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© 2009 Plant Management Network.
Accepted for publication 12 December 2008. Published 27 February 2009.

Tall Fescue Persists and Cattle Perform Well on a Novel-Endophyte Association in the Southern Piedmont USA

Alan J. Franzluebbers, Ecologist, and Dwight H. Seman, Support Animal Scientist, USDA-ARS, Watkinsville, GA 30677; and John A. Stuedemann, Retired Animal Scientist, Comer, GA 30629

Corresponding author: Alan Franzluebbers. alan.franzluebbers@ars.usda.gov

Franzluebbers, A. J., Seman, D. H., and Stuedemann, J. A. 2009. Tall fescue persists and cattle perform well on a novel-endophyte association in the southern Piedmont USA. Online. Forage and Grazinglands doi:10.1094/FG-2009-0227-01-RS.

Abstract

Grazing and fertilization effects on long-term persistence of novel-endophyte-infected tall fescue (TF) have not been well documented. A field study was conducted for 6 years to assess; (i) persistence of TF under grazing conditions; and (ii) production and performance of yearling heifers on wild-endophyte-infected, novel-endophyte-infected, and endophyte-free TF associations fertilized with either inorganic N-P-K or broiler litter. Average daily gain (ADG) (1.5 ± 0.2 lb/day; mean ± standard deviation among 6 years) and cattle body weight (BW) gain on a yearly basis (487 ± 147 lb/acre) were as good with broiler litter as with inorganic fertilization (P > 0.1), although seasonal shifts occurred. ADG on TF pastures with novel endophyte (1.7 lb/day) was as good as, and in one year was even better than (P < 0.1), with endophyte-free association (1.6 lb/day), both of which were superior to ADG on wild-endophyte-infected tall fescue (1.2 lb/day). Persistence of TF with novel endophyte (73% basal area) was intermediate between wild endophyte (76%) and endophyte free (67%). With excellent ADG and stand persistence, novel-endophyte-infected TF should be recommended for establishment of new, sustainable, cool-season pastures in the Piedmont region and these pastures can be effectively fertilized with broiler litter.

Introduction

Tall fescue [Lolium arundinaceum (Schreb.) S.J. Darbyshire] is a widely disseminated grass grown around the world (4) and is considered the most important perennial, cool-season grass in the southeastern USA. It withstands grazing pressure by cattle and persists better than other cool-season perennial forages, especially during hot, dry conditions prevalent in this region. The superior persistence of TF could be related to a mutualistic association with a fungal endophyte [Neotyphodium coenophialum (Morgan-Jones and Gams) Glenn, Bacon, and Hanlin] first reported by Bacon et al. (1). The fungus produces various alkaloids, of which ergot alkaloids are associated with different toxic symptoms in cattle, sheep, and horses (11). These alkaloids may also be responsible for greater persistence of endophyte-infected than endophyte-free TF (2,6), perhaps the result of greater pest resistance and drought tolerance (9), as well as soil biological enhancement (10).

A novel strain of fungal endophyte that does not produce ergot alkaloids was selected and inserted into ‘Jesup’ TF (3). Persistence of novel-endophyte-infected TF was greater than endophyte-free TF in a short-term evaluation (3), but long-term data are needed. Under conditions of autumn stockpiling and intensive winter grazing at two locations in the Piedmont of North Carolina, persistence of TF was greater with novel-endophyte infection than without endophyte at the end of 3 years (5) and at the end of 5 years (12). In both of these studies, TF stand with novel endophyte tended to be lower than with wild endophyte, but not always statistically different.

Grassland cattle producers depending on TF in the southeastern USA are faced with a choice of TF-endophyte options: (i) poor animal performance and excellent stand persistence with wild-type endophyte infection; (ii) excellent animal performance and poor stand persistence with endophyte-free infection; and (iii) relatively unknown animal performance and stand persistence and substantial cost of pasture establishment with novel-endophyte infection. Our objective was to evaluate these three options in detail under near continuous stocking throughout 6 years at a Piedmont location in Georgia.

Pasture Establishment and Management

A 50-acre tract of land at the USDA Agricultural Research Service facility in Watkinsville, GA, was developed from 1998 to 2001 for this experiment. During the early 1990s, the land was naturalized herbaceous fallow with periodic mowing. Prior to that time and for several decades, land was privately owned and cropped using conventional cropping techniques. Fourteen paddocks (each 2.5 acres in size) were established with earthen berms surrounding them to collect water runoff through flumes at the lowest point. Residual plant growth was sprayed with glyphosate and paraquat and burned with fire prior to drilling TF seed in 8-inch rows at a rate of 20 to 25 lb/acre in November 2001 (following unsuccessful establishment the two years previously due to drought). Seven treatments (‘Jesup’ TF with different endophyte associations, fertilizer sources, and harvest management) with two replications each were successfully established and ready for grazing in April 2002. Inorganic fertilizer treatments received 80-40-80 lb N-P₂O₅-K₂O per acre in spring (February to March) and 80-0-0 lb N-P₂O₅-K₂O per acre in autumn (September to October). Broiler litter treatments received a target of 1.5 ton/acre in both spring and autumn, supplying the equivalent of 190-147-168 lb N-P₂O₅-K₂O per acre per year (we assumed that 80% of N would be available each year). A pool of 39 to 66 newly weaned Angus heifers (born in February to March) were made available for initiation of grazing in September to October each year (initial BW of 433 ± 37 lb). Assignment of cattle to paddocks was with a put-and-take method of three primary grazers per paddock and a variable number of secondary grazers. The three primary grazers were drawn from the middle weight distribution of the herd and secondary grazers were drawn from alternating lighter and heavier extremes. Forage mass (Fig. 1) (falling disk meter at 30 locations per paddock) and cattle weight (shrunk in Years 1 to 3, unshrunk in Years 4 to 6) were determined typically every 4 weeks. Forage was targeted for equal mass among all paddocks, varying with time due to limited herd size and seasonal growth of TF. Minimum forage mass was targeted as 670 lb/acre, at which point animals were removed until sufficient forage had developed for continuation of grazing. Animals removed from experimental paddocks were retained in a nearby pasture with endophyte-free TF and supplemented with hay and grain in winter when standing forage was not available.

Fig. 1. Forage mass as affected by TF-endophyte association from 2002 to 2007 at Watkinsville, GA. †, *, **, and *** indicate significance at P ≤ 0.1, P ≤ 0.05, P ≤ 0.01, and P ≤ 0.001, respectively (significance above symbols is for the comparison, wild endophyte vs others, and significance below symbols is for the comparison, endophyte-free vs novel endophyte). Data from 2002 to 2004 reported previously (7).

Persistence of Tall Fescue

Persistence of TF was evaluated by determining basal area of TF, weeds, and bare ground in late spring to early summer of each year (Table 1). Basal area was determined from visual estimation of the three components within a 2.8-ft² area at 30 different locations within a paddock by the same experienced technician. Sampling was stratified into three zones (0 to 100, 100 to 230, and 230 to 400 ft from shade and water sources), but we did not observe any differences in percentage ground cover among zones. Bare ground was 18 ± 10% (mean ± standard deviation among 7 sampling events) of the area, while weed coverage was 10 ± 9% of the area.

Table 1. Basal area of TF (%) as affected by the main effects of fertilizer source and endophyte association during the course of six years of continuous grazing at Watkinsville, GA. Data from 2002 to 2004 reported previously (7).

†, *, and ** indicate significance between means at P ≤ 0.1, P ≤ 0.05, and P ≤ 0.01, respectively.

Basal area of TF increased with time during the first 3 years, as reported previously (7), and stabilized at 73 ± 13% thereafter (Table 1). Pastures fertilized with broiler litter had lower basal area of TF than pastures fertilized with inorganic fertilizer in 2004, 2006, and when averaged across years. Fertilizer source results were not affected by endophyte association, and therefore, values presented in Table 1 reflect main effects only. When regressed on time, there was no indication of temporal divergence in TF development due to fertilizer source.

Basal area of TF was greater with novel-endophyte-infected pastures than with endophyte-free pastures in 2004, 2006, and when averaged across years (Table 1). At initiation of the study, basal area of TF was lowest with the novel endophyte association. Except at initiation, basal area of TF was not different between novel and wild endophyte associations. These data suggest that Jesup TF with novel-endophyte association is as persistent as with wild endophyte association and more persistent than without an endophyte. Our results from year-round grazing are in agreement with those found at the end of 3 to 5 years of stockpiled winter grazing in North Carolina (5,12), although differences in absolute ground cover occurred among studies. The consistency of results in these studies suggests that persistence of novel-endophyte-infected TF is superior to endophyte-free TF pastures.

Cattle Stocking

Stocking rate on a pasture (mean of 915 lb/acre; Table 2) was not affected (P > 0.1) by fertilization regime. Pastures supported a higher stocking rate in spring and summer (1033 lb/acre) than in autumn and winter (735 lb/acre). Lack of difference in stocking weight between fertilizer sources was consistent during the first 3 years (7) and the last 3 years of the study. Adjusted to the total time available within a season or year, 0.9 head/acre was stocked under both fertilization regimes. Grazing days were different among years, primarily in response to forage availability as a function of precipitation (Fig. 2). Pastures were stocked for 127 days in 2002, 263 days in 2003, 277 days in 2004, 253 days in 2005, 211 days in 2006, and 128 days in 2007. Stocking was 86 ± 18% of available days in spring, 51 ± 55% of available days in summer, 70 ± 16% of available days in autumn, and 24 ± 20% of available days in winter (mean ± standard deviation among years).

Table 2. Seasonal and yearly cattle stocking weight as affected by the main effects of fertilizer source and endophyte association during the course of six years of continuous grazing at Watkinsville, GA. Data from 2002 to 2004 reported previously (7).

† and * indicate significance between means at P ≤ 0.1 and P ≤ 0.05, respectively.

Fig. 2. Seasonal precipitation distribution among the 6 years of investigation at Watkinsville, GA. SPR is spring (21 March to 20 June), SUM is summer (21 June to 20 September), AUT is autumn (21 September to 20 December), and WIN is winter (21 December to 20 March).

Cattle stocking rate (Table 2) was not different between endophyte-free and novel-endophyte-infected TF pastures during any year or season. However, stocking rate was an average of 23% greater on pastures with wild endophyte than with novel endophyte. This treatment effect occurred in all years and across all seasons, except in winter, when forage availability was lowest. Wild endophyte had greater stocking rate than novel endophyte across years; the difference was 0.50 heifers/acre in spring, 0.24 heifers/acre in summer, 0.19 heifers/acre in autumn, and 0.07 heifers/acre in winter. Essentially no difference in stocking rate was found between pastures with novel endophyte and endophyte-free, indicating that they can be stocked to the same level.

Cattle Performance and Production

Average daily gain (ADG) on a yearly basis (mean of 1.51 lb/day; Table 3) was unaffected by fertilizer source. Seasonal differences in ADG occurred between fertilizer sources, with greater ADG on pastures fertilized with broiler litter than with inorganic fertilizer in summer and an opposite effect in winter. A difference in nutrient availability to pasture may have occurred, whereby mineralization of nutrients from broiler litter may have enhanced forage growth in summer and limited forage growth in winter in response to temperature as a controlling factor. Cattle body weight (BW) gain (mean of 487 lb/acre; Table 4) followed the same yearly and seasonal patterns with respect to fertilizer source as did ADG. These results suggest that organic fertilizer from broiler litter was as effective as inorganic fertilizer for pasture growth and subsequent cattle production, given ~20% greater total N input with broiler litter to account for incomplete mineralization.

Table 3. Seasonal and yearly ADG as affected by the main effects of fertilizer source and endophyte association during the course of six years of continuous grazing at Watkinsville, GA. Data from 2002 to 2004 reported previously (7).

†, *, **, and *** indicate significance between means at P ≤ 0.1, P ≤ 0.05, P ≤ 0.01, and P ≤ 0.001, respectively.

ADG was not different between endophyte-free and novel-endophyte-infected TF pastures when averaged across years (mean of 1.68 lb/day) (Table 3). However, ADG was marginally greater on novel-endophyte-infected than on endophyte-free pastures in 2007, a year in which year-long drought limited stocking to only 128 days. Whether the effect might have been drought induced or not needs further investigation. No seasonally differentiated effects on ADG occurred between endophyte-free and novel-endophyte-infected pastures. Overall, ADG and BW gain per acre (Table 4) on novel-endophyte-infected TF pasture were as good as on endophyte-free pasture.

Table 4. Seasonal and yearly BW gain per acre as affected by the main effects of fertilizer source and endophyte association during the course of six years of continuous grazing at Watkinsville, GA. Data from 2002 to 2004 reported previously (7).

†, **, and *** indicate significance between means at P ≤ 0.1, P ≤ 0.01, and P ≤ 0.001, respectively.

ADG on wild-endophyte-infected pasture was reduced by 30% compared to novel-endophyte-infected pasture, across years and seasons (Table 3). This depression in ADG occurred in all years of evaluation. Seasonally, ADG depression was 0.77 lb/day in spring (P < 0.001), 0.10 lb/day in summer (P = 0.30), 0.57 lb/day in autumn (P = 0.003), and 0.36 lb/day in winter (P = 0.007). This effect has been well documented in the literature (8, 11).

Since stocking rate was greater with wild than with novel endophyte, BW gain (mean of 484 lb/acre; Table 4) did not mirror ADG results. No difference in BW gain per acre occurred between wild-endophyte-infected and novel-endophyte-infected pastures, when averaged across years and seasons (Table 4). Mean BW gain was 514 lb/acre under novel endophyte and 454 lb/acre under wild endophyte (P = 0.11). BW gain per acre was marginally greater (P ≤ 0.1) under novel-endophyte-infected TF than under wild-endophyte-infected TF during the average of the first 3 years and during 2006. Seasonally, BW gain was greater with novel endophyte than with wild endophyte in spring (254 vs. 215 lb/acre, P = 0.09) and in autumn (146 vs. 109 lb/acre, P = 0.01), but lower with novel endophyte than with wild endophyte in summer (75 vs. 95 lb/acre, P < 0.001) and equal between novel- and wild-endophyte associations in winter (38 vs. 34 lb/acre, P = 0.20). BW gain per acre was lowest in winter, more a result of limited forage growth that restricted grazing days, than due to ADG. BW gain per acre was lower under novel endophyte than under wild endophyte in summer due to a lower stocking density resulting from limited forage availability, not because of a difference in ADG.

Our data confirm that ADG is positively affected in the presence of novel compared with wild endophyte during the main TF growth period in spring, as well as during the minor growth periods in autumn and winter. However, ADG was not affected by endophyte association in the dormant growth period in summer, which may have been due to lower ergot alkaloid concentration in TF forage during the heat of summer or simply a matter of forage substitution with growth and consumption of a small amount of various weedy forage invaders during this dormant period [e.g., crabgrass (Digitaria spp. Haller), foxtail (Alopecurus spp. L.), bermudagrass (Cynodon dactylon (L.) Pers.), etc.].

With near year-long stocking of cattle on TF pastures, a certain degree of compensatory BW gain per acre appears to have occurred with regard to the wild endophyte compared with novel (or free) endophyte. Lower BW gain per acre with wild than with novel endophyte during spring and autumn (due to a strong negative effect of wild endophyte on ADG) was partially compensated for by greater BW gain per acre with wild than with novel endophyte during summer (due to higher stocking rate and no difference in ADG). Based on a calf backgrounding period from weaning (½ year) until 1½ years of age, cattle BW gain was 469 ± 157 lb/acre (mean ± standard deviation among 6 years) on endophyte-free TF pasture, 487 ± 144 lb/acre on novel-endophyte-infected TF pasture, and 441 ± 171 lb/acre on wild-endophyte-infected TF pasture. During none of the 6 years was cumulative calf BW gain per acre different (P > 0.1) between endophyte-free and novel-endophyte-infected TF. Only in 3 years (i.e., 2002/03, 2005/06, and 2006/07) was there a marginally significant effect (P ≤ 0.1) of lower cumulative calf BW gain per acre when grazing wild-endophyte-infected compared with novel-endophyte-infected TF; two of those years occurred during short grazing years due to drought (Figs. 2 and 3), and therefore, ending weights occurred soon after the toxic period in spring. Depression of cumulative BW gain per acre with wild compared with novel endophyte was 14 ± 13% (mean ± standard deviation among 6 years) during this study.

Conclusions

Yearly ADG (1.5 lb/day) and BW gain (487 lb/acre) were as good with broiler litter fertilization as with inorganic fertilization. Cost of broiler litter was $100/acre, including nutrient analysis and a premium price to the supplier for meeting the standards of this research experiment, while the cost of inorganic fertilizer was $140/acre. Therefore, broiler litter was the most profitable cattle production scenario, because of the lower cost and broader spectrum of nutrients applied. ADG on TF pastures with the novel endophyte was as good as, and in one year was better than, endophyte-free association, both of which were superior to ADG on wild-endophyte-infected TF. With excellent ADG and stand persistence, novel-endophyte-infected TF pastures fertilized with broiler litter should be recommended for establishment of new, sustainable, cool-season pastures in the southern Piedmont USA.

Acknowledgment

This long-term research project has been supported by USDA-Agricultural Research Service (base funding and GRACEnet Project), the Office of Science (BER), United States Department of Energy, Grant No. DE-IA02-00ER63021, Madison County Cattlemen’s Association, and USDA-National Research Initiative, Soil Processes Program, Grant No. 2007-35107-17868. We gratefully acknowledge the excellent technical support provided over the years by Steve Knapp, Eric Elsner, C. J. O’Mara, Kim Lyness, Amanda Limbaugh, Josh Cown, Stephanie Steed, and Robert Sheats.

Literature Cited

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