- Email: [email protected]
Stocking Rate Effects on Steer Performance for Two Methods of Alleviating Fescue Toxicosis1
Recovery Animal from Fescue Toxicosis The Professional Scientist 15:245–252
245
Rate Effects on Steer Stocking Performance for Two Methods of Alleviating Fescue Toxicosis1
G. E. AIKEN*,2 and E. L. PIPER† *USDA-ARS, Dale Bumpers Small Farms Research Center, Booneville, AR 72927 and †Animal Science Department, University of Arkansas, Fayetteville, AR 72701
d. Average daily gain for steers fed eastern gamagrass during the compensation phase declined linearly (P<0.05) as Generally, grazing endophyte-infested tall fescue (Festuca arundinace Schreb.) stocking rate increased, but ADG for steers fed tall fescue plus the broiler in the late spring and summer is not litter-corn mixture tended to increase recommended because of the effects of (P<0.10) as stocking rate increased. As a fescue toxicosis on cattle weight gains, result, ADG and live weight gain which can be extreme. For steers (kilograms per hectare) with heavier conditioned to graze tall fescue in the early spring, stocking rate (3, 4, 5, and 6 stocking rates were higher for steers fed tall fescue plus the broiler litter-corn steers/ha) effects were evaluated for two mixture, whereas the responses at a methods designed to avoid poor cattle lighter stocking rate were higher for performance during the late spring and steers fed eastern gamagrass. At the summer (compensation period). The conclusion of the compensation phase in evaluation was conducted in 1997 and 1998, steers fed tall fescue plus the 1998. During the compensation phase, broiler litter-corn mixture had lower one replicate of each stocking rate was (P<0.05) serum prolactin levels, and a randomly assigned to 1-ha pastures of eastern gamagrass (Tripsacum dactyloides higher (P<0.05) proportion of steers fed tall fescue had rough hair coats compared L.), and the other replicate of each stocking rate remained on tall fescue; the with those fed eastern gamagrass. Results of this study show that, for steers steers were fed a 1:1 mixture of broiler litter and corn at 2.27 kg as fed/steer per grazing tall fescue pastures, either eastern gamagrass or supplementation with a broiler litter-corn mixture can provide acceptable performance, but responses are affected by grazing pressure. Symptoms of fescue toxicosis can 1 Names are necessary to report factually on still occur, however.
Abstract
available data; however, the USDA does not guarantee or warrant the standard of the prod- (Key Words: Cattle, Animal Gain, uct, and the use of the name by the USDA Fescue Toxicosis.) implies no approval of the product to the exclusion of others that may also be suitable. 2To
Introduction
Reviewed by K. P. Coffey and A. D. Howes.
Tall fescue is a cool-season perennial grass that is widely adapted and
whom correspondence should be addressed: [email protected]
can persist under poor management. The grass has not had widespread popularity because cattle grazing tall fescue can exhibit symptoms of elevated body temperature, retainment of rough hair coats, and poor growth (17, 24, 29, 30). These symptoms, collectively referred to as fescue toxicosis, are associated with the consumption of toxic alkaloids that are produced by the fungal endophyte (4) Neotyphodium coenophialum (11). Fescue toxicosis is most severe and consequential to calf weight gains at the onset of high ambient temperatures and humidity in the late spring and summer (26, 28, 30). Poor growth and market value of feeder calves exhibiting fescue toxicosis have prevented the wide use of tall fescue for stocker production (16). Problems associated with grazing feeder calves on tall fescue could be reduced or possibly alleviated if the toxins in the diet were diluted by feeding hay or concentrate feeds (2, 5) or if cattle were moved to a warmseason perennial grass pasture during the warm season (9). Steers switched to endophyte-free tall fescue from endophyte-infested tall fescue have increased DMI and exhibited compensatory weight gains (27, 28, 30). Aiken et al. (2) found that steers grazing infested tall fescue and fed a mixture of broiler litter and ground
246
Aiken and Piper
eastern gamagrass were the same for 1997 and 1998 to assess effects of summer grazing treatments on tall fescue pastures. Steers grazing tall Item 1997 1998 fescue during the compensation phase were fed a 1:1 (as fed) mixture N, % 1.8 3.2 of broiler litter and ground corn at a P, % 0.8 1.1 rate of 2.27 kg (as fed)/steer per d K, % 1.4 1.9 (Table 1). This quantity of the Ca, % 1.2 1.8 broiler litter-corn mixture correMg, % 0.4 0.4 sponded to initial consumptions of S, % 0.3 0.4 0.8 and 0.9% BW, respectively, in Fe, mg/kg 6051 51 Mn, mg/kg 601 431 1997 and 1998. The broiler litters fed Zn, mg/kg 302 347 in each of the 2 yr were collected Cu, mg/kg 339 484 from the same broiler house. There was considerable variation in compoaA mineral and vitamin supplement was offered for ad libitum intake to the steers sition (Table 1); however, the litter on tall fescue plus the broiler litter-corn mixture and steers on eastern gamagrass fed in 1998 was collected following treatments that contained Ca (min. 12.0%, max 14.0%), P (min. 12.0%), Na (min. six batches of birds, and the litter fed 4.6%, max. 5.9%), Mg (max. 1.25%), K (min 1.25), Cu (min. 21 ppm), Se (min. 18 in 1997 was collected following only ppm), Zn (min. 300 ppm), vitamin A (441,000 IU/kg), vitamin D3 (99,225 IU/kg), three batches of birds. Feed value of and vitamin E (33 IU/kg). litter is influenced by the number of batches preceding litter harvest (23, 31). Litter in each year was deepstacked, following procedures that corn (1:1; as fed) for ad libitum were recommended by Ruffin and intake had similar ADG to those McCaskey (23) for composting broiler The grazing study was conducted grazing non-infested tall fescue with litter. Samples of the feed mixture in 1997 and 1998 near Booneville (35° were analyzed for minerals using a no supplement. Goetsch (12) reported a twofold increase in ADG for 5' N; 94° 0' W) in northwest ArkanSpectro Model D ICP (Spectro Anasas. The experimental site was on a calves fed infested tall fescue when lytical Instruments, Fitchburg, MA). Leadvale silt loam (fine-silty, siliceous, A mineral-vitamin supplement was ground corn was also fed at 0.75% thermic Typic Fragiudult) soil. Two BW. Broiler litter in a mixture with offered for ad libitum intake in each replicates of four stocking rates (3, 4, pasture to provide trace minerals corn has potential use as low-cost feedstuff (2, 10), particularly in areas 5, and 6 steers/ha) were assigned to (Table 1). eight 1.0-ha pastures of endophytewith extensive poultry production. The steers were implanted with Aiken et al. (2) showed that a broiler infested Kentucky-31 tall fescue in a Synovex-S® (Fort Dodge Animal litter-corn mixture could provide cost- completely randomized design. Health, Fort Dodge, IA) and dewThirty-six yearling steers (25 to 50% effective increases in ADG for steers ormed with ivermectin® (Merck, Inc., Brahman) were randomly assigned to Whitehouse Station, NJ) when initial fed endophyte-infested tall fescue when the corn cost is below $150.00/ stocking rates and pastures in each weights were taken for the conditionyear. The steers grazed the tall fescue ing phase; then, steers were detonne. A grazing study was conducted with the objective of compar- pastures for 6 d to ensure gut fill with wormed again with ivermectin® tall fescue prior to weighing ing stocking rate effects on growth during the compensation phase at 28 unshrunk at the initiation of a performance of steers that were d of grazing. The compensation conditioned to infested tall fescue in conditioning phase. The conditionphase was initiated on May 27, 1997 ing phase was initiated on March 20, (68th d of the conditioning phase) early spring and then, in late spring 1997 (initial steer weight = 276 kg; SE and on June 4, 1998 (56th d of the and summer, were either fed daily a 1:1 (as fed) broiler litter-corn mixture = 18) and on April 9, 1998 (initial conditioning phase). Duration of steer weight = 257 kg; SE = 16). or were moved to pastures of eastern the compensation phase was 76 d in A compensation phase followed gamagrass. Eastern gamagrass is a 1997 and 77 d in 1998. Two meathe conditioning phase by randomly surements were taken at the concluwarm-season perennial grass that is assigning one replicate of each native to most of the eastern U.S. sion of the compensation phase in stocking rate to four 1.0-ha pastures (14) and has potential for high 1998 (August 20) as determinants of of ‘Pete’ eastern gamagrass. Stocking fescue toxicosis. Serum prolactin was productivity (1, 3) and moderate rate assignments to tall fescue and nutritive value (1, 15). measured at the start and conclusion
TABLE 1. Nutrient composition of the broiler litter and ground corn mixtures (DM basis)a.
Materials and Methods
Recovery from Fescue Toxicosis
of the compensation period as a marker for fescue toxicosis (18). Blood samples were collected from the caudal vein at the base of the tail, and serum was obtained from centrifugation and then frozen. The serum was subsequently assayed for prolactin by a double antibody immunoassay (13). Second, hair coat condition of individual steers was rated and recorded as being either sleek, rough, or transitional (i.e., some roughness of hair coat over the rump and shoulder regions). Tall fescue pastures were fertilized on March 7, 1997 with N (67 kg/ha) and then on September 17 with N (84 kg/ha), P (36 kg/ha), and K (69 kg/ ha) and were fertilized on April 1, 1998 with N (84 kg/ha). Eastern gamagrass pastures were fertilized on May 7, 1997 with N (112 kg/ha), P (47 kg/ha), and K (93 kg/ha) and were fertilized on April 15, 1998 with N (112 kg/ha). The tall fescue pastures were mown in early September 1997 to remove accumulated herbage and to provide equal pasture heights at the onset of the fall and spring growth periods. Herbage mass for tall fescue was monitored during the study following procedures described by Bransby et al. (8). Disk meter height was recorded for 50 random locations in each pasture at 14-d intervals. Herbage was also clipped to ground level beneath the disk for two locations within each pasture at 28-d intervals. These samples were dried at 60° C in a forced-air oven for 48 h and weighed for calculation of regression equations that regressed DM per unit of land area over disk meter height. Herbage mass for eastern gamagrass was also measured at 14-d intervals by mowing a 0.9-m ´ 6.1-m area with a Jeri® mower (Year-A-Round CAB Corp., Mankato, MN) at three locations in each pasture. Wet herbage from the harvest strip was weighed and subsampled. Subsamples were dried at 60° C for 48 h in a forced-air oven to calculate herbage mass (kilograms of DM per hectare) as an average of the three locations within each pasture.
247
Figure 1. Relationships between stocking rate (SR) and herbage mass (HM) for steers on tall fescue during the conditioning (A) and compensation (B) phases and for steers on eastern gamagrass during the compensation phase (B).
Average daily gain and live weight gain per hectare (kilograms per hectare) were calculated for each phase and analyzed by examining year and treatment as dummy variables and evaluating stocking rate as a regression variable with deviations from the regression line as the error term (7, 21). The PROC MIXED procedure (20) was used on serum prolactin concentrations of indi-
vidual animals to analyze method and time effects during the compensation phase in 1998. Percentage rough hair coat conditions were analyzed using the Chi Square test (25) to determine association between this hair coat score with either of the two treatments imposed during the compensation phase. Herbage mass data for tall fescue and eastern gamagrass were analyzed separately
248
for stocking rate effects because the data were collected using different methods for the two grasses.
Aiken and Piper
gamagrass mass with increased stocking rate. Steer Performance. Steer ADG during the conditioning phase was relatively high in both 1997 (overall ADG = 0.99 kg/d; SE = 0.1) and 1998 Herbage Mass. Mean herbage (overall ADG = 0.59; SE = 0.06), but a mass (kilograms of DM per hectare) higher (P<0.01) y-intercept for 1997 during the conditioning phase than for 1998 indicated a trend of declined linearly (P<0.05) as stocking higher ADG for that year. The rate increased; the rate of decline was conditioning phase in 1998 was similar (P=0.41) across years (Figure initiated and terminated later than 1A). The y-intercept was higher in 1997 and, therefore, encountered (P<0.01) for 1998 than for 1997, higher ambient temperatures [average indicating that there was a trend for = 27° C (80° F)] than did the conditall fescue mass to be higher in 1998. tioning phase in 1997 [average = 23° This probably was due to the higher C (73° F)]. Therefore, although there N rates that were applied to the tall was greater herbage mass in 1998, fescue pastures in 1998. higher temperatures for that year For the compensation period, likely exacerbated the effect that stocking rate and year effects intertoxicosis had on steer performance. acted (P<0.05) to affect tall fescue Steer ADG was not affected by mass (Figure 1B). The linear decline stocking rate (P=0.82) in either year. in herbage mass with increased Although herbage mass was lower stocking was steeper (P<0.05) for 1997 with heavier stocking, it apparently than for 1998. Steep declines in tall was high enough with these stocking fescue mass with heavier stocking was rates to not limit steer weight gain. anticipated for this period because Unpublished grazing research on growth of the cool-season perennial endophyte-infested tall fescue has grass is typically minimal during the shown weak responses of ADG to hot and humid summer months. stocking rate (D. I. Bransby, Auburn Again, higher soil fertility in 1998 University, Agronomy and Soils might have stimulated some grass Department, Auburn, AL 36849, growth, especially during periods personal communication). Tall when there was adequate soil moisfescue tissues differ in ergovaline (a ture. The tall fescue pastures that toxic alkaloid) concentrations. The were grazed in the summer were not ranking order from highest to lowest visually observed to deteriorate (i.e., is seedheads, stems and sheaths, and weed encroachment), which indileaf blades (22). Belesky and Hill (6) cated that feeding the broiler litterreported alkaloid concentrations of 1 corn mixture at the quantities offered to 5 µg/g DM for two genotypes of resulted in forage consumptions low infested tall fescue and further enough to not severely stress the tall showed leaf sheath tissue to contain fescue. about twice the alkaloid concentraEffects of stocking rate (P=0.26), tion as did leaf blade tissue. High year (P=0.38), or their interaction concentrations of seedhead, stem, (P=0.35) were not detected on herband sheath tissues in lightly stocked age mass of eastern gamagrass. Wide herbage may result in higher conplant spacings and uneven grazing of sumption of alkaloids. Frequent eastern gamagrass made it difficult to grazing promotes leaf blade growth, obtain the precise measurement which can result in lower alkaloid needed to determine treatment effects concentrations in the overall herbage (1). Removing the stocking rate by (6); however, under this condition, year interaction from the statistical animal performance can be limited model provided results that indicated by restricted intake because of low a trend (P<0.10) of reduced eastern herbage mass.
Results and Discussion
High steer performance observed during the conditioning phase might have been related to cooler temperatures as well as lower concentration of ergovaline in the forage grazed in April compared with warmer temperature conditions and higher ergovaline concentrations in the forage grazed in June (22). At the end of the conditioning phase, a high proportion of the steers were visually observed to retain rough hair coats. At the conclusion of the conditioning phase, serum prolactin levels of these steers were approximately seven times lower than those taken from the same steers following 28 d (July 2) on the two treatments during the compensation phase. Normally, steers on non-toxic diets bled on similar dates have similar prolactin levels (19). These data indicate that, at the end of the conditioning phase, the steers were demonstrating several toxicosis symptoms. Average daily gain during the compensation phase in both years responded similarly (P=0.19) to stocking rate; however, the y-intercepts indicated that there was a tendency for higher (P<0.10) ADG in 1997 when herbage masses were generally lower. There was a stocking rate by method interaction (P<0.05) on steer ADG during the compensation phase (Figure 2A). Steer ADG on eastern gamagrass showed a typical linear decline (P<0.05) as stocking rate increased. Aiken (1) did not observe a stocking rate effect on ADG following 84 d of grazing eastern gamagrass, but the steers were not subjected to carry-over effects from grazing infested tall fescue in the spring. Aiken (1) further reported an ADG of 0.81 kg/ d, which is within the range of ADG measured in the present study. Thus, in the present study, performance of steers fed eastern gamagrass apparently was not adversely affected by grazing infested tall fescue in the spring. There was a trend (P<0.10) for ADG to increase as stocking rate increased for steers fed tall fescue plus
Recovery from Fescue Toxicosis
Figure 2. Relationships between stocking rate (SR) and ADG (A) and between SR and liveweight gain per hectare (B) for steers on tall fescue plus the broiler litter-corn mixture and for steers on eastern gamagrass during the compensation phase.
a broiler litter-corn mixture; this is atypical for results of most stocking rate experiments (7, 21). As previously discussed, there might have been reduced concentrations of alkaloids in the diet as stocking rate increased; thus, combined with the broiler litter-corn mixture, there could have been a considerable boost in diet quality. It should be men-
tioned, however, that heavier stocking rates than those used in this study would likely have resulted in low enough herbage masses to limit steer performance. Trends for the two regression lines indicated that ADG was higher for steers fed eastern gamagrass at lighter stocking rates and that ADG was higher for steers fed tall fescue plus the broiler litter-
249
corn mixture at heavier stocking rates. There were linear increases in live weight gain per hectare as stocking rate increased during the compensation phase, but the responses to stocking rate differed (P<0.05) between steers fed eastern gamagrass and those fed tall fescue plus the broiler litter-corn mixture (Figure 2B). The slope of the regression line was steeper (P<0.05) for steers fed tall fescue plus the broiler litter-corn mixture than for steers fed eastern gamagrass. Similar to ADG, trends in the regression lines indicate that live weight gain per hectare was favored by eastern gamagrass with lighter stocking rates but was favored by tall fescue plus the broiler littercorn mixture with heavier stocking rates. Symptoms of Toxicosis. As previously discussed, serum prolactin concentrations at the initiation of the compensation phase in 1998 were low. The grazing of infested tall fescue by cattle has been shown to suppress serum prolactin (1, 19). Reduced serum prolactin is, therefore, a symptom of fescue toxicosis; however, prolactin has not been directly related to the incidence of fescue toxicosis (19). Interactions of other hormones with the endotoxins have been implicated as the contributing factors causing toxicosis (29, 30), which suggests that reductions in serum prolactin in cattle exhibiting fescue toxicosis may be in response to changes in concentrations of other hormones that are inducing fescue toxicosis. Serum prolactin levels in steers under the two compensation methods increased at different rates (P<0.01) from baseline measurements taken initially for the compensation phase (Figure 3). Levels for steers grazing eastern gamagrass were higher than those for steers grazing tall fescue plus the broiler litter-corn mixture on July 2 (P<0.001) and August 20 (P<0.05). Among animal variation for the July 31 sample date was too high to detect differences
250
Aiken and Piper
Implications Results of the study indicate that weight gains of feeder steers grazing tall fescue in the late spring and summer can be improved if the steers are either moved to eastern gamagrass or fed daily a 1:1 broiler litter-corn supplement in a quantity of at least 0.8% BW (as fed). The extent of the enhancement of weight gains cannot be determined because a control treatment, tall fescue only, was not examined during the compensation phase because it was deemed too detrimental to the animals and pastures and because such effects have already been well documented. It can be assumed, however, that the combined effects of the endophyte and low herbage masses for this type of treatment would have had detrimental effects on steer performance. Trends in the regression lines for ADG and live weight gain per hectare indicate that fescue plus the broiler litter-corn mixture provided higher steer performance with moderate to heavy stocking rates and that eastern gamagrass provided higher performance with lighter stocking rates. Figure 3. Relationships between sample date and serum prolactin concentrations during the The two methods of reducing the compensation phase for steers on tall fescue plus the broiler litter-corn mixture and for steers adverse effects of fescue toxicosis in on eastern gamagrass. Baseline measurements were taken on June 4 at the initiation of the the late spring and summer provide phase. Standard error bars and P values are provided for the difference between the two options for extending the time that treatments. The measurements were taken in 1998. cattle can remain on pasture for extra backgrounding for the feedlot or to wait for suitable market conditions. One problem, however, is that a was probably a reflection of the trend certain portion of calves, particularly (P=0.24). Therefore, movement of toward a higher percentage of steers those that remain on tall fescue and steers from tall fescue to eastern with rough hair coats when those are fed the broiler litter-corn mixture, gamagrass was more effective in steers were grazing tall fescue and fed can still exhibit symptoms of toxicoraising serum prolactin levels than it the broiler litter-corn mixture comsis and, therefore, have reduced was in allowing steers to remain on pared with steers grazing the eastern market values. Therefore, fescue tall fescue while feeding the broiler gamagrass. Aiken et al. (2) reported toxicosis cannot be completely litter-corn mixture. There was no avoided for cattle fed a broiler litterstocking rate effect (P=0.24) on serum that approximately 38% of steers grazing infested tall fescue and fed corn mixture and grazing tall fescue prolactin levels for either of the two the broiler litter-corn mixture for ad in the summer. treatments. libitum intake had rough hair coats. Distributions of hair coat ratings It was concluded that some cattle at the conclusion of the compensamay be too sensitive to the alkaloids tion phase in 1998 (Figure 4) were The authors express appreciation for dilution of alkaloids in the diet to different (P<0.05) between steers eliminate fescue toxicosis completely. to Sam Tabler of USDA-ARS for grazing tall fescue plus the broiler providing advice and technical litter-corn mixture and steers grazing Results of the present study support support to the project and to Tamara this conclusion. eastern gamagrass. This difference
Acknowledgments
251
Recovery from Fescue Toxicosis
7. Bransby, D. I., B. E. Conrad, H. M. Dicks, and J. W. Drane. 1988. Justification for grazing intensity experiments: Analyzing and interpreting grazing data. J. Range Mange. 41:274. 8. Bransby, D. I., A. G. Matches, and G. F. Krause. 1977. Disk meter for rapid estimation of herbage yield in grazing trials. Agron. J. 69:393. 9. Brown, M. A., A. H. Brown, Jr., W. G. Jackson, and J. R. Miesner. 1997. Preweaning performance of Beefmaster- and Brahmansired calves from Angus and Brahman cows on three forage systems. Prof. Anim. Sci. 13:90. 10. Fontenot, J. P., and K. E. Webb, Jr. 1975. Health aspects of recycling animal wastes by feeding. J. Anim. Sci. 40:1267. 11. Glenn, A. E., C. W. Bacon, R. Price, and R. T. Hanlin. 1996. Molecular phylogeny of Acremonium and its taxonomic implications. Mycologia 88:369. 12. Goetsch, A. L. 1989. Effects of supplementation on feed intake, digestion and performance by cattle consuming endophyteinfected tall fescue. In Proc. Ark. Fescue Toxicosis Conf. C. P. West (Ed.). p. 17. Ark. Exp. Stn. Spec. Rep. 140. Fayetteville, AR. 13. Henson, M. C., E. L. Piper, and L. B. Daniels. 1987. Effects of induced fescue toxicosis on plasma tissue catecholamine concentrations in sheep. Domest. Anim. Endocrinol. 4:7. 14. Hitchcock, A. S. 1951. Manual of the grasses of the United States (2nd Ed.). USDA Misc. Publ. No. 200., Washington DC.
Figure 4. Percentages rough, sleek, and transitional hair coats at the conclusion of the compensation period in 1998 for steers on tall fescue plus the broiler litter-corn mixture and for steers on eastern gamagrass .
Denard of the University of Arkansas for conducting laboratory analyses.
2. Aiken, G. E., D. M. Ball, E. L. Piper, and C. P. West. 1998. Performance of steers fed a broiler litter-corn mixture on endophyteinfested and non-infested tall fescue. Prof. Anim. Sci. 14:51. 3. Anderson, R. C. 1985. Aspects of germination ecology and biomass production of eastern gamagrass (Tripsacum dactyloides L.). Bot. Gaz. 146:353.
Literature Cited 1. Aiken, G. E. 1997. Temporal effects on steer performance and nutritive values for eastern gamagrass grazed continuously for different durations. J. Anim. Sci. 75:803.
4. Bacon, C. W., J. K. Porter, J. D. Robbins, and E. S. Luttrell. 1977. Epichloe typhina from tall fescue grasses. Appl. Environ. Microbiol. 35:576. 5. Ball, D. M. 1984. An overview of fescue toxicity research. Auburn Vet. 39:66. 6. Belesky, D. P., and N. S. Hill. 1997. Defoliation and leaf age influence on ergot alkaloids in tall fescue. Ann. Bot. 79:259.
15. Horner, J. L., L. J. Bush, G. D. Adams, and C. M. Taliaferro. 1985. Comparative nutritional value of eastern gamagrass and alfalfa hay for dairy cows. J. Dairy Sci. 68:2615. 16. Hoveland, C. S. 1993. Importance and economic significance of the Acremonium endophytes to performance of animals and grass plant. Agric. Ecosys. Environ. 44:3. 17. Hoveland, C. S., S. P. Schmidt, C. C. King, Jr., J. W. Odom, E. M. Clark, J. A. McGuire, L. A. Smith, H. W. Grimes, and J. L. Holliman. 1983. Steer performance and association of Acremonium coenphialum fungal endophyte on tall fescue pasture. Agron. J. 75:821. 18. Jacobson, D. R., W. M. Miller, and D. M. Seath. 1963. Nature of fescue toxicity and progress toward identification of the toxic entity. J. Dairy Sci. 46:416. 19. Krag, H., and D. Schams. 1974. Prolactin release in cattle. J. Reprod. Fertil. 39:463. 20. Littel, R. C., G. A. Milliken, W. W. Stroup, and R. D. Wolfinger. 1996. SAS System for Mixed Models. SAS Institute, Inc., Cary, NC. 21. Riewe, M. E. 1961. Use of the relationship of stocking rate to gain of cattle in an experimental design for grazing trials. Agron. J. 53:309.
252
22. Rottinghaus, G. E., G. B. Garner, C. N. Cornell, and J. L. Ellis. 1991. HPLC method for quantitating ergovaline in endophyteinfested tall fescue: Seasonal variation of ergovaline levels of stems with leaf sheaths, leaf blades, and seed heads. J. Agric. Food Chem. 39:112. 23. Ruffin, B. G., and T. A. McCaskey. 1990. Broiler litter can serve as a feed ingredient for beef cattle. Feedstuffs 62:13. 24. Schmidt, S. P., and T. G. Osborn. 1993. Effects of endophyte-infected tall fescue on animal performance. Agric. Ecosys. Environ. 44:233. 25. Steel, R.G.D., and J. H. Torrie. 1980. Principles and Procedures of Statistics: A Biometrical Approach. McGraw-Hill, New York, NY.
Aiken and Piper
26. Strickland, J. R., J. W. Oliver, and D. L. Cross. 1993. Fescue toxicosis and its impact on animal performance. Vet. Human Toxicol. 35:454. 27. Stuedemann, J. A., D. L. Breedlove, K. R. Pond, D. P. Belesky, L. P. Tate, Jr., F. N. Thompson, and S. R. Wilkinson. 1989. Effect of endophyte (Acremonium coenphialum) infection of tall fescue and paddock exchange on intake and performance of grazing steers. In Proc 16th Int. Grassl. Congr. p 1243-1244. Nice, Fr. 28. Stuedemann, J. A., and C. S. Hoveland. 1988. Fescue endophyte: History and impact on animal agriculture. J. Prod. Agric. 1:39. 29. Stuedemann, J. A., S. R. Wilkinson, D. P. Belesky, O. J. Devine, D. L. Breedlove, F. N. Thompson, C. S. Hoveland, J. Ciordia, and
W. E. Townsend. 1985. Utilization and management of endophyte-infested tall fescue: Effects on steer performance and behavior. Proc. 41st South. Pasture Forage Crop Improve. Conf. p 17-10. USDA, ARS, Washington, DC. 30. Thompson, F. N., and J. A. Stuedemann. 1993. Pathophysiology of fescue toxicosis. Agric. Ecosys. Environ. 44:263. 31. Wang, Z. S., and A. L. Goetsch. 1998. Intake and digestion by Holstein steers consuming diets based on litter harvested after different numbers of broiler growing periods or with molasses addition before deep-stacking. J. Anim. Sci. 76:880.
245
Rate Effects on Steer Stocking Performance for Two Methods of Alleviating Fescue Toxicosis1
G. E. AIKEN*,2 and E. L. PIPER† *USDA-ARS, Dale Bumpers Small Farms Research Center, Booneville, AR 72927 and †Animal Science Department, University of Arkansas, Fayetteville, AR 72701
d. Average daily gain for steers fed eastern gamagrass during the compensation phase declined linearly (P<0.05) as Generally, grazing endophyte-infested tall fescue (Festuca arundinace Schreb.) stocking rate increased, but ADG for steers fed tall fescue plus the broiler in the late spring and summer is not litter-corn mixture tended to increase recommended because of the effects of (P<0.10) as stocking rate increased. As a fescue toxicosis on cattle weight gains, result, ADG and live weight gain which can be extreme. For steers (kilograms per hectare) with heavier conditioned to graze tall fescue in the early spring, stocking rate (3, 4, 5, and 6 stocking rates were higher for steers fed tall fescue plus the broiler litter-corn steers/ha) effects were evaluated for two mixture, whereas the responses at a methods designed to avoid poor cattle lighter stocking rate were higher for performance during the late spring and steers fed eastern gamagrass. At the summer (compensation period). The conclusion of the compensation phase in evaluation was conducted in 1997 and 1998, steers fed tall fescue plus the 1998. During the compensation phase, broiler litter-corn mixture had lower one replicate of each stocking rate was (P<0.05) serum prolactin levels, and a randomly assigned to 1-ha pastures of eastern gamagrass (Tripsacum dactyloides higher (P<0.05) proportion of steers fed tall fescue had rough hair coats compared L.), and the other replicate of each stocking rate remained on tall fescue; the with those fed eastern gamagrass. Results of this study show that, for steers steers were fed a 1:1 mixture of broiler litter and corn at 2.27 kg as fed/steer per grazing tall fescue pastures, either eastern gamagrass or supplementation with a broiler litter-corn mixture can provide acceptable performance, but responses are affected by grazing pressure. Symptoms of fescue toxicosis can 1 Names are necessary to report factually on still occur, however.
Abstract
available data; however, the USDA does not guarantee or warrant the standard of the prod- (Key Words: Cattle, Animal Gain, uct, and the use of the name by the USDA Fescue Toxicosis.) implies no approval of the product to the exclusion of others that may also be suitable. 2To
Introduction
Reviewed by K. P. Coffey and A. D. Howes.
Tall fescue is a cool-season perennial grass that is widely adapted and
whom correspondence should be addressed: [email protected]
can persist under poor management. The grass has not had widespread popularity because cattle grazing tall fescue can exhibit symptoms of elevated body temperature, retainment of rough hair coats, and poor growth (17, 24, 29, 30). These symptoms, collectively referred to as fescue toxicosis, are associated with the consumption of toxic alkaloids that are produced by the fungal endophyte (4) Neotyphodium coenophialum (11). Fescue toxicosis is most severe and consequential to calf weight gains at the onset of high ambient temperatures and humidity in the late spring and summer (26, 28, 30). Poor growth and market value of feeder calves exhibiting fescue toxicosis have prevented the wide use of tall fescue for stocker production (16). Problems associated with grazing feeder calves on tall fescue could be reduced or possibly alleviated if the toxins in the diet were diluted by feeding hay or concentrate feeds (2, 5) or if cattle were moved to a warmseason perennial grass pasture during the warm season (9). Steers switched to endophyte-free tall fescue from endophyte-infested tall fescue have increased DMI and exhibited compensatory weight gains (27, 28, 30). Aiken et al. (2) found that steers grazing infested tall fescue and fed a mixture of broiler litter and ground
246
Aiken and Piper
eastern gamagrass were the same for 1997 and 1998 to assess effects of summer grazing treatments on tall fescue pastures. Steers grazing tall Item 1997 1998 fescue during the compensation phase were fed a 1:1 (as fed) mixture N, % 1.8 3.2 of broiler litter and ground corn at a P, % 0.8 1.1 rate of 2.27 kg (as fed)/steer per d K, % 1.4 1.9 (Table 1). This quantity of the Ca, % 1.2 1.8 broiler litter-corn mixture correMg, % 0.4 0.4 sponded to initial consumptions of S, % 0.3 0.4 0.8 and 0.9% BW, respectively, in Fe, mg/kg 6051 51 Mn, mg/kg 601 431 1997 and 1998. The broiler litters fed Zn, mg/kg 302 347 in each of the 2 yr were collected Cu, mg/kg 339 484 from the same broiler house. There was considerable variation in compoaA mineral and vitamin supplement was offered for ad libitum intake to the steers sition (Table 1); however, the litter on tall fescue plus the broiler litter-corn mixture and steers on eastern gamagrass fed in 1998 was collected following treatments that contained Ca (min. 12.0%, max 14.0%), P (min. 12.0%), Na (min. six batches of birds, and the litter fed 4.6%, max. 5.9%), Mg (max. 1.25%), K (min 1.25), Cu (min. 21 ppm), Se (min. 18 in 1997 was collected following only ppm), Zn (min. 300 ppm), vitamin A (441,000 IU/kg), vitamin D3 (99,225 IU/kg), three batches of birds. Feed value of and vitamin E (33 IU/kg). litter is influenced by the number of batches preceding litter harvest (23, 31). Litter in each year was deepstacked, following procedures that corn (1:1; as fed) for ad libitum were recommended by Ruffin and intake had similar ADG to those McCaskey (23) for composting broiler The grazing study was conducted grazing non-infested tall fescue with litter. Samples of the feed mixture in 1997 and 1998 near Booneville (35° were analyzed for minerals using a no supplement. Goetsch (12) reported a twofold increase in ADG for 5' N; 94° 0' W) in northwest ArkanSpectro Model D ICP (Spectro Anasas. The experimental site was on a calves fed infested tall fescue when lytical Instruments, Fitchburg, MA). Leadvale silt loam (fine-silty, siliceous, A mineral-vitamin supplement was ground corn was also fed at 0.75% thermic Typic Fragiudult) soil. Two BW. Broiler litter in a mixture with offered for ad libitum intake in each replicates of four stocking rates (3, 4, pasture to provide trace minerals corn has potential use as low-cost feedstuff (2, 10), particularly in areas 5, and 6 steers/ha) were assigned to (Table 1). eight 1.0-ha pastures of endophytewith extensive poultry production. The steers were implanted with Aiken et al. (2) showed that a broiler infested Kentucky-31 tall fescue in a Synovex-S® (Fort Dodge Animal litter-corn mixture could provide cost- completely randomized design. Health, Fort Dodge, IA) and dewThirty-six yearling steers (25 to 50% effective increases in ADG for steers ormed with ivermectin® (Merck, Inc., Brahman) were randomly assigned to Whitehouse Station, NJ) when initial fed endophyte-infested tall fescue when the corn cost is below $150.00/ stocking rates and pastures in each weights were taken for the conditionyear. The steers grazed the tall fescue ing phase; then, steers were detonne. A grazing study was conducted with the objective of compar- pastures for 6 d to ensure gut fill with wormed again with ivermectin® tall fescue prior to weighing ing stocking rate effects on growth during the compensation phase at 28 unshrunk at the initiation of a performance of steers that were d of grazing. The compensation conditioned to infested tall fescue in conditioning phase. The conditionphase was initiated on May 27, 1997 ing phase was initiated on March 20, (68th d of the conditioning phase) early spring and then, in late spring 1997 (initial steer weight = 276 kg; SE and on June 4, 1998 (56th d of the and summer, were either fed daily a 1:1 (as fed) broiler litter-corn mixture = 18) and on April 9, 1998 (initial conditioning phase). Duration of steer weight = 257 kg; SE = 16). or were moved to pastures of eastern the compensation phase was 76 d in A compensation phase followed gamagrass. Eastern gamagrass is a 1997 and 77 d in 1998. Two meathe conditioning phase by randomly surements were taken at the concluwarm-season perennial grass that is assigning one replicate of each native to most of the eastern U.S. sion of the compensation phase in stocking rate to four 1.0-ha pastures (14) and has potential for high 1998 (August 20) as determinants of of ‘Pete’ eastern gamagrass. Stocking fescue toxicosis. Serum prolactin was productivity (1, 3) and moderate rate assignments to tall fescue and nutritive value (1, 15). measured at the start and conclusion
TABLE 1. Nutrient composition of the broiler litter and ground corn mixtures (DM basis)a.
Materials and Methods
Recovery from Fescue Toxicosis
of the compensation period as a marker for fescue toxicosis (18). Blood samples were collected from the caudal vein at the base of the tail, and serum was obtained from centrifugation and then frozen. The serum was subsequently assayed for prolactin by a double antibody immunoassay (13). Second, hair coat condition of individual steers was rated and recorded as being either sleek, rough, or transitional (i.e., some roughness of hair coat over the rump and shoulder regions). Tall fescue pastures were fertilized on March 7, 1997 with N (67 kg/ha) and then on September 17 with N (84 kg/ha), P (36 kg/ha), and K (69 kg/ ha) and were fertilized on April 1, 1998 with N (84 kg/ha). Eastern gamagrass pastures were fertilized on May 7, 1997 with N (112 kg/ha), P (47 kg/ha), and K (93 kg/ha) and were fertilized on April 15, 1998 with N (112 kg/ha). The tall fescue pastures were mown in early September 1997 to remove accumulated herbage and to provide equal pasture heights at the onset of the fall and spring growth periods. Herbage mass for tall fescue was monitored during the study following procedures described by Bransby et al. (8). Disk meter height was recorded for 50 random locations in each pasture at 14-d intervals. Herbage was also clipped to ground level beneath the disk for two locations within each pasture at 28-d intervals. These samples were dried at 60° C in a forced-air oven for 48 h and weighed for calculation of regression equations that regressed DM per unit of land area over disk meter height. Herbage mass for eastern gamagrass was also measured at 14-d intervals by mowing a 0.9-m ´ 6.1-m area with a Jeri® mower (Year-A-Round CAB Corp., Mankato, MN) at three locations in each pasture. Wet herbage from the harvest strip was weighed and subsampled. Subsamples were dried at 60° C for 48 h in a forced-air oven to calculate herbage mass (kilograms of DM per hectare) as an average of the three locations within each pasture.
247
Figure 1. Relationships between stocking rate (SR) and herbage mass (HM) for steers on tall fescue during the conditioning (A) and compensation (B) phases and for steers on eastern gamagrass during the compensation phase (B).
Average daily gain and live weight gain per hectare (kilograms per hectare) were calculated for each phase and analyzed by examining year and treatment as dummy variables and evaluating stocking rate as a regression variable with deviations from the regression line as the error term (7, 21). The PROC MIXED procedure (20) was used on serum prolactin concentrations of indi-
vidual animals to analyze method and time effects during the compensation phase in 1998. Percentage rough hair coat conditions were analyzed using the Chi Square test (25) to determine association between this hair coat score with either of the two treatments imposed during the compensation phase. Herbage mass data for tall fescue and eastern gamagrass were analyzed separately
248
for stocking rate effects because the data were collected using different methods for the two grasses.
Aiken and Piper
gamagrass mass with increased stocking rate. Steer Performance. Steer ADG during the conditioning phase was relatively high in both 1997 (overall ADG = 0.99 kg/d; SE = 0.1) and 1998 Herbage Mass. Mean herbage (overall ADG = 0.59; SE = 0.06), but a mass (kilograms of DM per hectare) higher (P<0.01) y-intercept for 1997 during the conditioning phase than for 1998 indicated a trend of declined linearly (P<0.05) as stocking higher ADG for that year. The rate increased; the rate of decline was conditioning phase in 1998 was similar (P=0.41) across years (Figure initiated and terminated later than 1A). The y-intercept was higher in 1997 and, therefore, encountered (P<0.01) for 1998 than for 1997, higher ambient temperatures [average indicating that there was a trend for = 27° C (80° F)] than did the conditall fescue mass to be higher in 1998. tioning phase in 1997 [average = 23° This probably was due to the higher C (73° F)]. Therefore, although there N rates that were applied to the tall was greater herbage mass in 1998, fescue pastures in 1998. higher temperatures for that year For the compensation period, likely exacerbated the effect that stocking rate and year effects intertoxicosis had on steer performance. acted (P<0.05) to affect tall fescue Steer ADG was not affected by mass (Figure 1B). The linear decline stocking rate (P=0.82) in either year. in herbage mass with increased Although herbage mass was lower stocking was steeper (P<0.05) for 1997 with heavier stocking, it apparently than for 1998. Steep declines in tall was high enough with these stocking fescue mass with heavier stocking was rates to not limit steer weight gain. anticipated for this period because Unpublished grazing research on growth of the cool-season perennial endophyte-infested tall fescue has grass is typically minimal during the shown weak responses of ADG to hot and humid summer months. stocking rate (D. I. Bransby, Auburn Again, higher soil fertility in 1998 University, Agronomy and Soils might have stimulated some grass Department, Auburn, AL 36849, growth, especially during periods personal communication). Tall when there was adequate soil moisfescue tissues differ in ergovaline (a ture. The tall fescue pastures that toxic alkaloid) concentrations. The were grazed in the summer were not ranking order from highest to lowest visually observed to deteriorate (i.e., is seedheads, stems and sheaths, and weed encroachment), which indileaf blades (22). Belesky and Hill (6) cated that feeding the broiler litterreported alkaloid concentrations of 1 corn mixture at the quantities offered to 5 µg/g DM for two genotypes of resulted in forage consumptions low infested tall fescue and further enough to not severely stress the tall showed leaf sheath tissue to contain fescue. about twice the alkaloid concentraEffects of stocking rate (P=0.26), tion as did leaf blade tissue. High year (P=0.38), or their interaction concentrations of seedhead, stem, (P=0.35) were not detected on herband sheath tissues in lightly stocked age mass of eastern gamagrass. Wide herbage may result in higher conplant spacings and uneven grazing of sumption of alkaloids. Frequent eastern gamagrass made it difficult to grazing promotes leaf blade growth, obtain the precise measurement which can result in lower alkaloid needed to determine treatment effects concentrations in the overall herbage (1). Removing the stocking rate by (6); however, under this condition, year interaction from the statistical animal performance can be limited model provided results that indicated by restricted intake because of low a trend (P<0.10) of reduced eastern herbage mass.
Results and Discussion
High steer performance observed during the conditioning phase might have been related to cooler temperatures as well as lower concentration of ergovaline in the forage grazed in April compared with warmer temperature conditions and higher ergovaline concentrations in the forage grazed in June (22). At the end of the conditioning phase, a high proportion of the steers were visually observed to retain rough hair coats. At the conclusion of the conditioning phase, serum prolactin levels of these steers were approximately seven times lower than those taken from the same steers following 28 d (July 2) on the two treatments during the compensation phase. Normally, steers on non-toxic diets bled on similar dates have similar prolactin levels (19). These data indicate that, at the end of the conditioning phase, the steers were demonstrating several toxicosis symptoms. Average daily gain during the compensation phase in both years responded similarly (P=0.19) to stocking rate; however, the y-intercepts indicated that there was a tendency for higher (P<0.10) ADG in 1997 when herbage masses were generally lower. There was a stocking rate by method interaction (P<0.05) on steer ADG during the compensation phase (Figure 2A). Steer ADG on eastern gamagrass showed a typical linear decline (P<0.05) as stocking rate increased. Aiken (1) did not observe a stocking rate effect on ADG following 84 d of grazing eastern gamagrass, but the steers were not subjected to carry-over effects from grazing infested tall fescue in the spring. Aiken (1) further reported an ADG of 0.81 kg/ d, which is within the range of ADG measured in the present study. Thus, in the present study, performance of steers fed eastern gamagrass apparently was not adversely affected by grazing infested tall fescue in the spring. There was a trend (P<0.10) for ADG to increase as stocking rate increased for steers fed tall fescue plus
Recovery from Fescue Toxicosis
Figure 2. Relationships between stocking rate (SR) and ADG (A) and between SR and liveweight gain per hectare (B) for steers on tall fescue plus the broiler litter-corn mixture and for steers on eastern gamagrass during the compensation phase.
a broiler litter-corn mixture; this is atypical for results of most stocking rate experiments (7, 21). As previously discussed, there might have been reduced concentrations of alkaloids in the diet as stocking rate increased; thus, combined with the broiler litter-corn mixture, there could have been a considerable boost in diet quality. It should be men-
tioned, however, that heavier stocking rates than those used in this study would likely have resulted in low enough herbage masses to limit steer performance. Trends for the two regression lines indicated that ADG was higher for steers fed eastern gamagrass at lighter stocking rates and that ADG was higher for steers fed tall fescue plus the broiler litter-
249
corn mixture at heavier stocking rates. There were linear increases in live weight gain per hectare as stocking rate increased during the compensation phase, but the responses to stocking rate differed (P<0.05) between steers fed eastern gamagrass and those fed tall fescue plus the broiler litter-corn mixture (Figure 2B). The slope of the regression line was steeper (P<0.05) for steers fed tall fescue plus the broiler litter-corn mixture than for steers fed eastern gamagrass. Similar to ADG, trends in the regression lines indicate that live weight gain per hectare was favored by eastern gamagrass with lighter stocking rates but was favored by tall fescue plus the broiler littercorn mixture with heavier stocking rates. Symptoms of Toxicosis. As previously discussed, serum prolactin concentrations at the initiation of the compensation phase in 1998 were low. The grazing of infested tall fescue by cattle has been shown to suppress serum prolactin (1, 19). Reduced serum prolactin is, therefore, a symptom of fescue toxicosis; however, prolactin has not been directly related to the incidence of fescue toxicosis (19). Interactions of other hormones with the endotoxins have been implicated as the contributing factors causing toxicosis (29, 30), which suggests that reductions in serum prolactin in cattle exhibiting fescue toxicosis may be in response to changes in concentrations of other hormones that are inducing fescue toxicosis. Serum prolactin levels in steers under the two compensation methods increased at different rates (P<0.01) from baseline measurements taken initially for the compensation phase (Figure 3). Levels for steers grazing eastern gamagrass were higher than those for steers grazing tall fescue plus the broiler litter-corn mixture on July 2 (P<0.001) and August 20 (P<0.05). Among animal variation for the July 31 sample date was too high to detect differences
250
Aiken and Piper
Implications Results of the study indicate that weight gains of feeder steers grazing tall fescue in the late spring and summer can be improved if the steers are either moved to eastern gamagrass or fed daily a 1:1 broiler litter-corn supplement in a quantity of at least 0.8% BW (as fed). The extent of the enhancement of weight gains cannot be determined because a control treatment, tall fescue only, was not examined during the compensation phase because it was deemed too detrimental to the animals and pastures and because such effects have already been well documented. It can be assumed, however, that the combined effects of the endophyte and low herbage masses for this type of treatment would have had detrimental effects on steer performance. Trends in the regression lines for ADG and live weight gain per hectare indicate that fescue plus the broiler litter-corn mixture provided higher steer performance with moderate to heavy stocking rates and that eastern gamagrass provided higher performance with lighter stocking rates. Figure 3. Relationships between sample date and serum prolactin concentrations during the The two methods of reducing the compensation phase for steers on tall fescue plus the broiler litter-corn mixture and for steers adverse effects of fescue toxicosis in on eastern gamagrass. Baseline measurements were taken on June 4 at the initiation of the the late spring and summer provide phase. Standard error bars and P values are provided for the difference between the two options for extending the time that treatments. The measurements were taken in 1998. cattle can remain on pasture for extra backgrounding for the feedlot or to wait for suitable market conditions. One problem, however, is that a was probably a reflection of the trend certain portion of calves, particularly (P=0.24). Therefore, movement of toward a higher percentage of steers those that remain on tall fescue and steers from tall fescue to eastern with rough hair coats when those are fed the broiler litter-corn mixture, gamagrass was more effective in steers were grazing tall fescue and fed can still exhibit symptoms of toxicoraising serum prolactin levels than it the broiler litter-corn mixture comsis and, therefore, have reduced was in allowing steers to remain on pared with steers grazing the eastern market values. Therefore, fescue tall fescue while feeding the broiler gamagrass. Aiken et al. (2) reported toxicosis cannot be completely litter-corn mixture. There was no avoided for cattle fed a broiler litterstocking rate effect (P=0.24) on serum that approximately 38% of steers grazing infested tall fescue and fed corn mixture and grazing tall fescue prolactin levels for either of the two the broiler litter-corn mixture for ad in the summer. treatments. libitum intake had rough hair coats. Distributions of hair coat ratings It was concluded that some cattle at the conclusion of the compensamay be too sensitive to the alkaloids tion phase in 1998 (Figure 4) were The authors express appreciation for dilution of alkaloids in the diet to different (P<0.05) between steers eliminate fescue toxicosis completely. to Sam Tabler of USDA-ARS for grazing tall fescue plus the broiler providing advice and technical litter-corn mixture and steers grazing Results of the present study support support to the project and to Tamara this conclusion. eastern gamagrass. This difference
Acknowledgments
251
Recovery from Fescue Toxicosis
7. Bransby, D. I., B. E. Conrad, H. M. Dicks, and J. W. Drane. 1988. Justification for grazing intensity experiments: Analyzing and interpreting grazing data. J. Range Mange. 41:274. 8. Bransby, D. I., A. G. Matches, and G. F. Krause. 1977. Disk meter for rapid estimation of herbage yield in grazing trials. Agron. J. 69:393. 9. Brown, M. A., A. H. Brown, Jr., W. G. Jackson, and J. R. Miesner. 1997. Preweaning performance of Beefmaster- and Brahmansired calves from Angus and Brahman cows on three forage systems. Prof. Anim. Sci. 13:90. 10. Fontenot, J. P., and K. E. Webb, Jr. 1975. Health aspects of recycling animal wastes by feeding. J. Anim. Sci. 40:1267. 11. Glenn, A. E., C. W. Bacon, R. Price, and R. T. Hanlin. 1996. Molecular phylogeny of Acremonium and its taxonomic implications. Mycologia 88:369. 12. Goetsch, A. L. 1989. Effects of supplementation on feed intake, digestion and performance by cattle consuming endophyteinfected tall fescue. In Proc. Ark. Fescue Toxicosis Conf. C. P. West (Ed.). p. 17. Ark. Exp. Stn. Spec. Rep. 140. Fayetteville, AR. 13. Henson, M. C., E. L. Piper, and L. B. Daniels. 1987. Effects of induced fescue toxicosis on plasma tissue catecholamine concentrations in sheep. Domest. Anim. Endocrinol. 4:7. 14. Hitchcock, A. S. 1951. Manual of the grasses of the United States (2nd Ed.). USDA Misc. Publ. No. 200., Washington DC.
Figure 4. Percentages rough, sleek, and transitional hair coats at the conclusion of the compensation period in 1998 for steers on tall fescue plus the broiler litter-corn mixture and for steers on eastern gamagrass .
Denard of the University of Arkansas for conducting laboratory analyses.
2. Aiken, G. E., D. M. Ball, E. L. Piper, and C. P. West. 1998. Performance of steers fed a broiler litter-corn mixture on endophyteinfested and non-infested tall fescue. Prof. Anim. Sci. 14:51. 3. Anderson, R. C. 1985. Aspects of germination ecology and biomass production of eastern gamagrass (Tripsacum dactyloides L.). Bot. Gaz. 146:353.
Literature Cited 1. Aiken, G. E. 1997. Temporal effects on steer performance and nutritive values for eastern gamagrass grazed continuously for different durations. J. Anim. Sci. 75:803.
4. Bacon, C. W., J. K. Porter, J. D. Robbins, and E. S. Luttrell. 1977. Epichloe typhina from tall fescue grasses. Appl. Environ. Microbiol. 35:576. 5. Ball, D. M. 1984. An overview of fescue toxicity research. Auburn Vet. 39:66. 6. Belesky, D. P., and N. S. Hill. 1997. Defoliation and leaf age influence on ergot alkaloids in tall fescue. Ann. Bot. 79:259.
15. Horner, J. L., L. J. Bush, G. D. Adams, and C. M. Taliaferro. 1985. Comparative nutritional value of eastern gamagrass and alfalfa hay for dairy cows. J. Dairy Sci. 68:2615. 16. Hoveland, C. S. 1993. Importance and economic significance of the Acremonium endophytes to performance of animals and grass plant. Agric. Ecosys. Environ. 44:3. 17. Hoveland, C. S., S. P. Schmidt, C. C. King, Jr., J. W. Odom, E. M. Clark, J. A. McGuire, L. A. Smith, H. W. Grimes, and J. L. Holliman. 1983. Steer performance and association of Acremonium coenphialum fungal endophyte on tall fescue pasture. Agron. J. 75:821. 18. Jacobson, D. R., W. M. Miller, and D. M. Seath. 1963. Nature of fescue toxicity and progress toward identification of the toxic entity. J. Dairy Sci. 46:416. 19. Krag, H., and D. Schams. 1974. Prolactin release in cattle. J. Reprod. Fertil. 39:463. 20. Littel, R. C., G. A. Milliken, W. W. Stroup, and R. D. Wolfinger. 1996. SAS System for Mixed Models. SAS Institute, Inc., Cary, NC. 21. Riewe, M. E. 1961. Use of the relationship of stocking rate to gain of cattle in an experimental design for grazing trials. Agron. J. 53:309.
252
22. Rottinghaus, G. E., G. B. Garner, C. N. Cornell, and J. L. Ellis. 1991. HPLC method for quantitating ergovaline in endophyteinfested tall fescue: Seasonal variation of ergovaline levels of stems with leaf sheaths, leaf blades, and seed heads. J. Agric. Food Chem. 39:112. 23. Ruffin, B. G., and T. A. McCaskey. 1990. Broiler litter can serve as a feed ingredient for beef cattle. Feedstuffs 62:13. 24. Schmidt, S. P., and T. G. Osborn. 1993. Effects of endophyte-infected tall fescue on animal performance. Agric. Ecosys. Environ. 44:233. 25. Steel, R.G.D., and J. H. Torrie. 1980. Principles and Procedures of Statistics: A Biometrical Approach. McGraw-Hill, New York, NY.
Aiken and Piper
26. Strickland, J. R., J. W. Oliver, and D. L. Cross. 1993. Fescue toxicosis and its impact on animal performance. Vet. Human Toxicol. 35:454. 27. Stuedemann, J. A., D. L. Breedlove, K. R. Pond, D. P. Belesky, L. P. Tate, Jr., F. N. Thompson, and S. R. Wilkinson. 1989. Effect of endophyte (Acremonium coenphialum) infection of tall fescue and paddock exchange on intake and performance of grazing steers. In Proc 16th Int. Grassl. Congr. p 1243-1244. Nice, Fr. 28. Stuedemann, J. A., and C. S. Hoveland. 1988. Fescue endophyte: History and impact on animal agriculture. J. Prod. Agric. 1:39. 29. Stuedemann, J. A., S. R. Wilkinson, D. P. Belesky, O. J. Devine, D. L. Breedlove, F. N. Thompson, C. S. Hoveland, J. Ciordia, and
W. E. Townsend. 1985. Utilization and management of endophyte-infested tall fescue: Effects on steer performance and behavior. Proc. 41st South. Pasture Forage Crop Improve. Conf. p 17-10. USDA, ARS, Washington, DC. 30. Thompson, F. N., and J. A. Stuedemann. 1993. Pathophysiology of fescue toxicosis. Agric. Ecosys. Environ. 44:263. 31. Wang, Z. S., and A. L. Goetsch. 1998. Intake and digestion by Holstein steers consuming diets based on litter harvested after different numbers of broiler growing periods or with molasses addition before deep-stacking. J. Anim. Sci. 76:880.