PDF version
for printing

Impact
Statement

© 2007 Plant Management Network.
Accepted for publication 1 November 2007. Published 17 December 2007.

Agronomic Performance of Stockpiled Tall Fescue Varies with Endophyte Infection Status

Mary E. Drewnoski, Graduate Research Assistant, Matthew H. Poore, Professor and Extension Ruminant Nutrition Specialist, Erinn J. Oliphant and Brandon Marshall, Graduate Research Assistants, Department of Animal Science, and Jim T. Green, Jr., Professor Emeritus, Department of Crop Science, North Carolina State University, Raleigh 27695

Corresponding author: Mary E. Drewnoski. medrewno@ncsu.edu

Drewnoski, M. E., Poore, M. H., Oliphant, E. J., Marshall, B., and Green, J. T., Jr. 2007. Agronomic performance of stockpiled tall fescue varies with endophyte infection status. Online. Forage and Grazinglands doi:10.1094/FG-2007-1217-03-RS.

Abstract

New associations of tall fescue [Lolium arundinaceum (Schreb.) Darbysh] with non-toxic endophytes [Neotyphodium coenophialum (Morgan-Jones and Gams) Glenn, Bacon and Hanlin] that do not produce toxic ergot alkaloids have been developed and are commercially available. Tall fescue is often stockpiled in autumn for grazing during the winter; however, there are few data on the fall growth or nutritive value of fescue with the novel endophyte. Therefore, agronomic performance of autumn stockpiled endophyte-infected (E+), endophyte-free (E-), and novel endophyte-infected (EN) Jesup tall fescue was evaluated during five winters and the ergot alkaloid concentration of the stockpiled forage was measured during two winters. Addition of the novel endophyte improved fall growth compared with E-. After five winters, sward composition of E+ and EN did not differ, but both had more fescue than E-. Differences in nutritive value of the total sward due to endophyte status were small and were mainly caused by invasion of other plant species. Ergot alkaloid concentration of E+ decreased 81% from December (2349 ppb) to January (443 ppb). Agronomic characteristics of EN and E+ appear to be similar and both are suitable for stockpiling.

Introduction

In the mid-Atlantic region of the USA, autumn growth of tall fescue can be accumulated to extend grazing into the winter (12). The presence of the endophyte in tall fescue has been shown to improve agronomic traits (9), but is also the cause of poor animal performance due to production of ergot alkaloids (7). Hi-Mag tall fescue infected with a novel endophyte produced the same amount of stockpiled forage as the endophyte-free line, whereas Kentucky 31 endophyte-infected tall fescue had greater forage mass than both the endophyte-free or novel Hi-Mag (10). Endophyte status did not effect nutritive value or forage mass of stockpiled Jesup tall fescue in North Carolina (4). These studies, however, were relatively short (2 or 3 years) and did not measure long-term changes in sward composition. Therefore, the first objective of our study was to determine the effect of endophyte status on the composition and nutritive value of endophyte-infected, endophyte-free, and novel endophyte-infected tall fescue stands when stockpiled and intensively grazed over five consecutive winters.

Endophyte-infected fescue may contain toxic levels of ergovaline during December, which decrease during the winter (4,10). Ergovaline concentration has been used as an indicator of fescue toxicity, however, recent research suggests that total ergot alkaloid concentration maybe a better indicator because ergot alkaloids other than ergovaline may also contribute to toxic effects (6). Therefore, the second objective of our study was to determine the changes in total ergot alkaloid concentrations in endophyte-infected tall fescue over the winter.

Pasture Establishment and Management

The protocol for this study was approved by the Institutional Animal Care and Use Committee at North Carolina State University (#01-137). The experiment was set up in a randomized complete block design with four replications (2.5-acre pastures) of three treatments. Treatments were Jesup tall fescue that was either infected with wild-type toxic endophyte (E+), infected with a novel (AR542) endophyte (EN), or endophyte-free (E-). Stands were established at the Butner Beef Cattle Field Labortory (Butner, NC). The soil was a Georgeville silt loam (clayey, kaolinitic, thermic Typic Hapludults).

In July 1999, the existing canopy of A.U. Trumph tall fescue was harvested to a 2.5-inch stubble, and sprayed three weeks later with one application of glyphosate isopropylamine salt herbicide (0.97 lb a.i./acre). The sod was then disked, harrowed, and packed. In late November of 1999, the Jesup tall fescue seed was drilled at a rate of 19.6 lb/acre.

To allow for establishment of the stands the pastures were only clipped in the spring and fall of 2000. Each year from 2001 to 2005, plots were cut for hay in mid-August and then forage was allowed to accumulate for winter grazing. Nitrogen in the form of 30% urea ammonium nitrate was applied on 28 August 2001, 24 September 2002, 4 September 2003, 21 September 2004, and 5 October 2005 at a rate of 77, 86, 76, 85, and 51 lb/acre, respectively. Our target nitrogen application date was 1 September, however date of application was delayed in some years until favorable soil moisture and weather conditions were present. The stockpiled fescue was strip-grazed beginning 1 December of each year until 15 March 2002 (winter 1), 1 March 2003 (winter 2), 16 March 2004 (winter 3), 26 February 2005 (winter 4), and 16 February 2006 (winter 5). Growing cattle (560 lbs) were given a daily allotment of forage with a target post-graze height of 2 inches. Angus-cross steers were used during the first winter and heifers in subsequent winters. To ensure uniform utilization of available forage the strip size was adjusted based on the previous day’s residue. Due to differences in available forage, the fresh area offered each day differed among treatments and averaged 0.0053, 0.0066, 0.0060 acres/head (SE ± 0.0002) for E+, E- and EN, respectively.

A sample of 60 tillers was taken from each pasture in November 2001 and again in August 2006 to determine endophyte infection levels and the percentage of infected tillers producing ergot alkaloids. Tiller infection and ergot alkaloid analyses were completed by Agrinostics, Ltd. (Watkinsville, GA) using immunoblot and enzyme-linked immunosorbent assay (ELISA) techniques (1), respectively. The endophyte status of our stands was confirmed by initial tiller samples and all stands maintained their endophyte status over the course of the trial (Table 1).

Table 1. Percentage of tillers infected with endophyte and percentage of infected tillers that produced ergot alkaloids in swards of tall fescue that varied in endophyte status in winters 1 (2001) and 5 (2005).

Means within a column followed by different letters differ at P < 0.05.

 ^x E+ = endophyte infected; E- = endophyte-free; EN = novel endophyte-infected.

 ^y Standard error of mean.

 ^z Percentage of infected tillers that produced ergot alkaloids.

Forage Measurements and Analysis

A calibrated falling plate meter (18) was used to estimate forage mass in all pastures in mid-November of each year. Forage was clipped at ground level from nine (2.69 ft²) sampling sites, dried at 140°F for 72 h, and then weighed to determine the dry forage mass per acre. Forage mass of the clipped sites was related to plate meter readings at the same sites via linear regression to develop a calibration equation. This equation was used to predict the forage mass in each pasture from the average of 25 random falling plate meter readings.

In early December and every two weeks thereafter during each winter grazing period, forage samples were clipped 2 inches from ground level using battery-operated hand-held grass shears, at 10 randomly selected areas (0.69 ft²) per pasture, within the area that was estimated to be grazed in the next two weeks. Forage was sub-sampled and divided into two portions, one to determine nutritive value of the total sward and the other portion was used to determine species composition of the sward (on a dry matter basis) by hand separation. During winter 1, two plot replications of the portion used to determine species composition were pooled and then separated into three fractions consisting of green fescue, brown fescue and non-fescue species. During winters 2 through 5, forage for hand separation was not pooled among replications and was separated into four fractions consisting of green fescue, brown fescue, green non-fescue, and brown non-fescue. In winters 2 through 5, nutritive value of the fractions was determined monthly during the grazing period. Due to very small amounts of tissue, the brown non-fescue samples were pooled across replication by treatment within date and green non-fescue samples were pooled across replication and treatment within date for chemical analysis. Dry matter, ash, and crude protein (Kjeldahl N*6.25) were analyzed by methods outlined in (2). Neutral detergent fiber (NDF), acid detergent fiber (ADF), and lignin were determined sequentially (17). Hemicellulose was determined as the difference between NDF and ADF, and cellulose was determined as the difference between ADF and the 72% sulfuric acid residue. In vitro true dry matter digestibility (IVTDMD) was determined by a 48 h in vitro fermentation in vessels that contained McDougal’s buffer and strained ruminal fluid (16) and digestion was terminated with NDF extraction.

In winter 4 and 5, a third portion of the forage sampled was stored frozen until freeze dried and analyzed for ergot alkaloid concentration via ELISA technique (1). The ergot alkaloid concentration for all treatments was measured on December 6 and March 1 (winter 4) and December 7 and February 8 (winter 5). To characterize the decline of ergot alkaloid concentration in E+, samples were taken and analyzed monthly from December through February (winter 4) and December through March (winter 5).

Statistical analysis was conducted using a linear mixed models procedure (PROC MIXED) in SAS 9.1 (SAS Institute Inc., Cary, NC) as described in (11). The model included the fixed effects of treatment and winter and their interaction. Blocks were considered random effects. The effect of time on the nutritive value of the forage and ergot alkaloid concentration was evaluated by testing for linear and quadratic effects of sample date as well as associated interactions. Interactions that were greater than P = 0.20 were removed from the model. Species composition during winter 1 was analyzed separately from subsequent winters due to differences in the method by which samples were separated. Significant differences were defined as P ≤ 0.05.

Yield of Stockpiled Fescue

Forage mass differed among the treatments (P < 0.01) and by winter (P < 0.01) but the treatment by winter interaction was not significant (P = 0.11). Forage mass of E+ (3550 lb/acre) and EN (3416 lb/acre) did not differ (P = 0.09) but both were greater (P ≤ 0.01) than E- (3131 lb/acre, SE ± 76.4). In contrast, previous research indicated that the addition of a novel-endophyte to 'HiMag' tall fescue did not improve fall growth over HiMag E- (10). In a three-year study, Burns et al.(4) measured no differences in stockpiled forage yield among Jesup E-, E+ or EN tall fescue. Differences in yield among winters (P < 0.01) (Fig. 1) were due to variation in rainfall, temperature and fertilization date (Fig. 2) during the forage-accumulation phase (August through November). Precipitation during the accumulation phase of year 1 was less than half (7 inches) of the 30-year mean (16 inches). However, due to early fertilization yield was the greatest in year 1. The accumulation phase of years 2 and 3 were wetter than normal having 24 and 20 inches of rainfall, respectively. In year 2, heavy rainfall after nitrogen application may have reduced amount of nitrogen available for plant uptake causing low yields. The rainfall during the accumulation phase in years 4 and 5 (18 and 17 inches, respectively) was only slightly above the 30-year mean. However, due to low rainfall during September of year 5 nitrogen application was delayed until early October causing low yields.

Fig. 1. Initial forage mass of stockpiled Jesup tall fescue swards in winters 1 through 5. Bars with different letters differ at P < 0.05.

Fig. 2. Monthly climatological data for Durham, NC during 2001 through 2006 along with the 30-year mean. Durham North Carolina is approximately 12 miles from the research site. Data are from the National Oceanic Atmospheric Administration (13).

Species Composition of the Stands

The treatment by week interaction was not significant for any of the sward composition data therefore all data presented are the average across all sampling dates within winter. In winter 1, the fescue component of the sward averaged 87% and did not vary (P = 0.55) among treatments (Table 2). The percentage of the fescue that was green, however, differed among treatments (P < 0.01) (Table 2). Endophyte-free swards had the lowest percentage of the fescue that was green (31%), EN was intermediate (41%), and E+ (49%) had the highest. Dry weather during winter 1 may have increased the percentage of fescue that was brown in E- and EN. From August to December in 2001 the precipitation was 14 inches below the 30 year mean of 27 inches (Fig. 2).

Table 2. The percentage of fescue and of the fescue that was green in stockpiled tall fescue swards as influenced by endophyte status.

Means within a column followed by different letters differ at P < 0.05.

 ^v E+ = endophyte infected; E- = endophyte-free; EN = novel endophyte-infected.

 ^w Standard error of mean.

 ^x Winter 1 was analyzed separately from other winters due to differences in methods of data collection.

 ^y Endophyte status by winter interaction not significant (P > 0.20).

 ^z Percentage of the fescue in sward that was green.

The total percentage of fescue in the sward and the percentage of the fescue that was green varied among winters 2 through 5 (Table 2). There was no treatment by winter interaction (P > 0.20), therefore effects of treatment are presented across the four winters. In contrast to winter 1, the amount of fescue in the sward during winters 2 through 5 varied among treatments (P < 0.01) (Table 2). The percentage of the fescue that was green did not differ among the treatments (P = 0.71) (Table 2).

In winters 2 through 5, the non-fescue fraction of the sward was separated into brown non-fescue and green non-fescue (Table 3). The brown non-fescue species consisted mainly of crabgrass (Digitaria spp.) and johnsongrass (Sorghum halepense L.). The amount of brown non-fescue species differed by treatment (P < 0.01) being higher for E- (14%) than for E+ (8%) and EN (10%), which did not differ (P > 0.10).

Table 3. The percentage of fescue, of the fescue that was green, and non-fescue tissue of stockpiled tall fescue swards in winters 2 through 5. Data are averages of three endophyte statuses^w.

Means within a column followed by different letters differ at P < 0.05.

 ^w Endophyte status included endophyte infected, endophyte-free, and novel endophyte-infected.

 ^y Standard error of mean.

 ^z Percentage of the fescue in the sward that was green.

There was a significant treatment by winter interaction (P = 0.02) (Fig. 3) for the amount of green non-fescue species in the swards. Kentucky bluegrass (Poa pratensis L.) accounted for most of the green non-fescue fraction. In winter 2, treatments did not differ in the amount of green non-fescue in the sward. In winters 3, 4, and 5, however, the amount of green non-fescue in E- was higher than in E+ and EN, which did not differ. From winter 2 to 5, E- showed an increase in green non-fescue while E+ and EN did not.

Fig. 3. Percentage green non-fescue in stockpiled endophyte-infected (E+), endophyte-free (E-), and novel endophyte-infected (EN) Jesup tall fescue swards. Bars with different letters differ at P < 0.05.

The lower non-fescue fraction in both E+ and EN suggests a slight advantage in resistance to invasion by other plant species compared with E- swards. Crabgrass was common in E- stands and its presence may also have caused the lower yields in this treatment.

Nutritive Value of Fescue Fractions

The treatment by week interaction was not significant for any of the nutritive value measures (P > 0.20), therefore all data presented are the average across all dates within winter. The IVTDMD, NDF, and cellulose of green fescue differed slightly (less than one percentage unit) among treatments, whereas ADF and lignin did not (Table 4). The amount of fescue that was green decreased over the winter; however, the tissue that remained green retained high IVTDMD (85% or greater). The IVTDMD and lignin concentrations of the brown fescue fraction of the sward did not vary among treatments, whereas differences in ADF, NDF and cellulose were observed (Table 4).

Table 4. Nutritive value of the green and brown fescue fractions of stockpiled tall fescue swards that varied in endophyte status. Data are averages of winters 2 through 5.

Means within a column followed by different letters differ at P < 0.05.

 ^w E+ = endophyte infected; E- = endophyte-free; EN = novel endophyte-infected.

 ^x Standard error of mean.

 ^y In vitro true dry matter digestibility.

 ^z Endophyte status by winter interaction (P < 0.05).

Nutritive Value of the Total Sward

The treatment by week interaction was not significant for any of the nutritive value measures (P > 0.20), therefore all data presented are the average across all dates within winter. Nutritive value of the total sward varied by winter (Table 5), but was similar to other studies conducted in North Carolina (3,4,15). The IVTDMD of the total sward differed by treatment and there was a treatment by winter interaction (P = 0.03) (Fig. 4). The IVTDMD of the total sward differed among treatments in winters 1 and 3, but not in winter 2, 4, and 5 (Fig. 4). The fiber concentration of the total sward varied slightly due to treatment (Table 6). The lower digestibility and higher fiber concentration of E- was most likely caused by an increased amount of brown fescue in winter 1 as well as higher amounts of brown non-fescue species in the sward during winters 2 through 5. Brown non-fescue species had IVTDMD of 54.1% and NDF of 70.3%.

Fig. 4. In vitro true dry matter digestibility of stockpiled endophyte-infected (E+), endophyte-free (E-), and novel endophyte-infected (EN) Jesup tall fescue swards. Bars with different letters within year differ at P < 0.05.

Table 5. Nutritive value of stockpiled Jesup tall fescue in each winter. Data are averages of three endophyte statuses^w.

Means within a column followed by different letters differ at P ≤ 0.05.

 ^w Endophyte status included endophyte infected, endophyte-free, and novel endophyte-infected.

 ^x Standard error of mean.

 ^y In vitro true dry matter digestibility.

Table 6. Nutritive value of the total sward of stockpiled Jesup tall fescue swards that varied in endophyte status. Data are the averages of five winters.

Means within a column followed by different letters differ at P ≤ 0.05.

 ^w E+ = endophyte infected; E- = endophyte-free; EN = novel endophyte-infected.

 ^x Standard error of mean

 ^y In vitro true dry matter digestibility.

 ^z Endophyte status by winter interaction (P ≤ 0.05).

Crude protein of the total sward was higher for E- than for E+ and EN, which did not differ (Table 6). The higher CP concentration of the E- sward was probably due to the higher proportion of green and brown non-fescue in the stand which had a higher CP (16.4 and 12.7%, respectively) concentration than the green and brown fescue fractions (12.7 and 8.5%, respectively).

Over the course of winter, fiber concentration increased linearly, whereas CP and IVTDMD decreased linearly (P < 0.01) (Fig. 5). Quadratic effects of week were also observed for CP, NDF, and IVTDMD (P < 0.05) in the total sward.

Fig. 5. Change in crude protein (CP), invitro true dry matter digestibility (IVTDMD), neutral detergent fiber (NDF), and acid detergent fiber (ADF) of stockpiled Jesup tall fescue swards from early-December until mid-February in winters 1 through 5. There was a linear effect (P < 0.01) of time on CP, IVTDMD, NDF, and ADF and significant quadratic effects (P < 0.05) for CP, NDF, and IVTDMD.

Previous studies reported no differences due to endophyte status in nutritive value of both stockpiled Jesup (4) and Hi-Mag (10) tall fescue. Due to the large number of samples taken during this study, we were able to detect small differences (one percentage unit or less) in nutritive value of the fescue fractions and total sward. Although statistically significant, these small differences would most likely not lead to differences in animal performance.

Ergot Alkaloid Concentration

Ergot alkaloid concentration varied by winter (P = 0.03), treatment (P < 0.01), and week (P < 0.01) with a significant (P < 0.01) week by treatment interaction. Total sward ergot alkaloid concentration of E+ (2349 ppb) was higher (P < 0.01) than E- (291 ppb) and EN (189 ppb) in early December, whereas E- was higher (P = 0.02) than EN. At the end of the winter ergot alkaloid concentration of E+ (533 ppb) was higher (P < 0.01) than E- (4 ppb) and EN (1 ppb) which did not differ (P = 0.45).

Ergot alkaloid concentration of E+ did not vary by winter (P = 0.17) but there were week (P < 0.01) and week by winter (P = 0.05) interactions (Fig. 6). There was an 81% decrease in ergot alkaloid concentration from December to January. Total ergot alkaloid concentration in stockpiled fescue has not been previously reported, but the large decline from early-December to late-February in ergot alkaloid concentration observed in this study is similar to the decrease in ergovaline reported in other studies (4,10). Temperature has been shown to play an important role in fescue toxicity; high environmental temperatures exacerbate the elevated body temperature of animals grazing E+ causing them to reduce grazing time thereby contributing to decreased weight gain (14). In Oklahoma, average daily gain among steers grazing E+, E-, or EN Georgia 5 tall fescue in the fall did not differ, whereas in the spring gains were reduced on E+ compared with E- and EN fescue (8). The authors suggested that the lack of clear toxicity response in the fall may have been due the mild ambient temperatures. A three-year study conducted in Georgia reported that gains of cattle grazing Jesup tall fescue during the spring, summer and fall were lower for E+ than for E- or EN but in the winter gains did not differ (5). Thus, cool ambient temperature during winter may allow for utilization of stockpiled E+ without detrimental effects on animal performance despite elevated ergot alkaloid concentrations in December.

Fig. 6. Ergot alkaloid concentration of total sward of endophyte-infected stockpiled Jesup tall fescue over the winter during winters 4 and 5. Means with different letters within the same winter differ at P < 0.05.

Conclusions

Both E+ and EN fescue are suitable for stockpiling; however, use of E- is less desirable than E+ or EN because of lower yields and greater weed invasion with E-. Since ergot alkaloid toxicity is linked to elevated ambient temperature, grazing of EN fescue may be more beneficial when temperatures are higher; such as during the spring and early fall. Producers with E+ fescue stands should consider utilizing these pastures in the winter when ambient temperatures and ergot alkaloid concentrations are lower.

Literature Cited

1. Adcock, R. A., Hill, N. S., Bouton, J. H., Boerma, H. R., and Ware, G. O. 1997. Symbiont regulation and reducing ergot alkaloid concentration by breeding endophyte infected tall fescue. J. Chem. Ecol. 23:691-704.

2. AOAC. 1999. International Official Methods of Analysis, 16th edn. Assoc. Off. Anal. Chem., Arlington, VA.

3. Burns, J. C., and Chamblee, D. S. 2000. Summer accumulation of tall fescue at low elevations in the Piedmont: I. Fall yield and nutritive value. Agron. J. 92:211-216.

4. Burns, J. C., Fisher, D. S., and Rottinghaus, G. E. 2006. Grazing influences on mass, nutritive value, and persistence of stockpiled Jessup tall fescue without and with novel and wild-type fungal endophytes. Crop Sci. 46:1892-1912.

5. Franzluebbers, A. J., and Stuedemann, J. A. 2006. Pasture and cattle responses to fertilization and endophyte association in the southern Piedmont, USA. Agric. Ecosyt. Environ. 114:217-225

6. Gadberry, M. S., Denard, T. M., Spiers, D. E., and Piper, E. L. 2003. Effects of feeding ergovaline on lamb performance in a heat stress environment. J. Anim. Sci. 81:1538-1545.

7. Hill, N. S., Thompson, F. N., Dame, D. L., and Stuedemann, J. A. 1994. Antibody binding of circulating ergopeptine alkaloids in cattle grazing tall fescue. Am. J. Vet. Res. 55:419-429.

8. Hopkins, A. A., and Alison, M. W. 2006. Stand persistence and animal performance for tall fescue endophyte combinations in the south central USA. Agron. J. 98:1221-1226

9. Joost, R. E. 1995. Acremonium in fescue and ryegrass: Boon or bane? A review. J. Anim. Sci. 73:881-888.

10. Kallenbach, R. L., Bishop-Hurley, G. J., Massie, M. D., Rottinghaus, G. E., and West, C. P. 2003. Herbage mass, nutritive value, and ergovaline concentration of stockpiled tall fescue. Crop Sci. 43:1001-1005.

11. Littell, R. C., Henry, P. R., and Ammerman, C. B. 1998. Statistical analysis of repeated measures data using SAS procedures. J. Anim. Sci. 76:1216-1231.

12. Matches, A. G. 1979. Management. Pages 171-199 in: Tall fescue.  R. C. Buckner and L. P. Bush, ed. Agron. Monogr. 20. ASA, CSSA, SSSA, Madison, WI.

13. National Oceanic Atmospheric Administration. Climatological data annual summary North Carolina. Vol 106-111. 

14. Parish, J. A., McCann, M. A., Watson, R. H., Paiva, N. N., Hoveland, C. S., Parks, A. H, Upchurch, B. L., Hill, N. S., and Bouton, J. H. 2003. Use of non-ergot alkaloid-producing endophytes for alleviating tall fescue toxicosis in stocker cattle. J. Anim. Sci. 81:2856-2866.

15. Poore, M. H., Scott, M. E., and Green, J. T. Jr. 2006. Performance of beef heifers grazing stockpiled fescue as influenced by supplemental whole cottonseed. J. Anim. Sci. 84:1613-1625.

16. Tilley, J. M., and Terry, R. A. 1963. A two-stage technique for in vitro digestion of forage crops. J. Brit. Grass. Soc. 18:104-111.

17. Van Soest, P. J., Robertson, J. B., and Lewis, B. A. 1991. Methods for dietary fiber, neutral detergent fiber and nonstarch polysaccharides in relation to animal nutrition. J. Dairy Sci. 74:3583-3597.

18. Vartha, E. W., and Matches, A. G. 1977. Use of a weighted-disk measure as an aid in sampling the herbage yield on tall fescue pastures grazed by cattle. Agron. J. 69:888-890.