 2014
Alfalfa seeding with orchardgrass

Most cropland in the northeastern U.S. is better suited to perennial grass production than to legumes or row crop production.

Grasses also have advantages when it comes to nutrient management, with a good response to manure, which can be applied multiple times during the season. Endophyte-infected tall fescue has a deservedly poor reputation, but new tall fescue varieties have much greater potential as quality forage.

Keep in mind that there are hundreds of tall fescue varieties for sale, but most are endophyte-infected low-growing types used as turf grass. However, the number of forage tall fescue varieties on the market has increased dramatically in the last decade.

Fescue feeding trials
A number of dairy cattle feeding trials have been conducted at Cornell University using endophyte-free tall fescue silage. Tall fescue was harvested at approximately 55 percent neutral-detergent fiber (NDF).

Rations were balanced for maximum NDF. This allowed most cows to attain their potential with intakes and maximize the use of homegrown feeds with a favorable impact on farm nutrient balance.

Overall conclusions of these trials are: Tall fescue silage can produce as much milk per cow as alfalfa silage when rations are balanced, no palatability problems were observed with tall fescue, and dry matter intake increased as the portion of concentrate in diets increased, resulting in higher milk production in high-fescue diets compared to high-alfalfa diets.

Milk per acre and GRASVAL per acre

Variety trials
Several large tall fescue variety trials have been conducted over the last decade in New York state, funded by the Northern New York Agricultural Development Program. Most alfalfa variety trials in the U.S. have many entries and are generally representative of all the available varieties.

Perennial grass variety trials, on the other hand, usually have few entries, and those are often experimental selections not available for sale as varieties. The main advantage of a grass variety trial funded independent of company entry fees is that a comprehensive set of varieties can be included, representing the range of varieties currently available for sale.

The latest of these tall fescue trials was recently completed, and results are available (Northern New York - Agricultureal Development Program). Established at the W.H. Miner Agricultural Institute in Chazy, New York in 2011, 40 varieties were evaluated, including five pairs of varieties that had both an endophyte-free and a novel-endophyte version.

Most tall fescue in the U.S. is still endophyte-infected. Endophytic fungus benefits fescue plants by making them much more resistant to stresses but also makes the forage generally unacceptable for ruminants.

The novel endophyte was developed to give fescue plants heat, drought and pest tolerance but without the toxic forage effects caused by the normal endophyte.

In the current indexes to evaluate forage yield plus quality, most of the forage value is attributed to yield, not quality. Significant change in fiber digestibility (NDFd) has a very limited effect on the overall forage value. For the forage value spreadsheet Milk2006, for example, yield is responsible for more than 80 percent of the total value of the forage.

A 1 percentage unit increase in NDFd can increase milk production in high-producing cows by over 1 pound per day. Forage value indexes should reflect the importance of fiber digestibility. We created a new index, called Grasval, in an attempt to place more equal weight on forage quality and yield.

This was done by making the value of a 1-unit change in energy equal to the value of a 1-unit change in protein. Protein value of forage was calculated using the Forval program (found at Cornell University Grasval places more value on changes in fiber digestibility compared to previous indexes.

Trial results
Novel-endophyte varieties did not produce higher yields than their endophyte-free counterparts in either year of the current study.

This agreed with results from several earlier trials in New York state. While novel-endophyte tall fescue varieties are essential in areas of the mid-south U.S. with high stress levels in the summer, there is no advantage in purchasing the relatively high-priced novel-endophyte varieties in the northeastern U.S.

Endophyte-free tall fescue has survived northern New York winters over the past decade and does not appear to have any persistence problems in the Northeast.

Spring heading date of a variety had very little effect on total seasonal yield. The top tall fescue varieties have yielded up to 16.5 tons silage equivalent per acre in New York state trials, with up to a 3-ton range among entries in a given trial.

Tall fescue generally ranks highest for yield among cool-season grass species in the Northeast and the Midwest. In New York, tall fescue typically yields up to 20 percent higher than other perennial grasses. Tall fescue in general is high-yielding, but there also is a significant range in yield among varieties.

Grass composition tends to be more variable than with legumes, due to a range in nitrogen fertilizer application rates and because forage quality declines daily at a much faster rate in grasses compared to legumes.

Tall fescue is typically somewhat lower in crude protein than most other grasses, except for timothy, but is similar in fiber content and overall quality.

Early maturing varieties can be as much as 10 percentage units lower in NDF at heading compared to late-maturing varieties. A late-heading variety matures slower but declines in quality at almost the same rate per day as an early heading variety.

Both NDF and NDFd in tall fescue spring growth are controlled as much by plant age (day of year) as they are by morphological maturity. An early heading variety can be at optimal quality near heading, while a late-maturing variety needs to be harvested well before heading for optimal quality.

Using the Grasval index, the ranking of some varieties for yield plus quality does change compared to the ranking of varieties for yield only. Increased fiber digestibility adds significantly to the overall forage value of Grasval.

The strong negative relationship between NDF at heading and NDFd at heading, however, implies that there have not been significant advances in breeding for higher NDFd in tall fescue. The highest Grasval per acre should be the best combination of yield and quality.

Ranking of varieties for yield or quality tends to be site-specific. For example, a tall fescue variety trial conducted in New York state may not contain much useful information for a Wisconsin farmer.

Implications for mixed stands
Because the vast majority of alfalfa seedings in our area are made with a companion perennial grass, there is considerable interest in the alfalfa with tall fescue combination. In a mixed stand, most producers are looking for a relatively high proportion of alfalfa, with the highest possible NDFd at harvest.

High grass yield may not be desirable, as this likely indicates a more competitive grass. Harvest date is usually based on alfalfa maturity, not grass maturity. Therefore, if choosing a tall fescue variety to seed with alfalfa, simply select the variety in a trial with the highest NDFd at spring harvest. Most likely, this means selecting a later-maturing tall fescue variety for seeding with alfalfa.

We have not seen any persistence problems with endophyte-free tall fescue in the Northeast, so the addition of a novel-endophyte may be of limited value here. There is a significant range in both yield and quality among varieties.

Tall fescue, which is relatively easy to establish, is suited to either hay or silage production or pasture systems. Intensive management is required for high silage yields in the 50 to 55 percent NDF range.

For more information on this subject, see the series of information sheets on grass management for dairy cattle at Cornell University forages.orgFG

Debbie Cherney is an associate professor of animal science at Cornell University.

References omitted due to space but are available upon request. Click here to email an editor.

Alfalfa seedings in the Northeast are often seeded with a companion perennial grass, such as orchardgrass. There is a growing interest in an alfalfa and tall fescue combination. Consider choosing a tall fescuevariety trial with high NDFd at spring harvest. Photo by FG staff.

Jerry Cherney
  • Jerry Cherney
  • E.V. Baker Professor of Agriculture
  • Cornell University