Cooperative Extension Service
The University of Georgia College of Agricultural and Environmental Sciences
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John Andrae, Extension Agronomist -- Forage Crops

Available novel endophyte-infected tall fescue products
Will novel endophyte-infected tall fescue persist?
How will animals perform on novel endophyte-infected tall fescue?
Establishing novel endophyte-infected tall fescue
Summary

Tall fescue is a cool season grass that fills a critical forage production gap in middle Georgia and is the predominant forage crop in north Georgia. This species is called the most important cultivated pasture grass in the USA and its popularity is related to establishment ease, drought tolerance, excellent grazing persistence and long grazing season.

Many of these desirable attributes are due to the presence of a fungus (Neotyphodium coenophialum) that lives inside the plant (endophyte). This fungus is transmitted in seed and not through pollen. Unfortunately, this endophyte produces toxic alkaloids that greatly decrease animal gains and reproductive performance. This decreased animal performance was conservatively estimated in 1993 to cost the United States beef industry over $600 million annually. Removing the endophyte alleviates animal symptoms and furnishes good gains but causes plant stand losses from drought and heavy grazing. Recently, endophyte strains that do not produce toxic ergot alkaloids have been identified and inserted into tall fescue varieties. Replacement of toxic tall fescue stands with these novel endophyte-infected varieties will benefit producers if new stands (1) persist as well as toxic tall fescue under grazing and (2) provide animal performance at levels comparable to endophyte-free tall fescue. This bulletin outlines plant persistence and animal performance characteristics of novel endophyte-infected tall fescue and documents recommended pasture renovation practices.

Available novel endophyte-infected tall fescue products

Currently, only one product containing a novel endophyte is available in Georgia. MaxQ^TM tall fescue was a joint venture between Dr. Joe Bouton at the University of Georgia and Dr. Gary Latch at Ag-Research Limited of New Zealand. Novel endophytes from New Zealand were inserted into tall fescue cultivars developed in Georgia to produce a non-toxic endophyte-infected forage. These endophyte/tall fescue variety pairs have been tested extensively in Georgia on both experiment stations and producer farms. Currently the MaxQ^TM endophyte is available in Georgia 5 and Jesup tall fescue varieties. Both of these varieties were developed in Georgia and perform well in conjunction with this endophyte.

Another novel infected tall fescue developed in Arkansas and Missouri is scheduled for release in fall, 2003. This product (named ArkPlus^TM) contains a novel endophyte inserted into the HiMag tall fescue variety. It has not been tested in Georgia; plant it with caution until plant performance can be determined for the southeastern United States. Plant persistence testing in Georgia is currently underway.

Yield data does not differ greatly among endophyte types, and yield measurements generally mean little to forage producers. The most critical measure of plant performance is whether or not plants persist for reliable forage production under severe grazing and drought conditions.

Figure 1. Building a novel endophyte-infected tall fescue. Orange ovals represent tall fescue plant cells, and blue and red lines represent toxic and novel endophytes, respectively. Cartoon courtesy of Dr. C. Roberts, University of Missouri.

Will novel endophyte-infected tall fescue persist?

Attention in past years has focused on preventing fescue toxicosis by removing the toxin-producing fungus and establishing endophyte-free stands. Gains and reproductive performance of animals grazing endophyte-free tall fescue are higher than toxic tall fescue; however, these pastures are intolerant of drought and heavy grazing and frequently fail. Because of this potential for stand losses, many producers elect to plant more "dependable" toxic tall fescue and tolerate economic losses associated with the toxins. Persistence of novel endophyte-infected tall fescue must be substantially better than that of endophyte-free tall fescue to justify higher seed costs and destruction of existing toxic tall fescue stands.

To test persistence under severe grazing conditions, MaxQ^TM, endophyte-free and toxic tall fescue were planted into a bermudagrass sod near Eatonton, Georgia (Figure 2). These plots were established on droughty soils and grazed closely during two summers to accel-erate stand decline and evaluate endophyte effects on plant persistence. All entries declined because of the heavy grazing pressure and bermudagrass competition; however, MaxQ^TM infected varieties persisted as well as wild-type toxic endophyte infected counterparts and were more persistent than endophyte-free checks. This study was continued over a four-year period with MaxQ^TM maintaining stands equal to toxic tall fescue. Similar results have been obtained in grazing trials near Calhoun, Georgia.

Figure 2. Stand persistence of Jesup MaxQTM tall fescue after two years of close grazing in bermudagrass sod. Data collected in Eatonton, Georgia. (Bouton et al., 2000)

Pure stands of MaxQ^TM have also been evaluated for grazing persistence at the Upper Coastal Plains Experiment Station near Winfield, Alabama. After one year of grazing, stands of MaxQ^TM were about 80 percent and equal to stands of toxic tall fescue. Endophyte-free tall fescue stands were lower than either toxic or MaxQ^TM tall fescue and averaged only 30 percent.

Persistence of MaxQ^TM endophyte-infected tall fescue approaches that of toxic tall fescue under harsh grazing conditions. It is reasonable to expect that MaxQ^TM in pure stands under moderate grazing con-ditions will survive as well as toxic tall fescue and will persist much better than endophyte-free tall fescue. In beef cattle and sheep grazing research trials conducted at Eatonton, MaxQ^TM established in 1997 and 1998 have maintained strong stands through four years of summer droughts. Plant persistence data of ArkPlus^TM is currently inadequate to predict its performance in Georgia. Research is currently underway to evaluate its potential.

How will animals perform on novel endophyte-infected tall fescue?

Cow-Calf Performance

Cow-calf performance data on novel tall fescue is limited, but weaning weight responses are promising. In the first two years of a study conducted in northwest Georgia, cows grazing novel endophyte infected tall fescue tended to have higher body condition scores and weights than cows that grazed toxic tall fescue. Steer and heifer calves grazing novel tall fescue also had approximately 50 and 60 pounds greater weaning weights, respectively, than contemporaries grazing toxic tall fescue (Figure 3). Results from the third year of this study indicate similar improvements in weaning weight for calves grazing MaxQ^TM. Cattle numbers were too small to determine if reproductive characteristics were positively affected; however, performance of cow-calf pairs on MaxQ^TM tall fescue appears to be excellent.

Figure 3. Calf weaning weights of cattle grazing toxic or MaxQTM tall fescue stands. Values are averages of two years' data collected near Calhoun, Georgia. (Bouton et al., 2000, and Watson et al., 2001)

Stocker Performance

Stocker cattle performance has been examined for several years at sites throughout Georgia and the Southeast (Table 1). These studies indicate that ArkPlus^TM and MaxQ^TM pastures support cattle gains superior to toxic tall fescue and equivalent to endophyte-free pastures. Many of these studies also indicate that hair coat scores and rectal temperatures improve in both endophyte-free and novel endophyte-infected pastures. Preliminary data from Alabama, Louisiana and Tennessee agree with studies listed in the table. Animal behavioral data collected near Eatonton, Georgia, indicate that cattle stocked on MaxQ^TM pastures spent more time grazing and less time idling than cattle stocked on toxic tall fescue (Figure 4).

Figure 4. Cattle grazing toxic tall fescue (foreground) spent less time grazing, while cattle grazing MaxQTM (in background) and endophyte-free tall fescue had higher intakes and performance. (Photo taken in spring 2001 near Eatonton, Georgia; Parish 2001).

Subsequent Feedlot Performance

Following three of the Georgia stocker grazing studies, cattle grazing MaxQ^TM, endophyte-free and toxic endophyte tall fescue were finished on high-concentrate diets. Subsequent feedlot performance of cattle that grazed MaxQ^TM, endophyte-free and toxic endophyte tall fescue indicate no difference in animal performance, feed efficiency or most carcass quality measurements among endophyte groups. However, because of improved stocker performance the cattle that grazed endophyte-free and MaxQ^TM paddocks entered the feedlot heavier and had heavier carcass weights after an equal time on feed (Figure 5). This, in combination with numerically higher quality grades, resulted in a $108 per head advantage for MaxQ^TM versus toxic endophyte pastured cattle. While there appeared to be no feedlot performance depression from fescue toxicosis, heavier weight gains on MaxQ^TM pastures will either (1) increase finished weights or (2) decrease time-on-feed which ultimately translates into more profitable beef production.

Figure 5. Subsequent feedlot performance of cattle that grazed toxic, endophyte-free and novel tall fescue. Cattle originally grazed pastures in Eatonton and Calhoun, Georgia, and were finished in Stillwater, Oklahoma. (Duckett et al., 2001)

Equine Performance

Mares in late gestation are particularly sensitive to alkaloids produced by toxic endophytes. To date, there is limited research studying the effects of novel endophyte tall fescue on mare performance in late gestation and early lactation. In a study conducted in Mississippi, five mares grazed either MaxQ^TM, endophyte-free or toxic tall fescue pastures. Of the mares that grazed toxic endophyte tall fescue, 80 percent did not produce milk, 40 percent had compromised deliveries, 60 percent had retained placentas, and one mare (20%) aborted. No problems were noted for mares grazing endophyte-free or MaxQ^TM tall fescue. Mares grazing toxic endophyte-infected pastures also had a longer gestation period and thicker placental membranes than mares that grazed MaxQ^TM or endophyte-free tall fescue pastures. These findings led the researchers to suggest that the risk to pregnant mares grazing properly established MaxQ^TM tall fescue with no toxic contaminants appears to be nonexistent.

Establishing novel endophyte-infected tall fescue

Planting novel endophyte tall fescue into a 'clean' field that does not contain living toxic tall fescue plants or viable seed is critical to (1) eliminate potential toxicity in pregnant mares (2) maximize beef cattle performance and (3) minimize potential for toxic plants and seedlings to reestablish in the pasture.

Establishing in cropland. Planting into existing cropland is relatively simple. Soil test the field, apply recommended nutrients, and plant 20 pounds of seed per acre into a firm seedbed at ¼-inch depth from late September to early November. When no-till sod-seeding into dormant bermudagrass, increase seeding rate to 25 pounds per acre. Planting novel endophyte tall fescue into fields that contain toxic tall fescue is more difficult and requires planning.

Establishing in existing stands of toxic tall fescue. To ensure that viable volunteer tall fescue seed is not present in the field, plants cannot be allowed to produce seed during spring of the planned establishment year. Prevent seed production by closely grazing or mowing tall fescue when plants are in the boot stage. Soil test in the spring and apply recommended lime. This allows time for lime to react and increase soil pH before fall planting. Successfully removing toxic tall fescue from existing pastures has been most successful when a spray-smother-spray technique is followed.

1. Spray. Apply Roundup^TM or Gramoxone^TM in the spring to kill existing forage. If bermudagrass or dallisgrass is present in the pasture, research shows that Roundup^TM is the only effective herbicide.
2. Smother. Drill a summer annual grass into the sod in late spring to supply some summer grazing. Graze the forage in the summer or harvest for hay. If forage is grazed, do not move animals onto the field from other toxic tall fescue pastures without a 3 day clean-out period on a non-toxic forage.
3. Spray. Remove remaining forage in September by grazing or mowing and spray with Roundup^TM to kill any remaining tall fescue and bermudagrass. Apply recommended fertilizer and no-till novel endophyte tall fescue at 25 pounds of seed per acre. Clean-tilled seedbeds can be planted at 20 pounds per acre.

Avoid grazing seedling novel endophyte tall fescue stands until plants are at least 8" tall. Graze lightly during fall and spring of the establishment year to allow seedlings to develop adequate root carbohydrates to survive the summer. If possible (1) avoid grazing the stand in the fall and harvest forage for hay and (2) defer summer grazing to help establish a deep root system.

Summary

Tall fescue varieties containing the novel endophytes (both ArkPlus^TM and MaxQ^TM) produce animal gains similar to endophyte-free tall fescue. While persistence of ArkPlus^TM in Georgia is currently unknown, the plant persistence of MaxQ^TM approaches or equals toxic endophyte infected tall fescue. This makes MaxQ^TM tall fescue an attractive alternative to either toxic or endophyte-free tall fescue for pasture establishment and renovation.

Circular 861/February, 2003

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