J. Anim. Sci. 2004. 82:E75-E82
© 2004 American Society of Animal Science
Novel endophyte-infected tall fescue for growing beef cattle1
S. A. Gunter2 and
P. A. Beck
Southwest Research and Extension Center, Department of Animal Science, University of Arkansas, Hope 71801-9729
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Abstract
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Tall fescue (Festuca arundinacea, Shreb.) is the predominant cool-season, perennial grass in the eastern half of the United States, and the majority is infected with the endemic endophyte (E+) Neotyphodium coenophialum, resulting in millions of dollars in revenues lost to the beef industry. Endophyte-free (E–) tall fescue was initially tapped as a "silver bullet" for the solution to fescue toxicosis, but drought intolerance and overgrazing have often resulted in nearly complete stand losses in 3 to 4 yr. Recently, the discovery of new endophytes that do not produce ergot alkaloids has resulted in the development of novel-endophyte-infected (NE+), stress-tolerant tall fescue plants. These NE+ tall fescue plants combine the plant persistence advantages of E+ (infected) tall fescue with the animal performance advantages of an E– tall fescue. Controlled studies from several locations in the southern United States have shown that the three commercially available cultivars of NE+ tall fescue persist as well as E+ tall fescues. Stocker cattle performance trials from five states have shown that the ADG in cattle grazing NE+ tall fescue was 47% greater than in cattle grazing E+ tall fescue and that cattle show no signs of fescue toxicosis. Economic evaluations of establishment cost and improved animal performance indicate that a stand of NE+ tall fescue would require 7 yr to pay off and begin to return profit to the enterprise if calves grazing E+ pasture are not discounted in price for fescue toxicosis at marketing. Average discounts at marketing for cattle showing signs of fescue toxicosis are $7.49/45.4 kg of BW. Assuming E+ cattle are discounted at sale and the quality of cattle is not decreased by the use of NE+ tall fescue, a stand of NE+ tall fescue would require 3 yr to pay the expense of establishment and begin to return profit to the enterprise.
Key Words: Festuca arundinacea • Acremonium coenophialum • Cattle • Endophytes
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Introduction
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Tall fescue (Festuca arundinacea, Shreb.) is a predominant cool-season, perennial grass in the United States, covering over 14 million ha (Thompson et al., 2001). This tall fescue is infected with an endemic endophyte (E+), Neotyphodium coenophialum (Glenn et al., 1996; formerly called Acremonium), that lives in the intercellular spaces. Fescue toxicosis resulting from E+ affects over 8.5 million cattle (Ball et al., 1996), and the impact to the beef industry has been estimated to exceed $609 million annually (Hoveland, 1993). The endophyte infection of tall fescue provides the plant with agronomic attributes that make it attractive as a forage, including an ability to withstand drought, produce forage in winter, and withstand intense defoliation.
Identifying the causative agent allowed researchers to develop endophyte-free (E–) tall fescue, which can provide excellent animal performance. Also, because endophytes are passed from generation to generation via the seed (Thompson et al., 2001), an established pasture of E– tall fescue should have persisted indefinitely. Unfortunately, these E– tall fescues are less tolerant of drought and grazing than are the E+ grasses, often resulting in the nearly complete loss of the stand in 3 to 4 yr. The inability of E– fescue to persist resulted in its being an uneconomical and nonviable alternative to E+ fescue.
The discoveries of novel endophytes that do not produce or produce very small amounts of ergot alkaloids have augmented the value of tall fescue. Because these new endophytes produce nearly no ergot alkaloids, which have been suggested as being the major toxins produced in E+ fescue (Bacon et al., 1977), plants containing a novel endophyte should combine the persistence advantages of E+ tall fescue with the animal performance advantages of an E– tall fescue. The development and use of stress-tolerant tall fescue with a novel endophyte have been suggested as the next major advance for livestock production (Parish, 2001).
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Novel Endophytes
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Researchers from the University of Georgia concluded that the selection of endophytes that produced low levels of ergopeptine alkaloids, especially ergovaline, in tall fescue plants resulted in little or no loss in plant fitness (Hill et al., 1991). Hence, selecting endophytes that have nil ergovaline production in tall fescue has been suggested to possibly improve animal performance compared to E+ tall fescue (Agee and Hill, 1994). Selective elimination of livestock toxins has produced several commercially available tall fescues to date. The first available NE+ tall fescues were two varieties (‘Jesup’; Bouton et al., 1997 and ‘Georgia-5’; Bouton et al., 1993) containing the endophyte AR542 from Pennington Seed, Inc. (MaxQ; Madison, GA). The endophyte AR542 was discovered and isolated by Ag Research in New Zealand. Also, the University of Arkansas has been actively pursuing the development of a tall fescue containing a NE+. This program has developed a variety released in 2002 that is a combination of HiMag (Sleper et al., 2002) tall fescue and the Strain 4 NE+; seed is now commercially available as ArkPlus tall fescue through FFR Cooperative (Lafayette, IN).
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Plant Persistence
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The ability of a perennial grass to persist is its most important trait; forage DM production, nutrient quality, and season of production are all traits of secondary importance. Information regarding the persistence of Jesup AR542, Georgia 5 AR542, and HiMag Strain 4 is still extremely limited by the fact that experiments have been started in few locations and most published experiments have been in progress for only 2 or 3 yr. However, there has been some research regarding the ability of these NE+ new grasses to persist. Hoveland (1993) stated that selecting fungal endophytes that minimize the harmful properties and maintain the benefits to the host plant is the "final solution" to the fescue toxicosis problem. Jesup AR542 and Georgia 5 AR542 are currently being tested in Georgia in bermudagrass sod compared to E+ and E– tall fescues. To evaluate their persistence under harsh conditions (Bouton et al., 2002), plots have been grazed two summers by sheep in central (Eatonton) and southern (Tifton) Georgia. After one summer of grazing, Jesup AR542 and Georgia 5 AR542 varieties persisted as well as the E+ counterparts and were more persistent than their E– counterparts (Table 1
). After the second year of grazing, Jesup AR542 was still as persistent as the E+; however, Georgia 5 AR542 was intermediate between the E+ and the E– Georgia 5 fescues (Bouton et al., 2002).
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Table 1. Persistence of Jesup and Georgia 5 tall fescues infected with AR542 compared to counterparts infected with endemic endophyte or endophyte-free fescue at two locations in Georgia (Bouton et al., 2002)
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Ongoing research at Mississippi State University is comparing the persistence of the tall fescues Jesup E–, Jesup E+, Jesup AR542, Georgia 5 E–, Georgia 5 E+, Georgia AR542, and Kentucky 31 E+ (Lang et al., 2001). After planting in the fall of 1999, all stands started out with 100% ground cover. By October 2000, these researchers reported that the stands of Jesup AR542 and Georgia 5 AR542 ranged from 64 to 82% ground cover compared to 38 to 42% for Jesup E– and Georgia 5 E–, and 64% for Kentucky 31 E+. Researchers from northeast Alabama compared the persistence of Jesup E+, Jesup E–, and Jesup AR542 under grazing pressure from cattle stocked at 836 kg of BW/ha (Bransby et al., 2002). In the fall after planting in 1998, stands had more than a 90% ground cover with fescue across all varieties. After 2 yr, stands had 80, 30, and 82% ground cover with Jesup E+, Jesup E–, and Jesup AR542, respectively.
An ongoing trial at a Texas A&M University Agricultural Research and Extension Center in northeast Texas (Overton) is examining 12 varieties of tall fescue for persistence under grazing pressure by beef cows (M. Rouquette and L. Redmon, unpublished data). The tall fescues were planted in November of 1999 and the varieties of interest are listed in Table 2. Over the 2 yr since the tall fescue varieties have been planted, the percentage of ground cover for the varieties infected with E+ or AR542 has remained relatively constant; however, the E– varieties have decreased by as much as 52% relative to the original stand. These preliminary results indicate that tall fescues infected with AR542 show persistence equal to the E+ varieties.
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Table 2. Persistence of Jesup and Georgia 5 tall fescues infected with AR542 compared to counterparts infected with endemic endophyte or endophyte-free fescue in Texas (M. Rouquette and L. Redmon, unpublished data)
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Novel-endophyte research from the University of Arkansas has examined four endophytes hosted in HiMag tall fescue in a persistence trial comparing them to HiMag E– and Kentucky 31 E+. The stands were established by no-till drilling the tall fescues into a bermudagrass sod after spraying with 842 g of glyphosate/ha. After 3 yr of heavy grazing, the Kentucky 31 E+ and HiMag tall fescues containing the Strains 4, 7, 9, and 11 had a stand survival of 30%, where the HiMag E– decreased to 16% stand (West et al., 2001).
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Animal Performance
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Several animal performance trials have been conducted with ruminants grazing NE+ tall fescues compared to E– and E+ tall fescues. An initial grazing trial with lambs compared Jesup E+, Jesup E–, Georgia 5 AR542, and Jesup AR542 (Bouton et al., 2002). These researchers reported that lambs grazing the Jesup E+ showed signs of heat stress, increased rectal temperatures, and decreased serum prolactin concentrations relative to lambs grazing the Jesup E–; however, the lambs grazing Jesup AR542 and Georgia AR542 displayed no signs of fescue toxicosis because rectal temperatures and serum prolactin concentrations did not differ from lambs grazing Jesup E–. Average daily gain was also less for lambs grazing Jesup E+ than for lambs grazing Jesup E–, Jesup AR542, and Georgia AR542 (Bouton et al., 2002).
Another research trial (Parish, 2001) conducted in central Georgia (Eatonton) compared gains of beef steers grazing four tall fescue varieties: Jesup E+, Jesup E–, Jesup AR542, and Georgia 5 AR542 in the spring and fall (Table 3). Cattle were stocked on pastures by a put-and-take method to maintain similar forage availability among pastures. Parish (2001) reported that forage variety interacted with season. Average daily gain was less in the spring relative to the fall for steers grazing Jesup E+. This difference is likely the result of higher ergot alkaloid concentration in the spring relative to the fall (Rottinghaus et al., 1991) and the presence of seed in which ergot alkaloids concentrate (Ball et al., 1996). Steer ADG was greater for Jesup E–, Jesup AR542, and Georgia 5 AR542 than for Jesup E+ in both seasons. These researchers also reported that steers grazing Jesup AR542 had serum prolactin concentrations similar to those of steers grazing Jesup E–, suggesting that AR542 was not producing the toxins responsible for fescue toxicosis. During the fall and spring grazing seasons, tall fescues infected with AR542 produced 46 and 135% more gain per hectare than Jesup E+, respectively.
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Table 3. Performance of stocker cattle grazing Jesup tall fescues infected with AR542 compared to counterpart grazing tall fescue pasture infected with endemic endophyte or endophyte-free fescue
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A study was conducted in northeast Alabama (Crossville) with stocker cattle (average BW = 204 kg) grazing Jesup E+, Jesup E–, and Jesup AR542 from December to July (224 d) stocked at 3.7 steers/ha the entire season (Table 3
; Bransby et al., 2002). The steers grazing the Jesup AR542 pastures gained BW 23% faster than steers grazing Jesup E+, and ADG for Jesup E– was not different from Jesup AR542.
A study conducted in southwest Tennessee (Grand Junction) compared the effects of three tall fescue varieties (Waller at al., 2002) on the performance of stocker cattle (average BW = 299 kg) grazing Kentucky 31 E+, Kentucky 31 E–, and Kentucky 31 AR542 in the winter and the fall with set stocking (Table 3). In the winter, the steers grazing the Kentucky 31 AR542 pastures gained BW at the same rate as the steers grazing Kentucky 31 E+, but the ADG of steers grazing Kentucky 31 E– was approximately 68% faster than that of the steers grazing Kentucky 31 AR542 or Kentucky 31 E+. Gain per hectare was 64% greater for Kentucky 31 E– than for Kentucky 31 AR524 and Kentucky 31 E+. During the spring, the steers grazing the Kentucky 31 AR542 and Kentucky 31 E– pastures gained BW 53% faster than the steers grazing Kentucky 31 E+. Gain per hectare was 54% greater for Kentucky 31 E– and Kentucky 31 AR524 than Kentucky 31 E+. These results are similar to those reported by Bondurant et al. (2000), who evaluated the performance of stocker cattle grazing E+, E–, and AR542-infected Kentucky 31 in northern Georgia. Waller et al. (2002) also reported that serum harvested from the cattle grazing the Kentucky 31 AR542 showed no decrease in prolactin concentration compared to cattle grazing Kentucky 31 E–, whereas cattle grazing Kentucky 31 E+ had decreased prolactin concentrations.
In northeast Louisiana (Winnsboro), a study was conducted with grazing stocker cattle (112 d) evaluating four varieties of tall fescue, including the following: Georgia 5 E+, Georgia 5 E–, Georgia 5 AR542, and Jesup AR542 from January to April (Table 3; W. Alison, unpublished data). The steers grazing the Georgia 5 E–, Georgia 5 AR542, and Jesup AR542 pastures gained BW 35% faster than steers grazing Georgia 5 E+, and the ADG of steers grazing Georgia 5 E–, Georgia 5 AR542, and Jesup AR542 were similar among varieties. Gain per hectare was greater for Georgia 5 AR524 and Jesup AR524 than for Georgia 5 E– and Georgia 5 E+.
Nihsen et al. (2002) reported that stocker cattle that were grazing stockpiled Kentucky 31 E+ tall fescue in the winter and spring gained 0.33 kg daily, whereas steers grazing HiMag E– and HiMag infected with endophyte Strains 4 or 9 gained 0.61, 0.60, and 0.54 kg daily, respectively (Table 3). Steers grazing the E+ Kentucky 31 had higher respiration rates, rectal temperatures, and rougher hair coats compared to steers grazing HiMag infected with Strains 4 or 9 and E– HiMag. Plasma analysis indicated prolactin, alkaline phosphatase, cholesterol, lactate dehydrogenase, and triglyceride concentrations were decreased and creatine was increased in steers grazing Kentucky 31 E+ compared to steers grazing HiMag infected with Strains 4 or 9 and E– HiMag.
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Establishment and Economic Return
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Successfully establishing a new pasture of NE+ tall fescue on a site where E+ currently planted is of major concern to producers, researchers, and extension personnel. It has long been known that E+ tall fescue contamination of a pasture decreases ADG (Stuedemann and Hoveland, 1988) and would result in a decrease in the return on investment. The University of Arkansas Cooperative Extension Service has conducted research in this area at the Livestock and Forestry Branch Station in Batesville for establishing E– tall fescue on sites currently growing E+ tall fescue (Boyd, 1993). This procedure for establishing E– tall fescue without E+ tall fescue contamination should be applicable for use with NE+ tall fescues. The steps for this procedure include the following: 1) spray E+ tall fescue before heading in the early spring using 842 g of glyphosate/ha; 2) no-till plant pearl millet or sorghum–sudangrass for hay production during the summer as described by Phillips (1990); 3) after final cutting of hay, spray the regrowth with 842 g of glyphosate/ha; 4) no-till drill 22.4 kg/ha of Jesup AR542 into pearl millet stubble; 5) apply 336 kg/ha of blended fertilizer (17-17-17) to pastures after the fall planting; and 6) apply 167 kg/ha of ammonium nitrate to the sward in the following spring. Three sources for failure of this approach to eradicate tall fescue have been identified and are as follows: 1) applying herbicides during conditions of environmental stress, 2) poor application techniques, and 3) improper management of E– tall fescue. The summer annual crop is an important step in the process and should not be deleted. The summer annual crop serves to smother any emerging tall fescue plants (Boyd, 1993). Studies at Batesville have shown a 50% reinfection rate 1 yr after applying paraquat twice, burning the stubble, and no-till drilling the site with E– tall fescue during the same fall (Boyd, 1993). Previous research has demonstrated that for each 10% increase in E+ infection of tall fescue pasture there is approximately a 0.05-kg decrease in ADG over the entire grazing season (Stuedemann and Hoveland, 1988). Smother crops that may prove more profitable are currently being researched in Mississippi (Triplett et al., 2001). These researchers are examining the use of glyphosate-resistant corn and soybeans as a smother crops for use in the establishment of NE+ tall fescue. The benefits to using these crops include the ease of marketing, the use of multiple applications of glyphosate during the growing season to kill emerging tall fescue plants, and the greater potential for profits.
A partial budgeting analysis was constructed to compare the costs associated with the conversion of an established E+ tall fescue pasture to a pasture of Jesup AR542 pasture. The reason this production scenario was selected for economic analysis is because it would be the most difficult to accomplish and probably the most expensive. The pasture in this scenario would be reseeded using a no-till method previously described by Boyd (1993). Tall fescue pastures infected with novel endophyte would be cut for hay in May and July during the first year after establishment and any grazing done to promote tillering will not be counted in the first year’s income because it would be minimal. Other assumptions used include the following: 1) grazing season lasts from November 1 to June 1 (210 d) for E+ tall fescue and Jesup AR542 from yr 2 to 21; 2) a stocking rate of 4.9 steers/ha; 3) Oklahoma City National Stockyards 10-yr average price (1986 to 1995) of 181-kg steer calves in October, 298-kg feeder calves in May for E+ tall fescue calves, and 355-kg feeder calves in May for Jesup AR542, using a $0.0882/45.4 kg of BW slide from the nearest average weight reported (Peel, 1996); 4) ADG of calves based on averages of the four research trials cited in this paper comparing E+ tall fescue to Jesup AR542 (0.60 and 0.88 kg, respectively); 5) profitability is based on a comparison of the value of gain to the cost of gain; 6) custom rates of equipment operation used for all planting, hay harvest, and chemical and fertilizer applications (Kletke and Doye, 1998); 7) internal rates of return using the net present value (6% annual percentage rate) of budgeted future annual returns for comparison to the cost of pasture establishment; 8) 20-yr life was assumed for new stand of Jesup AR542 as suggested by Vallentine (1989); and 9) average discounts for feeder cattle showing signs of fescue toxicosis at sale time are assumed to be $7.49/45.4 kg of BW (Mintert et al., 1988; Troxel et al., 2002).
The estimated agronomic cost of maintaining an established stand of E+ tall fescue for yr 1 to 21 is approximately $287.38/ha annually (Table 4). This estimate includes $75.80/ha for a blended fertilizer (17-17-17) spread in the fall and $39.14/ha for ammonium nitrate to be spread in the early spring. The hay costs are for cutting, raking, and round baling the summer growth. We estimated that this type of pasture would produce approximately 6,718 kg/ha in a summer with residual nitrogen from the winter fertilizer, and it costs approximately $11.64 to produce a 454-kg bale (Kletke and Doye, 1998). The total agronomic cost for establishing the Jesup AR542 pasture was $988.66/ha. Fertilizer costs included two applications of a blended product (17-17-17) at $75.80/ha each (336 kg/ha); one to be applied after planting the pearl millet and one to be applied after planting the Jesup AR542. There are also three applications of ammonium nitrate at $39.14/ha each (168 kg/ha), with all three to be applied on the pearl millet for hay production. The two treatments with herbicides ($22.22 each) are for glyphosate application. Hay-harvesting costs were much greater for yr 1 of establishing than for the E+ tall fescue pasture because we estimated that this pasture would produce 2.3 times more hay as pearl millet (Phillips, 1990). Seed costs were $2.43/kg of pearl millet seed and $8.82/kg of Jesup AR542 seed. The estimated agronomic costs of yr 2 to 21 of the Jesup AR542 stand were approximately $287.38/ha annually and identical to the E+ tall fescue cost.
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Table 4. Estimated costs and returns associated with maintaining E+ tall fescue or establishing a pasture of Jessup tall fescue infected with AR542 over a 21-yr period
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The costs estimated for maintaining the cattle totaled $464.74/ha annually (Table 4). Receiving costs were calculated using an actual cost of $35.00/steer (S. A. Gunter, unpublished data), and a daily cattle cost of $0.10/steer was to pay for labor and vehicle to supplement (free-choice mineral) and observe the cattle. Interest cost for the cattle was calculated by multiplying the steer purchase price by the annual percentage rate (5.7%). Cattle costs are the same for E+ tall fescue and Jesup AR542 because we assumed the stocking rate and management would remain essentially unchanged.
Income from hay production in yr 1 of establishment of the Jesup AR542 was 178% greater than income that was expected annually from yr 1 to 21 on E+ tall fescue and yr 2 to 21 on the Jesup AR542 (Table 4). The differences noted in return from the cattle between yr 1 to 21 on E+ tall fescue and yr 2 to 21 on the Jesup AR542 resulted from difference in steer ADG of 0.28 kg/d. Net return for the Jesup AR542 in yr 1 was 418% less than the annual net return for E+ tall fescue on yr 1 to 21, but the Jesup AR542 in yr 2 to 21 produced 62% greater net return annually than E+ tall fescue (Table 4). These estimates for differences in net returns account only for expected differences in ADG but do not account for changes in cattle quality. Market surveys have reported that feeder cattle showing signs of fescue toxicosis can be discounted as much as $10.32/45.4 kg of BW at sale time (Troxel et al., 2002). Future returns on investment for renovating a pasture from E+ tall fescue to Jesup AR542 are shown in Table 5. Based on our estimates, the stand would require 7 yr to break even and begin producing a return to the enterprise, and over the 21-yr period it would return a total of $395.19/ha. This first analysis assumes that the producer is growing cattle that are not showing signs of fescue toxicosis at sale time and not receiving a discount. However, NE+ tall fescues do not cause a reduction in quality of the cattle and may not negatively impact the potential sale price. Research from Kansas and Arkansas reports that cattle showing symptoms of fescue toxicosis are discounted an average of $4.65 or $10.32/45.4 kg of BW, respectively (Mintert et al., 1988; Troxel et al., 2002). If the data are reanalyzed with the average discount of $7.49/45.4 kg of BW included, the future return to investment is more favorable to suggest the establishment of Jesup AR542. Using this latter analysis, a producer could break even in 3 yr, and over the 21-yr period it would return a total of $1,652.53/ha. Lacy et al. (2003) compared the net present value of E+ and NE+ tall fescues over 10 yr and reported a $711.11/ha advantage for the NE+ tall fescue. Lacy et al. (2003) estimates were more optimistic than the yr-10 estimate ($83.21/ha) in the present analysis with no discount for fescue toxicosis. The difference between the present analysis and that of Lacy et al. (2003) mostly resulted from their lower estimates for establishment cost, which did not include the expense of a smother crop.
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Table 5. Future return on investment for renovating pastures and reseeding with Jesup tall fescue infected with AR542 for stocker cattle production compared to continued use of established E+ tall fescue pastureab
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Implications
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Novel endophyte-infected tall fescues seem to offer a solution to fescue toxicosis in stocker cattle; however, the ability of these new varieties to persist in many southern environments in the United States is open to question. Established stands of tall fescues infected with novel endophytes will allow for rates of gain by stocker cattle that are superior to those attained by cattle grazing endemically endophyte-infected tall fescues. However, because of the high cost of establishment for novel endophyte-infected tall fescues, analysis of returns on investments suggests that stands will require 3 to 7 yr to become profitable.
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Footnotes
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1 This article was presented at the 2003 Southern Section ASAS meeting as part of the Animal Science/Forages symposium "Southeast Beef Forage Systems." 
2 Correspondence: Southwest Research and Extension Center, 362 Highway 174 North (phone: 870-777-9702, ext. 107; fax: 870-777-8441; E-mail: sgunter{at}uaex.edu).
Received for publication February 11, 2003.
Accepted for publication July 2, 2003.
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Abstract
Introduction
