Intake and digestion of 'Jesup' tall fescue hays with a novel fungal endophyte, without an endophyte, or with a wild-type endophyte.
The persistence and long-term survival of tall fescue in the transition zone has been associated with the presence of the endophyte Neotyphodium coenophialurn (Morgan-Jones & Gams.) Glenn, Bacon & Hanlin comb. nov. (Bacon et al., 1986; Bouton et al., 1993, 2002: Bacon, 1995; Porter, 1995). The same endophyte, however, has been associated with tall fescue toxicosis (Hill et al., 1994) expressed, in part, as reductions in animal weight gains (Stuedemann and Hoveland, 1988; Fribourg et al., 1991; Schmidt and Osborn, 1993). Reduced gains have been largely attributed to ingestion of ergot alkaloids produced by the endophyte (Aldrich et al., 1993a, 1993b; Rice et al., 1997; Burke et al., 2001a, 2001b). Reduced animal performance is accompanied by either reduced daily dry matter intake (Emile et al., 2000) or dry matter digestion (Hannah et al., 1990; Fiorito et al., 1991) or both (Aldrich et al., 1993a; Strickland et al., 1993).
This lack of consistency is likely associated with the degree of stress on the animal and related to ambient temperature, concentration and type of ergot alkaloids present in the plant, the quantity of alkaloids in the animal's diet, and the physiology of the individual animal. Clinical signs of fescue toxicosis are often more severe when animals are consuming N. coenophialum-infected tall rescue while ambient temperatures approach or exceed 31[degrees]C (Bacon et al., 1986). Under such conditions, a 10% unit increase in endophyte level has been associated with a 0.45 kg reduction in daily performance (Stuedemann and Hoveland, 1988; Fribourg et al., 1991).
Recently, 'Jesup' tall rescue was developed in Georgia as an endophyte-free cultivar and released based on improved stand persistence for the Southern Coastal Plain (Bouton et al., 1997), and high animal performance in the Southern Piedmont (Hoveland et al., 1997). Further, a novel (nontoxic) endophyte of N. coenophialum was incorporated into Jesup providing enhanced summer survival without reducing animal performance (Bouton et al., 2002). Jesup tall fescue is presently being marketed under the trademark of MaxQ tall rescue (Pennington Seed, Madison, GA; Bouton et al., 2002) and may offer improved persistence and animal performance in grazing systems across the Mid-Atlantic Region.
In the Southern Piedmont, hay is typically managed in concert with utilization by grazing. The hay harvests typically occur from late spring into early summer. Hay is generally fed on an as-needed basis during late fall and winter. Consequently, stand longevity and desirable hay quality are essential characteristics for an improved cultivar. Although the novel endophyte was introduced into Jesup (MaxQ) tall rescue to aid stand persistence, it is unclear how it may affect dry matter intake and digestion by animals when it is fed as hay. The objective of this study was to determine the dry matter intake and digestion of Jesup hay when containing the MaxQ endophyte compared with Jesup that is endophyte free and with Jesup containing a wild-type endophyte utilizing separate experiments with goats, sheep, and cattle. The digestible intake of dry matter, crude protein, and fiber fractions was also tested for variation within each of the three-animal species experiments.
MATERIALS AND METHODS
The experimental hays were harvested from three separate well-established stands of Jesup tall fescue grown on a Cecil clay loam (fine, kaolinitic, thermic Typic Kandiudults) at the Reedy Creek Road Field Laboratory, Raleigh, NC. One stand consisted of Jesup free of endophyte, the second of Jesup with the MaxQ endophyte presumably without ergot-like alkaloid production, and the third stand was Jesup with a wild-type endophyte presumably capable of producing ergot-like alkaloids. All three stands representing endophyte status were cut for evaluation at each harvest date.
All stands of tall fescue were flail chopped to an 8-cm stubble in late February to remove winter growth. The areas were initially treated with lime at 1680 kg [ha.sup.-1], and then P and K were applied according to soil test. Ammonium nitrate was top-dressed in early March and again after the removal of the initial growth at 78 kg N [ha.sup.-1]. Initial growth was cut in the late vegetative to flag-leaf stage on 20 April, and the vegetative regrowth was cut 29 June 2001 when canopy height reached approximately 30 cm. Maturity stage was similar among endophyte status within each harvest.
All forage was cut with a mower conditioner set at a 10-cm height. After cutting, and again each day, the forage was redistributed with a tedder to aid drying. The forage was then baled with a conventional square baler and stored on wooden pallets in a metal building until fed. Just before feeding, the hays were passed through a hydraulic bale processor (Van Dale 5600, J. Starr Industries, Fort Atkinson, WI) with stationary knives spaced 10 cm apart. This procedure cut the hay into length of 7 to 13 cm to aid utilization by the animals while avoiding leaf loss.
Six Boer goats and Katahdin sheep were selected for uniformity from the University herds. The six Boer goats used in Exp. 1 had initial weights ranging from 27 to 31 kg, and the six Katahdin sheep used in Exp. 2 had initial weights ranging from 32 to 37 kg. Both goats and sheep were held in digestion crates in an enclosed, but well-ventilated metabolism unit with moderate temperature control (ambient air maintained > 13[degrees]C and < 24[degrees]C) with free access to trace mineralized salt and water. When animals were placed in crates, they were fitted with a collection harness for future fecal collections. After initial conditioning to the crates and harness and following standardization, each animal was randomly assigned to one of the six hay treatments. At initiation of the digestion phase, canvas bags with plastic inserts were positioned on the collection harness for total fecal collection. The bags were emptied and feces processed daily.
Fifteen Angus steers weighing from 228 to 322 kg were used in Exp. 3. The steers were confined to a covered, outdoor, raised platform equipped with electronic gates (American Calan Inc., Northwood, NH) as previously described (Burns et al., 1994) during the intake phase of the study. Each steer was keyed electronically to allow access to only one feeder, but animals could lounge together and had free access to mineralized salt and water. After conditioning to the gates, and following standardization, animals were blocked by weight and each animal randomly assigned to one of the three forage treatments within each block. For the digestion phase (immediately following each period of the intake phase), the steers were moved from the intake area into the adjacent metabolism section with moderate temperature control (>13[degrees]C and <29[degrees]C) and into digestion crates with free access to mineralized salt and water. Feces were collected on plastic sheets placed on the floor immediately in back of the crates and processed daily.
Intake and Digestion Trials
The three experimental forages harvested as initial growth and again as regrowth (six hays) were evaluated together in experiments using wether goats (Exp. 1) and sheep (Exp. 2). The goats and sheep made up separate experiments conducted in six by six Latin square designs (three experimental forages and two harvest dates). The three hays from the 29 June regrowth harvest were also evaluated by steers (Exp. 3) using a randomized complete block design (blocked by animal weight) with five steers per treatment.
Animals in each experiment were standardized for 14 d on a bulk source of endophyte-free Jesup hay. Each experimental period for goats (Exp. 1) and sheep (Exp. 2) consisted of 21 d, with the first 5 d allowed for adjustment and with total fecal collection the last 5 d. In the case of steers, the experimental period consisted of a 21-d intake phase followed by a 12-d digestion phase (7-d adjustment and 5-d collections).
In both the intake and digestion phases, the forage treatments were fed twice daily allowing a 15% excess. Adjustments were based on the intake of the previous day. Calculation of ad libitum dry matter intake was based on the last 16 d for goats and sheep and the last 14 d for steers. A daily sample of the offered forage was obtained for each animal and contributed to a composite sample on a weekly basis in the intake phase and for the 5-d collection period in the digestion phase. Orts were also taken twice daily and saved for each animal and a composite sample saved for each week in the intake phase and for the 5-d collection period in the digestion phase. The weekly composite samples of the offered forage and orts were further composited for the intake period. All samples were thoroughly mixed, subsampled, oven dried (55[degrees]C) to a constant weight (generally 48 h), and used for dry matter determination and stored for grinding. During the digestion phase, feces were collected and weighed for each of five consecutive 24-h periods. Feces were thoroughly mixed daily and a proportion (5% of total) of the fresh weight was placed in a freezer (-14[degrees]C). Following the 5-d collection, the composite frozen samples were oven dried (55[degrees]C) to constant weight (generally 48 h) for dry matter determination, and stored for grinding.
All feed, ort, and fecal samples from the intake and digestion phases of each experiment were ground in a Wiley mill to pass a 1-mm screen, scanned in a near-infrared reflectance spectrophotometer (NIRS), and the H statistic (0.6) used to identify select samples by spectra for laboratory analyses to develop NIRS prediction equations for all samples.
In vitro true dry matter disappearance (IVTDMD) was determined by 48 h fermentation in a batch fermentation vessel (Ankom Technology Corp., Fairport, NY) with artificial saliva and rumen inoculum according to Burns and Cope (1974). Ruminal inoculum was obtained from a mature Hereford steer fed a mixed alfalfa (Medicago sativa L.) and orchardgrass (Dactylis glomerata L.) hay. Total N was determined by auto-analyzer (Association of Official Analytical Chemists, 1990), and crude protein (CP) was estimated as 6.25 times total N. Fiber fractions consisting of neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose, and sulfuric acid lignin were estimated in a batch processor (Ankom Technology Corp., Fairport, NY) using reagents according to Van Soest and Robertson (1980). Hemicellulose was determined by difference (NDF-ADF). Laboratory values were used to develop NIRS calibration equations from feed and ort samples and separately from fecal samples to predict each sample from the reflectance spectrum (Table 1).
Endophyte infection was verified by randomly cutting basal tillers from fescue in each hay field (150 tillers), placing them in plastic bags (Randell-Schadel, 1995) on ice and immediately delivering them to the Tall Fescue Endophyte Testing Laboratory, N.C. Dep. of Agric., Raleigh, N.C. Endophyte infestation averaged 94.0, 95.3, and 5.3% for the wild-type, MaxQ, and the endophyte-free fields, respectively. Differences in total ergot alkaloid concentrations of the fed hays were verified using the ELISA test (N.S. Hill, University of Georgia, Athens, GA) according to Adcock et al. (1997). The wild-type, MaxQ, and the endophyte-free hays averaged 221, 103, and 110 [micro]g [kg.sup.-1], respectively (minimum significant difference = 33 [micro]g [kg.sup.-1]; CV = 9.8%).
Data from the intake and digestion phases for Exp. 1 and 2 were analyzed as six by six Latin squares using a mixed model. The model included terms for animal, period, endophyte status, and harvest (Steel and Torrie, 1980). Animal and period were random effects and endophyte status and harvest were fixed effects. Data from the intake and digestion phases for Exp. 3 were analyzed as a randomized complete block. The mixed model included a random term for blocks and a fixed term for endophyte status. Means for all variables found significant were separated using the minimum significant difference (MSD) based on the Waller-Duncan k ratio t test. Because of the expected variation in estimates of animal intake and digestion, an a priori decision was made to test these variables with the k ratio set at 50 and to reject the null hypothesis with P [less than or equal to] 0.10. All forage and fecal composition data were tested with the k ratio set at 100 and the null hypothesis was rejected for P [less than or equal to] 0.05.
The hays harvested on 20 April were grown under mild conditions with rainfall above average in March and slightly below average in April (Table 2). The regrowth forage harvested 29 June grew under warmer temperatures with a mean of 23.7[degrees]C in June. Severe moisture stress did not occur during either growth period. All hays were field cured during 3 d without exposure to rain, were preserved without heat damage, and were stored out of direct sunlight.
Neither the goat responses measured nor the composition of the hays showed an endophyte status by harvest date interaction. Consequently, only the main effects are reported.
The daily intake of goats fed the MaxQ hay was greater compared with the wild-type hay (2.63 vs. 2.43 kg [100.sup.-1] kg BW; P < 0.10), but similar to the endophyte-free hay (Table 3). The daily intakes of the endophyte-free and wild-type hays were similar. Also, dry matter intake was similar for the two harvest dates.
Apparent digestion for dry matter, CP, and fiber fractions were similar for all three hays (Table 3). The hays harvested in April had greater digestibility for dry matter, CP, and fiber fractions compared with the June-harvested hays.
The daily digestible intake of CP was greater with the MaxQ endophyte than the wild type (Table 4; P < 0.01). Even though the digestible dry matter intake did not have a significant F test (P = 0.12), the MSD (k ratio = 50) is still a valid test and indicated that the MaxQ hay and wild-type hays differed. The daily digestible intake of dry matter, CP, and the fiber fractions was greater for the hays harvested in April than the hays harvested in June.
The composition of the hays differed (P [less than or equal to] 0.05) among endophyte status for IVTDMD, CP, NDF, hemicellulose, and cellulose, but not for ADF or lignin (Table 5). MaxQ and endophyte-free hays were similar according to the calculated MSD values, but the MaxQ and endophyte-free hays differed from the wild type in IVTDMD and CP concentrations. The wild type had greater concentrations of NDF and hemicellulose than the endophyte-free hay, but the wild type was similar to MaxQ. The cellulose concentration of the wild type was greater than the MaxQ, but the difference was only equal to the MSD, and the endophyte-free line was intermediate.
The hays harvested in April had greater concentrations of IVTDMD and CP and lower fiber fractions than hays harvested in June (Table 5). It should be noted that lignin concentrations gave an endophyte status by harvest date interaction (P = 0.02; data not shown). This was the result of greater lignin concentrations for MaxQ and endophyte-free hays harvested in June compared with April (32 vs. 26 g [kg.sup.-1]), while concentrations in the wild-type hay were similar (30 g [kg.sup.-1]).
As noted with goats, none of the sheep responses measured or the composition of the hays showed a significant endophyte by harvest date interaction. Consequently, only the data for the main effects are reported (Table 6). The daily dry matter intake by sheep was not altered by endophyte status. The hays harvested in April, however, were consumed in greater amounts compared with hays harvested in June.
The apparent digestion of dry matter, CP, and fiber fractions of the hays were similar among the endophyte treatments (Table 6). The digestibility of the dry matter and fiber fractions of the hays harvested in April were greater than the hays harvested in June. The digestibility of CE however, was similar between harvest dates.
Within the ANOVA, the digestible daily intakes of dry matter, CP, and fiber fractions were not altered by endophyte status (Table 7). However, the MSD (k ratio = 50) indicated small differences between the daily digestible dry matter and hemicellulose intakes of MaxQ and the wild type. Hays harvested in April had greater daily digestible intakes of dry matter, CP, and fiber fractions compared with hays harvested in June.
The IVTDMD, CP, and fiber fractions were generally similar regardless of endophyte status (Table 8). An exception was that hemicellulose in MaxQ hay was greater than in endophyte-free hay with the wild-type intermediate. In addition, the MSD (k ratio = 100; F test P = 0.07) indicated that the concentration of lignin in the endophyte-free hay was greater than in the wild type or MaxQ. Concentration of IVTDMD and CP were greater in the April-harvested forage; whereas NDF and its fiber constituents were consistently lower.
Only hays from the June harvest were selected for evaluation by cattle. Daily dry matter intake of steers was not altered by endophyte status (Table 6). Furthermore, forages were of similar digestibilities (Table 7) and daily digestible intakes of dry matter, CP, NDF, and constituent fiber fractions.
The composition of the hays differed among endophyte status for IVTDMD (P < 0.01) and CP (P < 0.01) (Table 8). The IVTDMD of the rescue containing the wild-type endophyte was less than the IVTDMD of the MaxQ and endophyte-free hays. The CP concentration of the endophyte-free hay was greater than for wild-type hay but similar to MaxQ. Concentrations of NDF, ADE hemicellulose, cellulose, and lignin were all similar (P ranged from 0.07 to 0.46).
Testing of the infection levels of the tall rescue stands used for hay production showed the wild type was 94.0% infected, MaxQ was 95.3% infected, and the endophyte-free stand was 5.3% infected. Total ergot alkaloid concentrations of the fed hays averaged 221, 103, and 110 [micro]g [kg.sup.-1], respectively. The total ergot alkaloid concentrations in the hays of MaxQ (Jesup + AR 542 endophyte strain, Bouton et al., 2002) and Jesup essentially free of endophyte were of the same magnitude as reported in field trials by Bouton et al. (2002) and Hill et al. (2002). The total ergot alkaloid concentrations of the wild type in this study, although double the concentrations noted in MaxQ and the endophyte-free hays, were about 1/5 of the level reported by Bouton et al. (2002). This difference may, in part, be attributed to a lack of alkaloid stability associated with photolysis, oxidation, and rehydration of the plant tissue (Garner et al., 1993; Porter, 1995). Sun curing of forages, as done in this study, would involve several cycles of drying and rehydration. Recently, Fletcher (2005) reported that ergovaline concentrations in ryegrass (Lolium perenne L.) at harvest did not decline when ensiled, but when stored as hay, the concentration declined and was negligible by 207 d after harvest. Further, Kallenbach et al. (2003) reported a decline in ergovaline concentrations of about 85% between December and March in 'HiMag' tall fescue when managed as a stockpile. Further evaluation is needed to determine the degree to which concentrations of ergot-like alkaloids decline during hay-curing and storage at ambient temperature and humidity.
The use of an April and June harvest in this study provided vastly different environments for the production of the experimental hays. Tall rescue harvested in April, although in a more advanced physiological stage compared with the June regrowth, was greater in nutritive value. This was reflected in greater dry matter intake by sheep and greater dry matter digestion and intake of digestible forage and forage fiber by both sheep and goats, and is attributed to cooler and moist environmental conditions (Table 2; Deinum et al., 1968; Allinson, 1971; Hemken et al., 1981).
Differences among the endophyte treatments varied appreciably. Goats consumed more of the MaxQ hay compared with the hay containing the wild-type endophyte, whereas sheep and cattle consumed all three hays similarly. Differences among animal species are consistent with literature findings (Fiorito et al., 1991; Emile et al., 2000).
Dry matter digestion was similar among hays within each animal trial. Combining dry matter intake and dry matter digestion to give estimates of digestible dry matter intake showed goats and sheep, but not cattle, to have greater digestible dry matter intakes when fed MaxQ hay.
Crude Protein and Fiber Fractions
Digestibility of CP and the fiber fractions were generally similar for endophyte status within each animal species. However, the difference in apparent digestion of MaxQ hay and the wild-type hay was equal to the MSD contributing to differences in digestible CP intake (P < 0.01). In general, the digestible intakes of NDF and its fiber constituents were similar among endophyte status in all three experiments.
The composition data generally supported the animal responses obtained for goats and sheep. The greater dry matter intake obtained with goats fed MaxQ hay is consistent with its observed greater IVTDMD and CP and lower ADF and cellulose concentrations relative to the wild-type hay. In the case of sheep, dry matter intake was similar among endophyte status and consistent with similar IVTDMD, CE and fiber fraction concentrations. The composition data from the steer trial showed IVTDMD was least for the wild-type hay and the wild-type hay also had less CP than the endophyte-free hay. However, these differences were not reflected in steer dry matter intake (P [greater than or equal to] 0.10). In general, estimates of nutritive value from other tall fescue cultivars when compared with and without toxic endophyte have shown little response to the presence of the endophyte (Turner et al., 1990; Collins, 1991; Asay et al., 2002).
The detailed sampling protocol of daily collecting a sample of the feed offered each animal revealed variation in the composition of hay. For example, the differences in composition found among the hays in the goat trial were generally not noted in the sheep trial. Also, the means observed among hays fed from the June harvest to goats and sheep (data not shown) were generally similar for CP, hemicellulose and lignin, but in the steer trial, the statistical differences noted among the same hays occurred for different variables. In the steer trial, differences were found mainly in IVTDMD, CP, and NDF concentrations. These observations demonstrate the importance that should be placed on the daily sampling of feeds offered for accurate estimates of nutritive value of feeds utilized in animal trials. Without an adequate sampling protocol, it would be natural to assume that analyses of a limited number of bale cores from each bulk lot would be representative of the hays to be offered in each of the animal trials.
The results from this study showed that Jesup tall fescue with the MaxQ endophyte gave similar or greater animal responses as Jesup tall rescue when endophyte free. Short-term steer daily performance when steers consumed the June harvested hays averaged 0.98, 1.23, and 0.80 kg for the endophyte free, MaxQ, and wild-type endophyte hays, respectively (SE = [+ or -] 0.17 kg). Although these performance data are short term, they are consistent with observations of dry matter intake, dry matter digestion, and digestible dry matter intake. Steers consuming the MaxQ hay performed well relative to the other two hay treatments, and the presence of the novel endophyte did not negatively influence animal responses. These data indicated that Jesup tall rescue hay with the MaxQ endophyte should provide a suitable source of nutrients when fed during the winter in the mid-Atlantic region (National Research Council, 1996). On the other hand, hay containing the wild-type endophyte generally gave similar responses with sheep and cattle as did MaxQ or endophyte-free hays during these winter feeding trials. In all trials, animals gained weight with the mean weight of goats increasing 8 kg, sheep 11 kg, and steers gains averaged 1 kg [d.sup.-1] as noted above. Because tall fescue stands are utilized both as a pasture and a hay source, the agronomic aspects of forage production warrant special consideration. Improved stand persistence occurs through the presence of endophyte (Arachevaleta et al., 1989); however, ergot-alkaloid producing endophytes can negatively influence animal performance during the grazing season. These latter considerations may be far more important in cultivar selection for use in production systems, than is the influence of the endophyte on nutritive value of harvested forage stored as hay for winter utilization. Further research is warranted to characterize the change in ergot-alkaloids during sun curing and storage under ambient conditions. Also, studies are needed to test hay quality of the novel endophytes in long-term performance trials with ruminants.
Abbreviations: ADE acid detergent fiber; CE crude protein; IVTDMD, in vitro true dry, matter disappearance; MSD, minimum significant difference; NDE neutral detergent fiber.
Adcock, R.A., N.S. Hill, J.H. Bouton, H.R. Boerma, and G.O. Ware. 1997. Symbiont regulation and reducing ergot alkaloid concentration by breeding endophyte-infected tall rescue. J. Chem. Ecol. 23:691-704.
Aldrich, C.G., J.A. Paterson, J.L. Tate, and M.S. Kerley. 1993a. The effect of endophyte--infected tall fescue consumption on diet utilization and thermal regulation in cattle. J. Anim. Sci. 71:164-170.
Aldrich, C.G., M.T. Rhodes, J.L. Miner, M.S. Kerley, and J.A. Paterson. 1993b. The effects of endophyte-infected tall fescue consumption and use of a dopamine antagonist on intake, digestibility, body temperature, and blood constituents in sheep. J. Anim. Sci. 71:158-163.
Allinson, D.W. 1971. Influence of photoperiod and thermoperiod on the IVDMD and cell wall components of tall fescue. Crop Sci. 11: 456-458.
Association of Official Analytical Chemists. 1990. Official methods of analysis. 15th ed. AOAC, Arlington, VA.
Arachevaleta, M., C.W. Bacon, C.S. Hoveland, and D.E. Radcliffe. 1989. Effect of the tall rescue endophyte on plant response to environmental stress. Agron. J. 81:83-90.
Asay, K.H., K.B. Jensen, B.L. Waldron, G. Ham D.A. Johnson, and T.A. Monaco. 2002. Forage quality of tall fescue across an irrigation gradient. Agron. J. 94:1337-1343.
Bacon, C.W. 1995. Toxic endophyte-infected tall fescue and range grasses--Historic perspectives. J. Anim. Sci. 73:861-870.
Bacon, C.W., PC. Lyons, J.K. Porter, and J.D. Robbins. 1986. Ergot toxicity from endophyte- infected grasses: A review. Agron. J. 78: 106-116.
Bouton, J.H., R.R. Duncan, R.N. Gates, C.S. Hoveland, and D.T. Wood. 1997. Registration of 'Jesup' tall fescue. Crop Sci. 37:1011-1102.
Bouton, J.H., R.N. Gates, D.P. Belesky, and M. Owsley. 1993. Yield and persistence of tall fescue in the southeastern coastal plain after removal of its endophyte. Agron. J. 85:52-55.
Bouton, J.H., G.C. Latch, N.S. Hill, C.S. Hoveland, M.A. McCann, R.H. Watson, J.A. Parish, L.L. Hawkins, and EN. Thompson. 2002. Reinfection of tall fescue cultivars with non-ergot alkaloid-producing endophytes. Agron. J. 94:567-574.
Burke, J.M., R.W. Rorie, E.L. Piper, and W.G. Jackson. 2001a. Reproduction responses to grazing endophyte-infected tall fescue. Theriogenology 56:357-369.
Burke, J.M., D.E. Spiers, EN. Kojima, G.A. Perry, B.E. Salfen, S.L. Wood, D.J. Patterson, M.F. Smith, M.C. Lucy, and W.G. Jackson. 2001b. Interaction of endophyte-infected fescue and heat stress on ovarian function in the beef heifer. Biol. Reprod. 65:260-268.
Burns, J.C., and D.S. Chamblee. 1979. Adaptation. p. 9-30. In R.C. Buckner and L.P. Bush (ed.) Tall rescue. Agron. Monogr. 20. ASA, CSSA, and SSSA, Madison, WI.
Burns, J.C., and W.A. Cope. 1974. Nutritive value of crownvetch forage as influenced by structural constituents and phenolic and tannin compounds. Agron. J. 66:195-200.
Burns, J.C., K.R. Pond, and D.S. Fisher. 1994. Measurement of forage intake, p. 494-532. In G.C. Fahey, Jr. et al. (ed.) Forage quality, evaluation and utilization. ASA, CSSA, and SSSA, Madison, WI.
Collins, M. 1991. Nitrogen effects on yield and forage quality of perennial ryegrass and tall fescue. Agron. J. 83:588-595.
Deinum, B.A., J.H. Van Es, and RJ. Van Soest. 1968. Climate, nitrogen and grass. 2. The influence of light intensity, temperature and nitrogen on vivo digestibilities of grass and the prediction of these effects from some chemical procedures. Neth. J. Agric. Sci. 16:217-223.
Emile, J.C., S. Bony, and M. Ghesquiere. 2000. Influence of consumption of endophyte infected tall rescue hay on performance of heifers and lambs. J. Anim. Sci. 78:358-364.
Fiorito, I.M., L.D. Bunting, G.M. Davenport, and J.A. Boling. 1991. Metabolic and endocrine responses of lambs fed Acremonium coenophialum-infected or noninfected tall fescue hay at equivalent nutrient intake. J. Anim. Sci. 69:2108-2114.
Fletcher, L.R. 2005. Managing ryegrass-endophyte toxicosis, p. 229-241. In C.A. Roberts et al. (ed.) Neotyphodium in cool-season grasses. Blackwell Publ., Ames, IA.
Fribourg, H.A., C.S. Hoveland, and K.D. Gwinn. 1991. Tall fescue and the fungal endophyte--A review of current knowledge, p. 30-37. In Tennessee Farm Home Science Program Rep. Tennessee Agric. Exp. Stn., Jackson.
Garner, G.B., G.E. Rothinghaus, C.N. Cornell, and H. Testereci. 1993. Chemistry of compounds associated with endophyte/grass interactions: Ergovaline- and ergopeptine-related alkaloids. Agric. Ecosyst. Environ. 44:65-80.
Hannah, S.M., J.A. Paterson, J.E. Williams, M.S. Kerley, and J.L. Miner. 1990. Effects of increasing dietary levels of endophyte-infected tall rescue seed on diet digestibility and ruminal kinetics of sheep. J. Anim. Sci. 68:1693-1701.
Hemken, R.W., J.A. Bowling, L.S. Bull, R.H. Hatton, R.C. Buckner, and L.P. Bush. 1981. Interaction of environmental temperature and anti-quality factors on the severity of summer toxicosis. J. Anim. Sci. 52:710-714.
Hill, N.S., J.H. Bouton, F.N. Thompson, L. Hawkins, C.S. Hoveland, and M.A. McCann. 2002. Performance of tall rescue germplasm bred for high-and low-ergot alkaloids. Crop Sci. 45:518-523.
Hill, N.S., F.N. Thompson, D.L. Dawe, and J.A. Stuedemann. 1994. Antibody binding of circulating ergopeptine alkaloids in cattle grazing tall rescue. Am. J. Vet. Res. 55:419-424.
Hoveland, C.S., M.A. McCann, and J.H. Bouton. 1997. Influence of endophyte, alfalfa and grazing pressure on star performance and plant persistence of Jesup tall rescue. J. Prod. Agric. 10:546-550.
Kallenbach, R.L., G.J. Bishop-Hurley, M.D. Massic, G.E. Rottinghaus, and C.R West. 2003. Herbage mass, nutritive value, and ergovaline concentration of stockpiled tall rescue. Crop Sci. 43:1001-1005.
National Research Council. 1996. Nutrient requirements of beef cattle. 6th ed. Natl. Acad. of Sci., Natl. Acad. Press, Washington, DC.
Porter, J.K. 1995. Analysis of endophyte toxins: Fescue and other grasses toxic to livestock. J. Anim. Sci. 73:871-880.
Randell-Schadel, B. 1995. Tall rescue endophyte analysis, p. 129. In D.S. Chamblee and J.T. Green (ed.) Production and utilization of pastures and forages in North Carolina. Tech. Bull. 305. North Carolina Agric. Res. Ser., Raleigh, NC.
Rice, R.L., D.J. Blodgett, G.G. Schuring, J.R Fontenot, V.G. Allen, and R.M. Akers. 1997. Evaluation of humoral immune response in cattle grazing endophyte-infected or endophyte-free rescue. Vet. Immunol. Immunopathol. 59:285-291.
Schmidt, S.P., and T.G. Osborn. 1993. Effect of endophyte-infected tall rescue on animal performance. Agric. Ecosyst. Environ. 44:233-262.
Steel, R.G.D., and J.H. Torrie. 1980. Principles and procedures of statistics: A Biometrical Approach. 2nd ed. McGraw-Hill Publ., New York.
Strickland, J.R., J.W. Oliver, and D.L. Cross. 1993. Fescue toxicosis and its impact on animal agriculture. Vet. Hum. Toxicol. 35:454-464.
Stuedemann, J.A., and C.S. Hoveland. 1988. Fescue endophyte: History and impact on animal agriculture. J. Prod. Agric. 1:39-44.
Turner, K.E., J.A. Paterson, M.S. Kerley, and J.R. Forwood. 1990. Mefluidide treatment of tall fescue pastures: Intake and animal performance. J. Anim. Sci. 68:3399-3405.
Van Soest, RJ., and J.B. Robertson. 1980. Systems of analysis for evaluating fibrous feeds, p. 49-60. In W.J. Pigden et al. (ed.) Standardization of analytical methodology in feeds. International Research Development Center, Ottawa, ON, Canada.
J. C. Burns * and D. S. Fisher
J.C. Burns, USDA-ARS and Dep. Crop Science and Dep. Animal Science, North Carolina State Univ., Raleigh, NC 27695. D.S. Fisher. USDA-ARS, Watkinsville, GA 30677. Cooperative investigation of the USDA-ARS and the North Carolina ARS, Raleigh, NC 27695-7643. The use of trade names does not imply endorsements by USDA-ARS or by the North Carolina ARS of the products named or criticism of similar ones not mentioned. Received 29 June 2005. * Corresponding author (email@example.com).
Table 1. The observed range of each forage constituent predicted by near infrared reflectance spectrophotometer, its standard error of calibration (SEC), and standard error of crossvalidation (SEV). Variable ([dagger]) N Range SEC SEV Mean g [kg.sup.-1] IVTDMD 115 619-833 10.9 12.9 745 CP 114 105-193 2.1 2.7 148 NDF 112 564-706 7.3 8.5 627 ADF 115 273-005 4.6 5.9 310 CELL 115 232-349 3.5 4.4 271 Lignin 111 21.1-54.8 1.9 2.1 32.2 ([dagger]) IVTDMD = in vitro true dry matter disappearance; CP = crude protein; NDF = neutral detergent fiber; ADF = acid detergent fiber; CELL = cellulose. Table 2. Thirty-year mean and departures from the mean for climatological data recorded =5 km from the experimental site for the growing period preceding the 20 April and 29 June harvests. ([dagger]) Departure for 30-yr mean growth period Item Rainfall Temp. Rainfall Temp. mm [degrees]C mm [degrees]C April harvest February 88.1 6.1 -28.7 2.3 March 102.4 10.4 78.2 -0.9 April 71.1 15.1 -27.4 0.9 June harvest May 96.3 19.4 -6.6 0.6 June 86.9 23.7 28.5 1.2 ([dagger]) Data recorded at the Raleigh-Durham Int. Airport and reported by the National Oceanic and Atmospheric Administration. Table 3. Dry matter intake and digestion of dry matter, crude protein (CP), and fiber fractions of tall fescue hays harvested in April and June with a wild type, MaxQ, or no endophyte and fed to goats. Apparent Digestion ([dagger]) Item Daily DM intake DM CP NDF kg 100 [kg.sup.-1] BW ([double dagger]) Endophyte Wild type 2.43 ([section]) 636 631 660 MaxQ 2.63 635 654 650 Free 2.55 627 638 645 MSD ([paragraph]) 0.16 24 23 26 Harvest April 2.58 # 679 676 701 June 2.50 587 606 603 Significance (P) Endophyte (E) 0.07 0.70 0.15 0.51 Harvest (H) 0.27 <0.01 <0.01 <0.01 E x H 0.91 0.82 0.65 0.67 Apparent Digestion ([dagger]) Item ADF HEMI CELL g [kg.sup.-1] Endophyte Wild type 639 792 701 MaxQ 624 771 687 Free 618 787 686 MSD ([paragraph]) 30 41 26 Harvest April 672 880 735 June 583 688 648 Significance (P) Endophyte (E) 0.37 0.53 0.41 Harvest (H) <0.01 <0.01 <0.01 E x H 0.69 0.41 0.57 ([dagger]) DM = dry matter; NDF = neutral detergent fiber, ADF = acid detergent fiber; HEMI = hemicellulose; CELL = cellulose. ([double dagger]) Body weight basis. ([section]) Each value is the mean of six animals (n = 6). ([paragraph]) MSD = minimum significant difference based on the Waller-Duncan k ratio (k = 50) t test. # Each value is the mean of six animals and three hay treatments (n = 18). Table 4. Daily digestible intakes of dry matter, crude protein (CP), and fiber fractions of tall fescue hays harvested in April and June with a wild type, MaxQ, or no endophyte and fed to goats. Item DM ([dagger]) CP NDF kg 100 [kg.sup.-1] BW ([double dagger]) Endophyte Wild type 1.54 ([section]) 0.22 1.01 MaxQ 1.67 0.27 1.06 Free 1.60 0.25 1.00 MSD ([paragraph]) 0.12 0.02 0.08 Harvest April 1.75 # 0.29 1.07 June 1.46 0.21 0.97 Significance (P) Endophyte (E) 0.12 <0.01 0.39 Harvest (H) <0.01 <0.01 <0.01 E x H 0.75 0.33 0.91 Item ADF HEMI CELL kg 100 [kg.sup.-1] BW ([double dagger]) Endophyte Wild type 0.48 0.61 0.47 MaxQ 0.49 0.64 0.48 Free 0.48 0.61 0.47 MSD ([paragraph]) 0.05 0.05 0.04 Harvest April 0.50 0.69 0.49 June 0.47 0.55 0.46 Significance (P) Endophyte (E) 0.80 0.37 0.69 Harvest (H) 0.07 <0.01 0.10 E x H 0.95 0.83 0.83 ([dagger]) DM = dry matter; NDF = neutral detergent fiber; ADF = acid detergent fiber; HEMI = hemicellulose; CELL = cellulose. ([double dagger]) Body weight basis. ([section]) Each value is the mean of six animals (n = 6). ([paragraph]) MSD = minimum significant difference based on the Waller-Duncan k ratio (k = 50) t test. # Each value is the mean of six animals and three endophyte treatments (n = 18). Table 5. In vitro true dry matter disappearance, crude protein (CP), and fiber fractions of tall fescue hays with wild type, MaxQ, or no endophyte fed to goats in intake and digestion trials. Item IVTDMD ([dagger]) CP NDF ADF g [kg.sup.-1] April harvest Wild type 741 ([double dagger]) 144 631 312 MaxQ 771 153 620 303 Free 769 154 615 307 MSD ([section]) 28 9 13 10 Harvest April 803 ([paragraph]) 166 595 290 June 718 135 649 324 Significance (P) Endophyte (E) 0.05 0.03 0.03 0.09 Harvest (H) <0.01 <0.01 <0.01 <0.01 E x H 0.61 0.55 0.64 0.39 Item HEMI CELL Lignin g [kg.sup.-1] April harvest Wild type 319 275 29 MaxQ 318 268 28 Free 308 270 30 MSD ([section]) 4 7 3 Harvest April 305 255 27 June 325 286 31 Significance (P) Endophyte (E) <0.01 0.05 0.34 Harvest (H) <0.01 <0.01 <0.01 E x H 0.31 0.31 0.02 ([dagger]) IVTDMD = in vitro true dry matter disappearance; NDF = neutral detergent fiber; ADF = acid detergent fiber; HEMI = hemicellulose; CELL = cellulose. ([double dagger]) Each value is the mean of samples from six animals (n = 6). ([section]) MSD = minimum significant difference based on the Waller-Duncan k ratio (k = 100) t test. ([paragraph]) Each value is the mean of samples from six animals and three hay treatments (n = 18). Table 6. Daily intake of dry matter and digestion of dry matter, CP, and fiber fractions of tall fescue hays harvested in April and June with a wild type, MaxQ, or no endophyte and fed to sheep or cattle. Apparent digestion ([dagger]) Item Daily DM intake DM CP kg 100 [kg.sup.-1] BW([double dagger]) g [kg.sup.-1] Sheep Trial Endophyte Wild type 2.71 ([section]) 630 645 MaxQ 2.78 645 652 Free 2.72 646 669 MSD ([paragraph]) 0.08 19 42 Harvest April 2.89 # 672 666 June 2.57 609 645 Significance (P) Endophyte (E) 0.21 0.21 0.48 Harvest (H) <0.01 <0.01 0.20 E x H 0.18 0.88 0.50 Cattle trial (June harvest) Endophyte Wild type 2.31 ([dagger])([dagger]) 618 595 MaxQ 2.40 623 599 Free 2.44 634 628 Significance (P) Endophyte 0.83 0.77 0.24 MSD 0.49 42 41 Apparent digestion ([dagger]) Item NDF ADF HEMI CELL g [kg.sup.-1] Sheep Trial Endophyte Wild type 642 622 733 682 MaxQ 661 637 779 696 Free 656 634 763 693 MSD ([paragraph]) 30 35 57 35 Harvest April 691 668 833 727 June 614 594 684 655 Significance (P) Endophyte (E) 0.41 0.63 0.23 0.66 Harvest (H) <0.01 <0.01 <0.01 <0.01 E x H 0.82 0.74 0.72 0.76 Cattle trial (June harvest) Endophyte Wild type 666 641 677 724 MaxQ 657 644 670 717 Free 672 646 695 722 Significance (P) Endophyte 0.98 0.57 0.43 0.93 MSD 45 51 41 44 ([dagger]) DM = dry matter; NDF = neutral detergent fiber; ADF = acid detergent fiber; HEMI = hemicellulose; CELL = cellulose. ([double dagger]) Body weight basis. ([section]) Each value is the mean of six animals (n = 6). ([paragraph]) MSD = minimum significant difference based on the Waller-Duncan k ratio (k = 50) t test. # Each value is the mean of six animals and three hay treatments (n = 18). ([dagger])([dagger]) Each value is the mean of five animals (n = 5). Table 7. Daily digestible intakes of dry matter, crude protein (CP), and fiber fractions of tall fescue hays harvested in April and June with a wild type, MaxQ, or no endophyte and fed to sheep or cattle. Item DM ([dagger]) CP NDF kg 100 [kg.sup.-1]BW[(double dagger]) Sheep Trial Endophyte Wild type 1.71 ([section]) 0.26 1.10 MaxQ 1.80 0.27 1.15 Free 1.76 0.29 1.08 MSD ([paragraph]) 0.08 0.04 0.09 Harvest April 1.94 # 0.31 1.20 June 1.57 0.24 1.02 Significance (P) Endophyte (E) 0.11 0.52 0.29 Harvest (H) <0.01 <0.01 <0.01 E x H 0.38 0.56 0.35 Cattle trial (June harvest) Endophyte Wild type 1.43 ([dagger])([dagger]) 0.18 1.00 MaxQ 1.49 0.20 1.01 Free 1.55 0.22 1.05 Significance (P) Endophyte 0.75 0.16 0.87 MSD 0.33 0.04 0.24 Item ADF HEMI CELL kg 100 [kg.sup.-1] BW[(double dagger]) Sheep Trial Endophyte Wild type 0.51 0.63 0.50 MaxQ 0.54 0.70 0.52 Free 0.53 0.65 0.50 MSD ([paragraph]) 0.06 0.07 0.06 Harvest April 0.57 0.75 0.54 June 0.48 0.58 0.47 Significance (P) Endophyte (E) 0.60 0.12 0.59 Harvest (H) <0.01 <0.01 <0.01 E x H 0.45 0.31 0.41 Cattle trial (June harvest) Endophyte Wild type 0.47 0.52 0.48 MaxQ 0.48 0.54 0.48 Free 0.49 0.56 0.49 Significance (P) Endophyte 0.94 0.81 0.97 MSD 0.11 0.13 0.11 ([dagger]) DM = dry matter; NDF = neutral detergent fiber; ADF = acid detergent fiber; HEMI = hemicellulose; CELL = cellulose. ([double dagger]) Body weight basis. ([section]) Each value is the mean of six animals (n = 6). ([paragraph]) MSD = minimum significant difference based on the Waller-Duncan k ratio (k = 50) t test. # Each value is the mean of six animals and three endophyte treatments (n = 18). ([dagger]) ([dagger]) Each value is the mean of five animals (n = 5). Table 8. In vitro true dry matter disappearance, crude protein (CP), and fiber fractions of tall fescue hays harvested in April and June with a wild type, MaxQ, or no endophyte fed to sheep or cattle in intake and digestion trials. Item IVTDMD ([dagger]) CP NDF g [kg.sup.-1] Sheep Trial Endophyte Wild type 765 ([double dagger]) 150 619 MaxQ 765 149 626 Free 769 157 616 MSD ([section]) 47 17 28 Harvest April 803 ([paragraph]) 163 601 June 730 141 641 Significance (P) Endophyte (E) 0.96 0.44 0.57 Harvest (H) <0.01 <0.01 <0.01 E x H 0.68 0.14 0.53 Cattle trial (June harvest) Endophyte Wild type 711 # 129 652 MaxQ 738 135 644 Free 734 143 642 Significance (P) Endophyte <0.01 0.03 0.08 MSD ([paragraph]) 16 10 12 Item ADF HEMI CELL Lignin g [kg.sup.-1] Sheep Trial Endophyte Wild type 303 317 268 28 MaxQ 304 323 269 28 Free 305 311 267 31 MSD ([section]) 21 8 19 3 Harvest April 292 309 257 27 June 316 325 279 31 Significance (P) Endophyte (E) 0.95 0.02 0.94 0.07 Harvest (H) <0.01 <0.01 <0.01 <0.01 E x H 0.65 0.15 0.64 0.57 Cattle trial (June harvest) Endophyte Wild type 319 333 283 29 MaxQ 312 331 279 28 Free 312 330 276 30 Significance (P) Endophyte 0.35 0.46 0.26 0.07 MSD ([paragraph]) 13 8 10 3 ([dagger]) IVTDMD = in vitro true dry matter disappearance; NDF = neutral detergent fiber; ADF = acid detergent fiber; HEMI = hemicellulose; CELL = cellulose. ([double dagger]) Each value is the mean of samples from six animals (n = 6). ([section]) MSD = minimum significant difference based on the Waller-Duncan k ratio (k = 100) t test. ([paragraph]) Each value is the mean of samples from six animals and three hay treatments (n = 18). # Each value is the mean of samples from five animals (n = 5).
|Printer friendly Cite/link Email Feedback|
|Author:||Burns, J.C.; Fisher, D.S.|
|Date:||Jan 1, 2006|
|Previous Article:||The fate of nitrogen applied to a mature Kentucky bluegrass turf.|
|Next Article:||Quantitative trait loci underlying resistance to three soybean cyst nematode populations in soybean PI 404198A.|