HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Figures Only Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (13) Citing Articles via Google Scholar Google Scholar Articles by Belesky, D. P. Articles by Ruckle, J. M. Search for Related Content PubMed Articles by Belesky, D. P. Articles by Ruckle, J. M. Agricola Articles by Belesky, D. P. Articles by Ruckle, J. M. Related Collections Other Forage Crops Plant Nutrition

FORAGES

Mineral Composition of Swards Containing Forage Chicory

USDA-ARS, Appalachian Farming Systems Res. Cent., 1224 Airport Road, Beaver, WV 25813, USA

Corresponding author (dbelesky{at}afsrc.ars.usda.gov)

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS NOTES RESULTS AND DISCUSSION REFERENCES

 
Chicory (Cichorium intybus L.), a highly productive forage under midsummer conditions in the eastern USA, often has higher concentrations of minerals relative to grasses and legumes. Low concentrations of minerals in herbage could reduce production efficiency or create metabolic disorders in livestock. Information on the mineral composition of chicory is limited, but it is needed to improve our understanding of nutritive value and inputs required to sustain chicory production, especially where high rates of N are applied. We conducted field experiments for 3 yr on a Ramsey soil (Loamy, siliceous, subactive, mesic Lithic Dystrudept) in southern West Virginia to determine (i) response to increasing fertilizer N and (ii) production of chicory as a component of swards, including grass and legume as a function of clipping frequency. Mineral concentrations and uptake in available herbage generally increased as N rate increased and were influenced by the botanical composition of the sward. As chicory content decreased in the sward, so did mineral concentrations and uptake. Changes in sward composition associated with chicory influenced important mineral ratios such as N/S, Ca/P, and K/(Ca + Mg) cation equivalent ratio that have significant bearing on livestock health and production efficiency. Clipping frequency and N inputs influenced chicory persistence and ultimately the mineral composition of the sward. Active accumulation of minerals indicates the need for high nutrient input to sustain production, especially on soils with marginal fertility. Health problems associated with mineral nutrient concentrations probably would be minimal in livestock grazing swards that include chicory.

Abbreviations: CP, crude protein • DM, dry matter • IVOMD, in vitro organic matter disappearance

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS NOTES RESULTS AND DISCUSSION REFERENCES

 
SUCCESSFUL CHICORY PRODUCTION for grazing livestock depends on achieving a balance between vigorous growth and herbage quality (Li et al., 1994). Management factors such as N rate and defoliation frequency affect the nutritive value of chicory as well as the total production, stand density, and sward composition (Jung et al., 1996; Collins and McCoy, 1997; Belesky et al., 1999; Belesky et al., 2000). As an example, pure chicory swards grown in central Pennsylvania averaged 230 g kg^-1 crude protein (CP) under intensive defoliation and 140 g kg^-1 CP when managed in an infrequent defoliation regime (Jung et al., 1996). Early season chicory herbage had a very high moisture content (850 g kg^-1), which increased as N fertilization increased (Collins and McCoy, 1997). Turner et al. (1999) reported greater in vitro organic matter disappearance (IVOMD) for chicory–orchardgrass (Dactylis glomerata L.) mixtures than for either forage alone. Apparently, nutritive value is improved in swards that include chicory; however, the overall breakdown of neutral-detergent fiber was slowed when chicory swards were treated with high amounts of ammonium nitrate (NH₄NO₃) fertilizer.

Information on the mineral composition of chicory is limited, but it is needed to understand the nutritive value of chicory herbage and to identify nutrient inputs that sustain production, especially when high rates of N are applied. Crush and Evans (1990) and Reid et al. (1993) reported that the mineral composition of forage chicory was comparable to or exceeded that of white and red clover (Trifolium repens and T. pratense, respectively) and perennial ryegrass (Lolium perenne L.). Mineral concentrations in chicory met or exceeded recommended dietary mineral requirements of lactating dairy cows (Jung et al., 1996), and because chicory had a relatively high B concentration, fertilization with B might be warranted. Herbage may contain mineral concentrations that theoretically meet livestock requirements, but some portion of the total may not be available because of where and how the mineral element occurs in the plant (Spears, 1994). The relative concentrations or ratios of certain mineral nutrients in diets, such as Ca/P or K/(Ca + Mg), can also affect metabolism or influence the absorption and bioavailability of nutrients to the grazer. The relatively low fiber concentration and high IVOMD and moisture content of chicory (Volesky 1996; Collins and McCoy, 1997; Belesky et al., 1999) suggest that mineral bioavailability should be high.

Herbage is an important means of delivering minerals to grazing livestock in extensive and low-input situations. Mineral deficiencies can depress forage digestibility and herbage intake (Provenza, 1995) and compromise livestock production efficiency, especially in marginal resource situations. One means of ensuring adequate mineral nutrition of the diet is to increase the floristic diversity of a sward (Hasler, 1971). In many cases, floristic diversity is a function of the soil resource (Stout et al., 1977). Baker and Reid (1977) and Reid et al. (1970) reported that mineral concentrations essential to livestock health were present in greater quantities in weeds and legumes than in grasses. Canopy utilization and soil fertility also interact to affect the composition of swards, including those sown to chicory, and ultimately the nutritive value of chicory herbage (Belesky et al., 1999, 2000).

We conducted field experiments to determine the influence of (i) N on pure swards of chicory and (ii) clipping frequency on pure chicory and mixed-species swards containing chicory. Mineral composition was determined on composite herbage samples representing swards ranging from pure chicory to mixtures containing chicory and naturalized cool-season grasses and legumes.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS NOTES RESULTS AND DISCUSSION REFERENCES

 
Site Preparation and Treatments
Two field experiments were conducted for 3 yr (1994–1996) on a gently sloping upland site of Ramsey soil (Loamy, siliceous, subactive, mesic Lithic Dystrudept) in southern West Virginia (38° N, 81° W; 850 m above sea level). Temperature and precipitation data collected at the site and long-term means recorded at the National Weather Service Office (National Oceanographic and Atmospheric Administration) located about 5 km west of the experimental sites are presented in Belesky et al. (1999)(2000). Initial soil pH was about 6.6, and there were moderate levels of Bray-1 available P (Olsen and Sommers, 1982) and exchangeable K (ammonium acetate extractable) in the surface 15 cm. Plot areas were prepared by spraying existing vegetation with glyphosate [N-(phosphono-methyl) glycine] at 1.19 kg a.i. ha^-1 in late spring of 1993, roto-tilling the sod to about 10 cm, followed by smoothing and raking to prepare a firm seedbed. No insecticides or herbicides were used once plots were sown.

Experiment 1 was set out as a randomized complete block designed to determine growth and yield response of chicory to fertilizer N application. Details concerning this experiment can be found in Belesky et al. (2000). Plots were broadcast-sown to `Grasslands Puna' chicory (10 kg ha^-1 seed) in early June of 1993 and culti-packed to improve seed-to-soil contact. Each plot was 2 by 4 m, and five plots were in each of three replicate blocks. Stands were clipped with a rotary mower once in late summer of 1993 to control weeds and at 6-wk intervals beginning in late spring of 1994 (three harvests) and during four harvests in 1995 and 1996. Nitrogen (35 kg N ha^-1 as NH₄NO₃) was applied in the establishment year after plants were actively growing (vigorous leaf appearance about 4 wk after sowing). In addition, 80, 150, and 2 kg ha^-1 of P, K, and B were applied at establishment and in the spring of each subsequent year of the experiment. Nitrogen (NH₄NO₃) was applied in a single dose at rates of 60, 120, 240, or 480 kg ha^-1 when leaf formation began in mid-April of each year. A control (0 N applied) and each N rate were replicated three times.

Experiment 2 was a randomized complete block design with plots split to address the interaction of clipping frequency x sward composition. Additional details can be found in Belesky et al. (1999). Plots (3 by 5 m) were broadcast-sown in early June of 1993 to Grasslands Puna chicory, Norcen birdsfoot trefoil (Lotus corniculatus L.), and `Hallmark' orchardgrass, creating stands of pure chicory and chicory–orchardgrass and chicory–orchardgrass–trefoil mixtures. Chicory was sown at 10 kg ha^-1 in pure plots and at 5 kg ha^-1 in mixtures. Trefoil was sown at 5 kg ha^-1 and orchardgrass was sown at 15 kg ha^-1. Fertilizer (70 and 100 kg ha^-1 of P and K) was broadcast at seeding. Nitrogen (35 kg N ha^-1 as NH₄NO₃) was applied in the establishment year after plants were actively growing. Fertilizer (35 kg N ha^-1 as NH₄NO₃, 80 kg P ha^-1, and 150 kg K ha^-1) was applied in the spring of each subsequent year of the experiment.

Clipping and sampling were carried out for three consecutive years beginning in 1994. Stands were clipped once (to 5-cm stubble) in late summer of 1993 to control weeds. Plots in Experiment 2 were divided (1.5- by 5-m plots) to accommodate a 3- and 6-wk clipping frequency. The 3-wk frequency was first harvested in late May of each year. The first harvest of the 6-wk clipping frequency coincided with birdsfoot trefoil flowering, and subsequent clips approximated regrowth interval requirements for trefoil.

Sample Collection and Analysis
Sample strips (0.6 by 3.0 m) located in the center of each plot in Experiments 1 and 2 were clipped to a 5-cm residue height with a collection bag equipped rotary mower. Herbage samples were dried at 60°C in a forced-air oven and ground in a cyclone mill to pass a 0.5-mm screen before chemical analyses. Botanical composition of the stands was determined at 6-wk intervals using the point-quadrat method described by Warren-Wilson (1959). Each of 45 contact points in a plot was categorized as chicory, grass [orchardgrass, tall fescue (Festuca arundinacea Schreb.), and Kentucky bluegrass (Poa pratensis L.)], or legume (includes red and white clover, which occur naturally on the site, and the birdsfoot trefoil that was sown). Weeds (forbs and grasses not specifically listed above) and bare ground were noted but not included in the data analysis because their contribution to total composition was nominal. Details of botanical composition of the swards can be found in Belesky et al. (2000) for Experiment 1 and in Belesky et al. (1999) for Experiment 2.

Herbage concentrations of P, S, Zn, B, Mg, Ca, Cu, and K were obtained by inductively coupled plasma spectroscopy (Model JY 46 P, JY-Horiba, Jobin Yvon Emission Division, Edison, NJ¹). Ground plant tissue (100 mg) was treated with 1 mL 15.4 M HNO₃ and digested by a microwave process. The digestion was done in sealed Teflon-lined digestion vessels (Parr Microwave Acid Digestion Bomb, Parr Instrument Co., Moline, IL). Samples were digested in a conventional microwave (1100 W) as follows: 4 min at 70% power, 2 min at 100% power, and 5 min without power. Digestion vessels were removed from the microwave and allowed to cool. The contents of each cup were rinsed into a 10-mL glass volumetric flask, filtered, combined with 10 µg g^-1 Y standard, and brought to volume using analytical grade I water. Reference tomato (Lycopersicon esculentum L.) leaf tissue (NIST Standard Reference Material SRM 1573a; U.S. Dep. of Commerce, Natl. Inst. of Standards and Technol., Gaithersburg, Maryland) was used to standardize the mineral analyses.

Nitrogen in the 1994 samples was determined by total combustion of the sample on a LECO CHN 600 (LECO Corp., St. Joseph, MI); a Carlo Erba EA1108 CHNS Analyzer (CE-Elantech, Lakewood, NJ) was used for the 1996 samples. Reference tomato leaf tissue analysis showed that N analysis methods gave comparable results. Detailed N data for chicory herbage are presented in Belesky et al. (1999)( 2000).

Data from Experiment 1 were analyzed as a randomized complete block design using general linear models (GLM) procedures of SAS (Littell et al., 1991). Univariate procedures were used to evaluate the influence of treatment within N rates (repeated measures for harvest dates) on herbage mineral concentrations. Variances for elements and dry matter yield were heterogeneous for years; consequently, years were analyzed separately. Regression equations were developed using orthogonal polynomial contrasts for the influence of N rate on specific elements. Data from Experiment 2 were analyzed as a split-plot using SAS-GLM procedures. Univariate procedures were applied to evaluate the influence of clipping frequency within sward composition (repeated measures for harvest dates). The variances for dry matter yields in Experiment 2 were heterogeneous for years; consequently, years were analyzed separately.

	RESULTS AND DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS NOTES RESULTS AND DISCUSSION REFERENCES

 
Mineral concentrations reported here reflect available herbage as a function of botanical composition over time: In Experiment 2, varied botanical composition was intentional, but in Experiment 1, it was not. Consequently, concentrations are a function of plant maturity and age as well as changing botanical composition of the sward. This relationship is shown in Fig. 1 where the amount of chicory in the sward was a function of time and N rate and influenced the total quantity of macronutrients. As the proportion of chicory declined, so did total mineral content. Briefly, in Experiment 1, the sward in 1994 was virtually pure chicory, regardless of N rate. By 1996, the contribution of chicory to the sward was much less and ranged from 15% at 480 kg N ha^-1 to about 40% when no N was applied. The loss of chicory was compensated by an increase in grasses. Detailed botanical composition data are reported in Belesky et al. (2000). In Experiment 2, we established swards differing in species composition. Chicory declined as a component of the sward with time, regardless of clipping frequency and initial sward composition. Chicory represented about 30% of the herbage remaining in the sward after 3 yr in Experiment 2, which agrees with Kunelius and MacRae (1999) for grass–legume–chicory mixtures grown in Atlantic Canada. Botanical details of Experiment 2 are reported in Belesky et al. (1999).

View larger version (17K): [in this window] [in a new window]   Fig. 1. Macronutrient (P + K + Ca + Mg + S) concentration (g kg-1) in available herbage as a function of N fertilizer (kg ha-1) and chicory in the sward. Macronutrient concentration = 0.32 (% chicory)2 - 1.78 x 10-2 (% chicory) + 31.07;

Sward composition, harvest frequency, and interaction of harvest frequency x time during the growing season had significant but small effects on P for herbage collected in 1994 in Experiment 2 (Table 2). In 1994, swards that were clipped at 3-wk intervals had 30% less P uptake than those clipped at 6-wk intervals. Harvest frequency effects are probably attributable to the amount of chicory present in the sward as well as total herbage production (Belesky et al., 1999). Phosphorus uptake was significantly influenced by the interaction of harvest frequency x harvest date (Table 2), probably as a function of the influence on sward composition (Belesky et al., 1999). Phosphorus concentrations met or exceeded the requirements of 1.7 to 3.9 g kg^-1 for beef cattle in various physiological stages of production (NRC, 1996) as well as the recommended range of 1.6 to 3.8 g kg^-1 for sheep (NRC, 1985).

Sulfur concentrations ranged between 2 and 5 g kg^-1 dry matter (DM) in each year of Experiment 1 and declined as N rate increased (Table 2). Sulfur concentrations were similar in swards of pure chicory, chicory–orchardgrass, and chicory–orchardgrass–trefoil managed as hay; they ranged from 3 to 6 g kg^-1 DM over the 1994 growing season but averaged 1.5 g kg^-1 DM by 1996 when the amount of chicory in the sward declined (Table 4). Sulfur uptake in 1996 declined 38% as N was increased from 0 to 480 kg ha^-1 (data not shown). The decrease in S concentration and uptake may be related to changes in botanical composition of the sward (Belesky et al., 1999) or changes in soil S availability. Herbage S uptake in swards that were clipped frequently was 52% less than that in herbage managed as hay. Sulfur concentrations (Table 4) in swards containing chicory, typified by the sward composition found in 1994, exceeded the requirements of 1.7 to 3.9 g kg^-1 for beef cattle (NRC, 1996) and generally met the recommended range of 1.4 to 2.6 g kg^-1 for sheep (NRC, 1985). Swards with low amounts of chicory are likely to be marginal in terms of meeting mineral nutrient requirements of livestock.

Nitrogen/Sulfur
The N/S ratios in Experiment 1 increased as fertilizer N application rate increased in 1994 and declined with increasing N in 1996. The N/S ratio of pure chicory (represented by 1994 data) ranged from 4.4 when no N was applied to about 12.6 at 480 kg N ha^-1 and increased linearly as N rate increased (Fig. 2). Ratios in 1996 represent typical cool-season grass and legume swards with response to N rate confounded by changing botanical composition, specifically a decline in the amount of chicory. The N/S ratios for swards containing chicory are within the recommended range for sheep (NRC, 1985) and cattle (NRC, 1996) and appear suitable for extensive production situations. Optimal N/S ratios in livestock diets are reported as 11:1 for sheep and 15:1 for cattle (Kincaid, 1988). Increasing levels of dietary S influenced dietary Cu, Zn, and Se availability to sheep (Suttle, 1974).

View larger version (12K): [in this window] [in a new window]   Fig. 2. Nitrogen/S ratios as a function of N rate in Experiment 1. In 1994, ; . In 1996, ;

View larger version (13K): [in this window] [in a new window]   Fig. 3. Nitrogen/S ratios in Experiment 2 as a function of harvest frequency and time (d) over the growing season in 1994 for 3-wk and 6-wk clipping intervals; and in 1996 for 3-wk and 6-wk clipping intervals

The Ca/P ratios averaged 3.3 ± 0.4 in 1994 (when chicory was dominant) and 2.6 ± 0.3 in 1996 (when canopies had substantially less chicory) and were not affected by N rate. The Ca/P ratios in pure chicory and mixtures containing chicory were similar to those found in grass–legume hays (Stout et al., 1977). Ratios for pure chicory were 15% greater than for mixed swards when no N was applied and were 54% greater in pure chicory swards than in mixed swards when 480 kg N ha^-1 was applied. Herbage in Experiments 1 and 2 had relatively high Ca concentrations and average P concentrations. Calcium concentrations were as high as 1.5 g kg^-1 DM and were greatest at the lowest N levels in 1994 and 1996 (data not shown).

The Ca/P ratios in herbage generated in Experiment 2 averaged 3:1 in 1994 and were <2:1 by 1996 (Fig. 4). The ratios were a product of greater concentrations of Ca combined with lesser amounts of P in the tissue. Ratios were greater when swards were clipped at 6-wk rather than 3-wk intervals in 1994 and reflect the contribution made by chicory to the sward. By 1996, clipping frequency had minimal influence on Ca/P ratio.

View larger version (18K): [in this window] [in a new window]   Fig. 4. Calcium/P ratios in 1994 and 1996 as a function of sward composition and harvest frequency in Experiment 2. Bars at the top of each column are the standard error of the mean

View larger version (18K): [in this window] [in a new window]   Fig. 5. The relationship of K/(Ca + Mg) on an equivalent basis in 1994 and 1996 as a function of sward composition and harvest frequency in Experiment 2

The Cu concentrations in herbage collected in Experiment 2 (Table 4) were within the average range for herbage mineral concentrations reported by Mayland and Wilkinson (1996); Cu concentrations were slightly greater (14%) in herbage clipped at 3-wk rather than 6-wk intervals and were less in swards with less chicory in 1994. Herbage Cu concentrations were 75% less in 1996 (7 mg kg^-1) than in 1994 (30 mg kg^-1) but still met or exceeded recommended requirements for sheep (NRC, 1985) and beef cattle (NRC, 1996). As sward composition changed and chicory plants matured, Cu and Zn concentrations declined in available herbage.

Boron concentrations in Experiment 1 were not influenced by N rate in 1994 and averaged 25 ± 2 mg kg^-1. In 1996, B concentrations declined by 50% from 24 to 11 mg kg^-1, as N rate increased from 0 to 480 kg ha^-1, reflecting mineral composition of swards dominated by grasses rather than chicory. The yield of B in available herbage increased in 1994 as a function of chicory response to N, whereas in 1996, B yield declined as N rate increased, reflecting the strong N response of grasses that contain much less B than does chicory (Hare et al., 1987). Boron concentrations in our experiments were less than those reported for chicory by Jung et al. (1996).

Our results agree with earlier reports noting that mineral concentrations in chicory exceeded those found in grasses and legumes (Hare et al., 1987; Crush and Evans, 1990; Jung et al., 1996; Barry, 1998) and with those reported by Jung et al. (1996) for chicory grown in central Pennsylvania. The influence of N on herbage production and the resultant impact on nutrient composition and mineral yield in herbage are important considerations when developing management practices for forages. Sallette and Huché (1989) showed that N and mineral contents were related primarily as a function of dilution as the forage crop grew. Greater amounts of herbage accumulation often led to dilution of minerals (lower concentrations). If the soil supply of nutrients is not limiting, uptake may actually increase with increasing amounts of N, depending on the growth requirements and accumulation ability of the plant. Experiments are underway to identify mechanisms of nutrient acquisition in chicory. In terms of production management, accumulation of mineral nutrients indicates the need for nutrient input to sustain production, especially on soils with marginal fertility. Health problems of grazing livestock that are associated with mineral composition of swards containing chicory probably would be minimal.

	ACKNOWLEDGMENTS

 
We thank G.D. Lambert for diligent assistance with field plot and sample collection and preparation aspects of this project and B.A. White for plant and soil mineral analysis.

	NOTES

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS NOTES RESULTS AND DISCUSSION REFERENCES

 
¹ Trade or proprietary names are used for the convenience of the reader and do not imply endorsement by USDA-ARS over comparable products.

Received for publication June 8, 2000.

	REFERENCES

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS NOTES RESULTS AND DISCUSSION REFERENCES

 

• Baker, B.S., and R.L. Reid. 1977. Mineral concentrations of forage species grown in central West Virginia on various soil series. West Virginia Univ. Agric. Exp. Stn. Bull. 657.
• Barry, T.N. 1998. The feeding value of chicory (Cichorium intybus) for ruminant livestock. J. Agric. Sci. (Cambridge). 131:251–257.
• Belesky, D.P., K.E. Turner, J.M. Fedders, and J.M. Ruckle. 1999. Productivity, botanical composition, and nutritive value of swards including forage chicory. Agron. J. 91:450–456.[Abstract/Free Full Text]
• Belesky, D.P., K.E. Turner, and J.M. Ruckle. 2000. Influence of nitrogen on productivity and nutritive value of forage chicory. Agron. J. 92:472–478.[Abstract/Free Full Text]
• Collins, M., and J.E. McCoy. 1997. Chicory productivity, forage quality, and response to nitrogen fertilization. Agron. J. 89:232–238.[Abstract/Free Full Text]
• Crush, J.R., and J.P.M. Evans. 1990. Shoot growth and herbage element concentrations of `Grasslands Puna' chicory (Cichorium intybus L.) under varying soil pH. Proc. N.Z. Grassl. Assoc. 51:163–166.
• Emerick, R.J. 1988. Urinary calculi. p. 523–531. In D.C. Church (ed.) The ruminant animal: Digestive physiology and nutrition. Prentice Hall, Englewood Cliffs, NJ.
• Grunes, D.L., and R.M. Welch. 1989. Plant contents of magnesium, calcium, and potassium in relation to ruminant nutrition. J. Anim. Sci. 67:3485–3494.
• Hare, M.D., M.P. Rolston, J.R. Crush, and T.J. Fraser. 1987. Puna chicory—a perennial herb for New Zealand pastures. Proc. N.Z. Agron. Soc. 17:45–49.
• Hasler, A. 1971. Mineral content of the fodder of natural and artificial meadows in Switzerland. p. 107–120. In Proc. General Meeting Eur. Grassl. Federation, 4th, Lausanne, Switzerland.
• Jung, G.A., J.A. Shaffer, G.A. Varga, and J.R. Everhart. 1996. Performance of Grasslands Puna chicory at different management levels. Agron. J. 88:104–111.[Abstract/Free Full Text]
• Kincaid, R. 1988. Macro elements for ruminants. p. 326–341. In D.C. Church (ed.) The ruminant animal: Digestive physiology and nutrition. Prentice Hall, Englewood Cliffs, NJ.
• Kunelius, H.T., and K.B. MacRae. 1999. Forage chicory persists in combination with cool season grasses and legumes. Can. J. Plant Sci. 79:197–200.
• Li, G.D., P.D. Kemp, and J. Hodgson. 1994. Control of reproductive growth in Puna chicory by grazing management. Proc. N.Z. Grassl. Assoc. 56:213–217.
• Littell, R.C., R.J. Freund, and P.C. Spector. 1991. SAS systems for linear models. 3rd ed. SAS Inst., Cary, NC.
• Mayland, H.F., and P.R. Cheeke. 1995. Forage-induced animal disorders. p. 121–135. In R.F Barnes et al. (ed.) Forages. Vol. 2. The science of grassland agriculture. Iowa State Univ. Press, Ames.
• Mayland, H.F., and S.R. Wilkinson. 1996. Mineral nutrition. p. 165–191. In L.E. Moser et al. (ed.) Cool-season forage grasses. Agron. Monogr. 34. ASA, CSSA, and SSSA, Madison, WI.
• National Research Council (NRC). 1985. Nutrient requirements of sheep. 6th ed. National Academy Press, Washington, DC.
• National Research Council (NRC). 1996. Nutrient requirements of beef cattle. 7th Revised ed. National Academy Press, Washington, DC.
• O'Dell, B.L. 1984. Bioavailability of trace elements. Nutr. Rev. 42:301–308.[Medline]
• Olsen, S.R., and L.E. Sommers. 1982. Phosphorus. p. 403–430. In A.L. Page et al. (ed.) Methods of soil analysis. Part 2. 2nd ed. SSSA Book Ser. 5. SSSA, Madison, WI.
• Provenza, F.D. 1995. Postingestive feedback as an elementary determinant of food preference and intake in ruminants. J. Range Manage. 48:2–17.
• Reid, R.L., G.A. Jung, J.R. Puoli, and F.K. Poland. 1993. Chicory pastures for sheep: Composition and quality. J. Anim. Sci. 71(suppl. 1):195(abstr.
• Reid, R.L., A.J. Post, and G.A. Jung. 1970. Mineral composition of forages. West Virginia Univ. Agric Exp. Stn. Bull. 589T.
• Sallette, J., and L. Huché. 1989. The diagnosis of grassland mineral nutrient status through herbage analysis. p. 65–66. In Proc. Int. Grassl. Congr., 16th, Nice, France. 4–11 Oct. 1989. French Grassl. Soc.
• Spears, J.W. 1994. Minerals in forages. p. 281–317. In G.C. Fahey, Jr. et al. (ed.) Forage quality, evaluation, and utilization. ASA, CSSA, and SSSA, Madison, WI.
• Stout, W.L., D.P. Belesky, G.A. Jung, R.S. Adams, and B.L. Moser. 1977. A survey of Pennsylvania forage mineral levels with respect to dairy and beef cow nutrition. Pennsylvania State Univ. Agric. Exp. Stn. Prog. Rep. 364.
• Suttle, N.F. 1974. Effects of organic and inorganic sulphur on the availability of dietary copper to sheep. Br. J. Nutr. 32:559–568.[Medline]
• Turner, K.E., D.P. Belesky, and J.M. Fedders. 1999. Chicory (Cichorium intybus L.) effect on lamb weight gain and rate of in vitro neutral detergent fiber disappearance. Agron. J. 91:445–450.[Abstract/Free Full Text]
• Underwood, E.J. 1966. The mineral nutrition of livestock. FAO and CAB, London.
• Volesky, J.D. 1996. Forage production and grazing management of chicory. J. Prod. Agric. 9:401–406.
• Warren-Wilson, J. 1959. Analysis of spatial distribution of foliage by two-dimensional point quadrats. New Phytol. 58:92–101.

This article has been cited by other articles:

				M. Labreveux, M. A. Sanderson, and M. H. Hall Forage Chicory and Plantain: Nutritive Value of Herbage at Variable Grazing Frequencies and Intensities Agron. J., February 7, 2006; 98(2): 231 - 237. [Abstract] [Full Text] [PDF]

				M. Labreveux, M. H. Hall, and M. A. Sanderson Productivity of Chicory and Plantain Cultivars under Grazing Agron. J., May 1, 2004; 96(3): 710 - 716. [Abstract] [Full Text] [PDF]

				M. A. Sanderson, M. Labreveux, M. H. Hall, and G. F. Elwinger Nutritive Value of Chicory and English Plantain Forage Crop Sci., September 1, 2003; 43(5): 1797 - 1804. [Abstract] [Full Text] [PDF]

This Article Abstract Figures Only Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (13) Citing Articles via Google Scholar Google Scholar Articles by Belesky, D. P. Articles by Ruckle, J. M. Search for Related Content PubMed Articles by Belesky, D. P. Articles by Ruckle, J. M. Agricola Articles by Belesky, D. P. Articles by Ruckle, J. M. Related Collections Other Forage Crops Plant Nutrition