J. Anim Sci.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ogden, R. K.
Right arrow Articles by Richardson, M. D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ogden, R. K.
Right arrow Articles by Richardson, M. D.
J. Anim. Sci. 2005. 83:1142-1152
© 2005 American Society of Animal Science

ANIMAL NUTRITION

Ruminal in situ disappearance kinetics of dry matter and fiber in growing steers for common crabgrass forages sampled on seven dates in northern Arkansas1

R. K. Ogden*, W. K. Coblentz*,2, K. P. Coffey*, J. E. Turner*,3, D. A. Scarbrough*,4, J. A. Jennings{dagger} and M. D. Richardson{ddagger}

* Departments of Animal Science and and {ddagger} Horticulture, University of Arkansas Division of Agriculture, Fayetteville 72701; and and {dagger} Animal Science Section, Arkansas Cooperative Extension Service, University of Arkansas Division of Agriculture, Little Rock 72204


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results and Discussion
 Implications
 Literature Cited
 
Southern crabgrass (Digitaria ciliaris [Retz.] Koel.) is often viewed as an undesirable weed, largely because it encroaches upon field and forage crops, gardens, and lawns. However, visual observations of livestock grazing mixed-species pastures suggest that cattle seem to prefer crabgrass to many other summer forages. The objectives of this study were to assess the nutritive value of crabgrass sampled weekly between July 11, and August 22, 2001, and then to determine ruminal in situ disappearance kinetics of DM and NDF for these crabgrass forages. A secondary objective was to compare these kinetic estimates with those of alfalfa (Medicago sativa L.), bermudagrass (Cynodon dactylon [L.] Pers.), and orchardgrass (Dactylis glomerata L.) control hays. All forages were evaluated in situ using five (383 ± 22.7 kg) ruminally cannulated crossbred (Gelbvieh x Angus x Brangus) steers. Whole-plant crabgrass exhibited more rapid (P ≤ 0.002) ruminal disappearance rates of DM (overall range = 0.069 to 0.084 h–1) than did bermudagrass (0.054 h–1) and orchardgrass (0.060 h–1) hays, but disappearance rates were slower (P <0.001) for crabgrass than for alfalfa hay (0.143 h–1). Effective ruminal disappearance of DM was greater (P <0.001) for crabgrass (overall range = 69.3 to 75.4%) than for all the control hays. Similarly, disappearance rates of NDF for crabgrass (overall range = 0.069 to 0.086 h–1) were more rapid (P <0.001) than observed for bermudagrass and orchardgrass hays; however, NDF in alfalfa disappeared at a faster (P <0.001) rate (0.107 h–1) than crabgrass. These results indicate that crabgrass offers greater effective ruminal degradability of DM and NDF than orchardgrass or alfalfa of moderate quality. More importantly, it potentially offers faster and more extensive ruminal disappearance than perennial warm-season grasses typically found throughout the southeastern United States, and it should likely support improved performance by ruminant livestock in this region.

Key Words: Alfalfa • Bermudagrass • Crabgrass • Fiber • In Situ Disappearance Kinetics • Orchardgrass


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results and Discussion
 Implications
 Literature Cited
 
Common crabgrass is a warm-season annual grass that appears regularly during summer months in pastures and hayfields. In the southeastern United States, it is considered undesirable in fields of bermudagrass harvested for hay because it dries slowly, thereby raising concerns about the potential for spontaneous heating and molding during storage (Dalrymple et al., 1999Go). In addition, its color and texture are distinctive; these traits are often associated with weeds, and therefore are undesirable (Andrae, 2002Go). For these reasons, bales of hay with significant quantities of crabgrass often are unacceptable to the horse industry. A growing collection of visual observations, demonstrations, and other circumstantial evidence suggest that beef and dairy cattle may prefer crabgrass to many other summer forages, and often exhibit ADG >1 kg/d when consuming this forage (Dalrymple et al., 1999Go).

Ruminal disappearance rates of DM and NDF for perennial warm-season grasses are generally slower (Coblentz et al., 1998Go; Mandebvu et al., 1999Go; Galdámez-Cabrera et al., 2003Go) than those reported for cool-season grasses (Hoffman et al., 1993Go), and are particularly slow compared with legumes such as alfalfa or red clover (Trifolium pratense L.; Coblentz et al., 1998Go). Therefore, the evaluation of alternative annual or perennial grasses that grow throughout the summer months and offer the potential to improve digestion, intake, and production of meat and milk by ruminants is essential, particularly in the southeastern United States. Our objectives for this study were to 1) assess the nutritive value of leaf blade, stem, and whole-plant tissues for crabgrass sampled weekly between July 11, and August 22, 2001; 2) assess the ruminal in situ disappearance kinetics of DM and NDF for whole-plant crabgrass sampled on these dates; and 3) compare these kinetic estimates with those of alfalfa, bermudagrass, and orchardgrass hays evaluated simultaneously.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results and Discussion
 Implications
 Literature Cited
 
Collection of Experimental Forages

A naturally reseeded stand of crabgrass, on a producer farm near Prairie Grove, AR, was divided into four 3.7-m x 7.3-m field blocks and fertilized with ammonium nitrate at a rate of 84 kg of N/ha on June 16, 2001. During summer 2001, accumulated growth of crabgrass was sampled weekly for 7 wk beginning on July 11 and ending on August 22 by clipping (with garden shears) two 0.25-m2 frames per block to a 2.5-cm stubble height. No area within each block was clipped more than once; therefore, all clipped forage was original growth. Within each frame, canopy height was measured at three random locations, and three randomly selected plants were evaluated for growth stage. Favorable climatic conditions, such as rainfall events, released new tillers throughout the sampling period. This was particularly evident on the later sampling dates when the growth stage for individual tillers within the sward became increasingly diverse; therefore, the reported growth stage for each date represents an average maturity for tillers across the entire sward. Precipitation data at the site between June 16 and August 22 were collected with a commercial rain gauge, and recorded by the cooperating producer (Table 1Go).


View this table:
[in this window]
[in a new window]
  		Table 1. Precipitation from individual events and cumulative totals between June 16 and August 22, 2001, at a producer site with experimental plots of common crab-grass located near Prairie Grove, AR
 
All clipped forage samples were dried under forced air at 50°C, and dry weights for each frame were used to estimate available forage. Any weeds or dead vegetative matter were removed by hand separation before calculating available forage and conducting all subsequent analyses. The leaf-to-stem ratio was determined by separating each leaf blade at the leaf collar. Other plant parts, including the leaf sheath and any reproductive tissues, were considered to be stem in the determination of leaf-to-stem ratio, and for subsequent laboratory analysis of leaf and stem for individual characteristics of nutritive value. Control hays were harvested as small square bales at the University of Arkansas Forage Research Area in Fayetteville. All bales of Affinity alfalfa, common bermudagrass, and Benchmark orchardgrass were harvested during spring or summer 2002. When opened, these hays exhibited no evidence of spontaneous heating or molding, and all forage selected for the in situ study was taken from the center portion of each bale. The orchardgrass hay was taken from a second cutting made on June 19, 2002, and was entirely vegetative regrowth.

Laboratory Analyses

All dried crabgrass samples, as well as the alfalfa, bermudagrass, and orchardgrass control hays, were ground to pass a 1- or 2-mm screen in a Wiley mill (Arthur H. Thomas, Philadelphia, PA). Portions of samples ground to pass a 1-mm screen were analyzed sequentially for NDF, ADF, hemicellulose, cellulose, and ADL by the batch procedures outlined by Ankom Technology Corp. (Fairport, NY); sodium sulfite and {alpha}-amylase were omitted from the neutral detergent solution. Concentrations of N were determined by rapid combustion (Elementar Americas, Inc., Mt. Laurel, NJ), and CP was calculated as the percentage of N in the sample x 6.25. Subsamples ground to pass a 2-mm screen were stored in sealed freezer bags at room temperature before subsequent in situ analysis.

In Situ Procedures

Five 383 ± 22.7 kg ruminally cannulated crossbred (Gelbvieh x Angus x Brangus) steers were used to evaluate the in situ disappearance kinetics of ground (2-mm screen) whole-plant crabgrass sampled weekly, and the alfalfa, bermudagrass, and orchardgrass control hays. Surgical placement of the cannulas and care of the steers were approved by the University of Arkansas Animal Care and Use Committee. Steers were housed in individual 3.4-m x 4.9-m pens with concrete floors that were cleaned regularly. Steers were offered a diet of alfalfa hay (16.2% CP, 51.9% NDF, and 38.7% ADF; DM basis) and a corn-based supplement (94.7% cracked corn, 3.0% molasses, and 2.3% trace mineral salt; as-fed basis). On an as-fed basis, the basal diet contained 85% alfalfa hay and 15% supplement, and it was offered at 0630 and 1430 in equal portions at a cumulative daily rate of 2.0% of BW. Fresh water was available free choice, and steers were adapted to the basal diet for 10 d before initiating the trial.

In situ procedures were consistent with the standardized techniques described by Vanzant et al. (1998)Go. Five-gram samples of each forage were weighed into Dacron bags (10 cm x 20 cm; 50 ± 10-µm pore size; Ankom Technology) that were heat sealed with an impulse sealer (type TISH-200, TEWI Int. Co., Ltd., Taipei, Taiwan). Before insertion into the rumen, all Dacron bags were placed in 35-cm x 50-cm mesh laundry bags and incubated in tepid water (39°C) for 20 min. Samples were then suspended in the ventral rumen immediately before the 0630 feeding and incubated for 3, 6, 9, 12, 24, 36, 48, 72, or 96 h. Upon removal from the rumen, bags were rinsed immediately in a top-loading washing machine (model LXR7144EQ1, Whirlpool Corp., Benton Harbor, MI) using the procedures outlined by Coblentz et al. (1997)Go. Rinsing procedures included 10 cold-water rinse cycles (47 L of water), where each cycle comprised 1 min of agitation and 2 min of spin (Coblentz et al., 1997Go; Vanzant et al., 1998Go). A separate set of bags was preincubated and rinsed without ruminal incubation (0 h). After rinsing, the sample residues were dried to a constant weight at 50°C, and equilibrated with the atmosphere before further analysis for residual DM and NDF (Vanzant et al., 1996Go). The concentration of NDF in these in situ residues was determined in a manner identical to that described previously.

The percentage of DM or NDF remaining at each incubation time was fitted to the nonlinear regression model of Mertens and Loften (1980)Go using PROC NLIN of SAS (SAS Inst., Inc., Cary, NC). Dry matter and NDF were partitioned into three fractions based on relative susceptibility to ruminal disappearance. The A fraction was defined as the immediately soluble portion, although it also may have included some minute insoluble particles that could have washed out of the Dacron bags (Coblentz et al., 1998Go; Galdámez-Cabrera et al., 2003Go). Fraction B represented that portion of DM and NDF that disappeared at a measurable rate, and fraction C was defined as the portion of DM and NDF that was undegraded in the rumen. Fractions B and C, disappearance rate, and the discrete lag time were determined directly by the nonlinear regression model. For each forage, Fraction A was calculated as 100 – (B + C); similarly, the potential extent of disappearance was calculated as 100 – C. For all forages, the effective ruminal disappearance of DM and NDF was calculated as described by Ørskov and McDonald (1979)Go as A + B x (Kd/[Kd + Kp]), where Kd = disappearance rate and Kp = passage rate (0.025 ± 0.0054 h–1). However, calculations of effective ruminal disappearance for individual steers were based on the Kp determined in the same steer during the trial.

Rate of Passage

To calculate the ruminal passage rate of the basal diet for each steer, acid detergent insoluble ash was used as an internal marker. On the final day of the in situ trial, ruminal contents were evacuated manually before feeding (0 h) and 4 h after feeding. Total ruminal contents were weighed, mixed, and triplicate samples were dried under forced air at 50°C to a constant weight. Samples were stirred periodically to prevent molding. Alfalfa hay and the concentrate supplement from the basal diet were collected each day, composited, placed in paper bags, and dried to a constant weight as described previously. Dried rumen contents and diet samples were ground to pass a 1-mm screen via a Wiley mill, and concentrations of acid detergent insoluble ash in both the basal diet and ruminal contents were determined following digestion in acid detergent (Ankom Technology Corp.). Residual ash was determined for these ADF residues by combustion in a muffle furnace at 500°C for 8 h, followed by weighing. Hourly intake of acid detergent insoluble ash for each steer was obtained by totaling daily intake of acid detergent insoluble ash and dividing it by 24 h. The fractional rate of passage of acid detergent insoluble ash was calculated by dividing the mean acid detergent insoluble ash intake (g/h) by the mean ruminal mass (g) of this fraction (Waldo et al., 1972Go). For this study, the calculated mean rate of passage was 0.025 ± 0.0054 h–1 for the five experimental steers.

Statistics

Agronomic characteristics and the nutritive value of leaf, stem, and whole-plant crabgrass forages were analyzed as a randomized complete block design with field blocks (n = 4) as replications and seven harvest dates as the treatment effect. Leaf, stem, and whole-plant tissues were evaluated by independent ANOVA. The effect of sampling date was evaluated by single-df orthogonal contrasts for linear, quadratic, cubic, and quartic effects of time using the GLM procedures of SAS. Disappearance kinetics of DM and NDF for whole-plant crabgrass, as well as the alfalfa, orchardgrass, and bermudagrass hay controls were evaluated as a randomized complete block design with the five steers designated as blocks. Single-df orthogonal contrasts (PROC GLM) were used to evaluate the effects of sampling date on the disappearance kinetics of crabgrass, and to compare crabgrass with the control hays. Statistical significance was declared at P <0.05.


   Results and Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results and Discussion
Implications
 Literature Cited
 
Agronomic Characteristics of Crabgrass

Stem elongation had reached the three-node stage when sampling began on July 11 (Table 2Go). Although the average growth stage of crabgrass plants became more mature over time and reached the milk stage of seed development on the final harvest dates, there was considerable diversity within these swards. This was particularly evident during the August 15 and 22 sampling dates, when numerous immature tillers were observed that were released by late July and August rains (Table 1Go); therefore, the average growth stage on the final harvest dates included both fully mature and other less-developed tillers. The release of new tillers late in the sampling period also was reflected in the cubic (P = 0.032) and quadratic (P <0.001) effects observed for percentage of leaf blade that were caused, in part, by 6.6 and 6.9 percentage unit increases in leaf blade percent on the August 15 and 22 sampling dates, respectively, relative to that observed on August 8. The common crabgrass plants evaluated in this study contained relatively low percentages of leaf blade, which ranged from a high of 46.6% at the three-node stage of growth on July 11 to a minimum of only 28.4% when inflorescence was emerging on August 8. This observation suggests that any desirable quality characteristics and improved livestock performance observed for cattle consuming crabgrass must be associated heavily with the excellent nutritional value of stem tissue.


View this table:
[in this window]
[in a new window]
  		Table 2. Average growth stage, canopy height, available forage, and percentage of leaf blade in crabgrass forages sampled weekly near Prairie Grove, AR
 
Both canopy height (P <0.001) and available forage (P = 0.003) increased linearly over sampling dates, ranging from 28.4 to 47.0 cm and 3,117 to 4,634 kg of DM/ha, respectively. Dalrymple et al. (1999)Go reported that pure stands of Red River crabgrass have produced more than 14,000 kg of DM/ha of forage under intensive management with multiple harvests and may reach a height of 91 cm. However, this level of forage production was not obtained in the present study, where the maximum canopy height was only 47.0 cm, and a single-harvest system was used that did not consider potential contributions made by regrowth.

Nutritive Value of Crabgrass

Leaf Blade. Concentrations of most fiber components (NDF, ADF, hemicellulose, and ADL) in the leaf blade increased over sampling dates, but responses were not consistent across individual fiber components (Table 3Go). Concentrations of NDF increased with cubic (P = 0.034), quadratic (P = 0.002), and linear (P <0.001) effects of time, whereas ADF exhibited only quadratic (P <0.001) and linear (P = 0.002) effects. Hemicellulose concentrations exhibited the most complex response over sampling dates, increasing with quartic (P = 0.002), cubic (P = 0.031), and linear (P <0.001) effects. In contrast, concentrations of ADL increased in only a simple linear (P = 0.002) pattern over sampling dates. Despite both quadratic (P = 0.001) and linear (P = 0.048) effects of time, concentrations of cellulose generally were relatively static, exhibiting an overall range that was quite small (20.3 to 22.5%), and the concentration observed on July 11 differed from that on August 22 by only 0.3 percentage units. Tiller release following rainfall events likely contributed to the significant higher-order polynomial effects; however, the general pattern over time for most fiber components was one of small increases in concentration. The relatively stable fiber content during the 6-wk sampling period is a desirable nutritional characteristic. Unlike the responses observed for fiber components, concentrations of CP decreased in a linear (P <0.001) pattern over sampling dates, with no (P ≥ 0.13) higher-order polynomial effects. However, the overall range between July 11 and August 22 sampling dates was relatively narrow (19.6 to 23.8%) for a 6-wk time interval, further indicating that the nutritive value for crabgrass leaves is relatively stable over time.


View this table:
[in this window]
[in a new window]
  		Table 3. Concentrations of crude protein and fiber fractions of leaf-blade tissue for crabgrass forages
 
Stem. The fiber composition of stem tissue, which included any reproductive parts and leaf sheath, generally remained stable during the trial (Table 4Go). Concentrations of NDF and ADF increased, exhibiting both cubic (P ≤ 0.027) and linear (P ≤ 0.014) effects of time; however, the overall ranges for both NDF and ADF were narrow (7.2 and 4.7 percentage units), and the concentration of ADF on the initial sampling date differed by only 0.3 percentage units from that on August 22. Cellulose exhibited cubic (P = 0.049) and quadratic (P = 0.049) responses over sampling dates, but these responses likely had little biological significance; the overall range (26.4 to 29.2%) was extremely narrow and the concentration on the initial sampling date was actually greater numerically than that observed on the final harvest date. Unlike other fiber components, concentrations of hemicellulose and ADL increased in only a linear (P <0.001) relationship with sampling date, but differences between concentrations observed on the first and last sampling dates were again relatively small (3.9 and 0.87 percentage units, respectively).


View this table:
[in this window]
[in a new window]
  		Table 4. Concentrations of crude protein and fiber fractions of stem tissue for crabgrass foragesa
 
Several other observations concerning the fiber composition of these crabgrass forages were unusual compared with perennial warm-season forages. Concentrations of NDF and ADL were low, and did not exceed 64.2 and 3.39% at any time during the sampling period. Previous evaluations of stem tissue on comparable dates for perennial warm-season grasses, such as eastern gamagrass (Tripsacum dactyloides [L.] L.; Coblentz et al., 1998Go), switchgrass (Panicum virgatum L.; Griffin and Jung, 1983Go; Redfearn et al., 1999Go), and big bluestem (Andropogon gerardi Vitman; Griffin and Jung, 1983Go), have yielded substantially higher concentrations of these fractions. Although concentrations of CP in stem tissue decreased linearly (P = 0.002) over sampling dates, they remained exceptionally high (range = 15.1 to 19.6%) throughout the trial. By comparison, concentrations of CP in unfertilized stem tissue from big blue-stem and switchgrass ranged from 3.6 to 7.3% and 3.7 to 6.6%, respectively, when harvested between mid-June and late August in Pennsylvania (Griffin and Jung, 1983Go).

Whole-Plant Forage. As observed for individual leaf blade and stem tissues, concentrations of CP decreased linearly (P = 0.001) over sampling dates; however, they were never below 15.9% (Table 5Go). Concentrations of NDF, ADF, and cellulose in whole-plant tissue increased linearly (P ≤ 0.013) over sampling dates, but both quadratic (P = 0.006) and linear (P < 0.001) effects of time were observed for hemicellulose. Unlike other fiber components, a quartic effect (P = 0.034) was observed for concentrations of ADL; this effect was coupled with the linear (P < 0.001) effect that also was observed for all other response variables. Although concentrations of fiber components increased over time, these increases were relatively small in magnitude. For example, whole-plant concentrations of NDF ranged from 55.5 to only 61.9% over the seven sampling dates. These concentrations of NDF are lower than reported for many studies with perennial warm-season grasses grown throughout the southern United States, including dallisgrass (Paspulum dilatatum Poir.) harvested in Texas and Louisiana (ranges = 68.5 to 71.6% and 68.0 to 70.7%, respectively; Venuto et al., 2003Go); stargrass (Cynodon nlemfuensis Vanderyst), bahiagrass, and bermudagrass (ranges = 70.0 to 78.3, 72.5 to 78.0, and 71.9 to 79.6%, respectively; Johnson et al., 2001Go); and various studies (Mandebvu et al., 1998Go, 1999Go; Galdámez-Cabrera et al., 2003Go) with bermudagrass, in which concentrations of NDF ranged from 64.1 to 82.3%. In some cases, the difference between concentrations of NDF in whole-plant crabgrass and those reported for other perennial warm-season grasses was greater than 20 percentage units of NDF. This is ironic because crab-grass is likely to be considered an undesirable contaminant in many of these perennial warm-season grasses, especially bermudagrass. For the control hays evaluated in this study, the bermudagrass had excellent nutritional value, but the alfalfa and orchardgrass hays had only low or moderate nutritional value for these forages (Table 5Go).


View this table:
[in this window]
[in a new window]
  		Table 5. Concentrations of crude protein and fiber fractions for whole-plant crabgrass forages, and for alfalfa, common bermudagrass, and orchardgrass control hays that were evaluated simultaneously in situ
 
Regardless of plant tissue type, common crabgrass generally exhibited very stable quality traits over a 6-wk sampling period, which encompassed a broad range of maturity stages (Table 2Go). For whole-plant forage, concentrations of NDF, ADF, cellulose, and ADL increased by 5.7, 1.5, 1.3, and 0.46 percentage units between the July 11 and August 22 harvest dates. This is especially relevant within the context of finding an alternative forage for livestock with high nutrient demands for the southeastern United States. In contrast, sod-seeded oat (Avena sativa L.), wheat (Triticum aestivum L.), and rye (Secale cereale L.) exhibited respective increases of 22.1, 18.5, and 23.7 percentage units for NDF, and 15.2, 11.2, and 24.4 percentage units for ADF when harvested between March 24 and May 26 in northern Arkansas (Coblentz et al., 2000Go). Similarly, Hoffman et al. (1993)Go reported substantial increases in NDF and ADF for perennial cool-season grasses harvested between the second node and full inflorescence stages of growth. Specifically, perennial ryegrass (Lolium perenne L.) exhibited increases of 17.0 and 14.6 percentage units of NDF and ADF, respectively, during this time interval. Similarly, Coblentz et al. (1998)Go reported that NDF and ADF increased by 8.6 and 9.5 percentage units, respectively, for eastern gamagrass harvested at boot stage and at physiological maturity in Kansas. Eastern gamagrass is a native, perennial bunch-type grass that fixes carbon via the C4 photosynthetic pathway (Waller and Lewis, 1979Go). Although some of the stability with respect to nutritive value demonstrated by common crabgrass may be explained on the basis of continuing development of new, less mature tillers throughout the sampling period, the limited changes in fiber composition over an extended 6-wk sampling interval is encouraging.

Ruminal Disappearance Kinetics of DM

Fractions A and B. For ruminal disappearance of DM from crabgrass forages, Fraction A declined with quartic (P = 0.025), quadratic (P = 0.003), and linear (P = 0.003) effects over sampling dates (Table 6Go). These changes are likely of little importance biologically because Fraction A was very consistent across sampling dates, ranging narrowly from 33.0 to 33.9% over the first five sampling dates, and from 31.3 to 33.9% over the entire study. Similarly, Fraction B decreased, exhibiting quartic (P = 0.001), quadratic (P < 0.001), and linear (P < 0.001) effects of time, but, on a practical basis, varied little with sampling date, exhibiting a difference of only 2.5 percentage units between July 11 and August 22.


View this table:
[in this window]
[in a new window]
  		Table 6. In situ disappearance kinetics of dry matter for common crabgrass sampled on weekly intervals near Prairie Grove, AR, and compared with alfalfa, bermudagrass, and orchardgrass hay controls
 
For the alfalfa hay control, Fraction A was slightly less than reported previously (Hoffman et al., 1993Go; Coblentz et al., 1998Go), in which estimates ranged from 32.5 to 46.7% and decreased with maturity (Hoffman et al., 1993Go). In the present study, the mean Fraction A for crabgrass sampled over seven dates was greater (P < 0.001) than observed for the alfalfa hay, but the magnitude of this difference was very small (32.9 vs. 29.4%). Fraction B, which degrades at a measurable rate, agreed closely with previous estimates for alfalfa (Hoffman et al., 1993Go; Coblentz et al., 1998Go), but was 12.8 to 17.5 percentage units smaller (P < 0.001) than observed for the crabgrass forages.

For the bermudagrass hay, Fraction A was similar to an estimate by Galdámez-Cabrera et al. (2003)Go for common bermudagrass harvested in late May in northwestern Arkansas, but was substantially greater than estimates by Mandebvu et al. (1999)Go for Tifton 85 and Coastal bermudagrasses produced in southern Georgia. Fraction A was smaller by 4.7 to 7.3 and 10.2 to 12.8 percentage units in the bermudagrass (P < 0.001) and orchardgrass (P < 0.001) hays, respectively, than in crabgrass forages. In contrast with the alfalfa hay, Fraction B for both the bermudagrass and orchardgrass control hays was greater (P < 0.001) by 3.3 to 11.7 percentage units than observed for crabgrass forages.

Potential Extent. Although the potential extent of ruminal DM disappearance for crabgrass forages decreased with quartic (P = 0.009), quadratic (P < 0.001), and linear (P < 0.001) effects of time (Table 6Go), the potential extent remained exceptionally high (≥ 83.2%) on all dates, and the total decrease with maturity was very small (range = 4.8 percentage units). The potential ruminal DM disappearance for the bermudagrass hay was very high relative to other work, exceeding estimates made by Galdámez-Cabrera et al. (2003)Go for common bermudagrass harvested in late May and August in northwest Arkansas by 3.5 to 10.8 percentage units, and far exceeding estimates made by Mandebvu et al. (1999)Go for Tifton 85 and Coastal bermudagrass grown in southern Georgia. Despite the exceptional ruminal availability of the bermudagrass hay evaluated in the present study, the bermudagrass did not differ (P = 0.64) from crabgrass forages. In contrast, the potential ruminal availability for crabgrass forages exceeded (P < 0.001) that of the orchardgrass and alfalfa hay controls, and this differential was far greater for alfalfa (16.2 to 21.0 percentage units) than for orchardgrass (0.1 to 4.9 percentage units). This finding likely can be explained on the basis of the high concentration of ADL in this alfalfa hay (7.43%) compared with the relatively low concentrations of ADL measured in orchardgrass (2.73%) and whole-plant crabgrass sampled on all dates (range = 1.89 to 2.90%; Table 5Go). Past estimates of potential extent of DM disappearance for alfalfa forages have seldom exceeded 80% when the forage reaches early bloom (Balde et al., 1993Go; Hoffman et al., 1993Go; Coblentz et al., 1998Go), and can range between 65.9 and 74.7% when maturity reaches mid or full bloom (Balde et al., 1993Go; Hoffman et al., 1993Go).

Lag Time. For crabgrass, the lag time required for microbial attachment and initiation of digestion ranged from 1.36 to 2.41 h and changed in a quartic (P = 0.030) pattern over sampling dates (Table 6Go). Estimates of lag time were not fitted (P ≥ 0.42) by other polynomial effects of sampling date. Lag times for crabgrass did not differ (P = 0.43) from that observed for alfalfa, but were shorter than observed for bermudagrass (P = 0.001) and orchardgrass (P < 0.001).

Ruminal Disappearance Rate. To the best of our knowledge, ruminal disappearance rates of DM for crabgrass have not been determined previously. Our estimates of disappearance rate for crabgrass (overall mean = 0.078 h–1; Table 6Go) were more rapid than reported for other warm-season perennial grasses, including eastern gamagrass (0.035 to 0.048 h–1; Coblentz et al., 1998Go), common bermudagrass fertilized with 0 to 168 kg of N/ha and harvested in late May or mid August (mean values = 0.033 and 0.036 h–1, respectively; Galdámez-Cabrera et al., 2003Go), and Tifton 85 and Coastal bermudagrass (0.028 h–1; Mandebvu et al., 1999Go). It is assumed commonly that the suitability of warm-season perennial grasses for use within diets of livestock with high nutrient demands, such as dairy cows, is limited by high concentrations of fiber components and slow ruminal disappearance rates. These factors are assumed frequently to work together to limit DMI with forage-based diets. In this study, the overall mean disappearance rate for crabgrass exceeded (P < 0.001) that of our high-quality bermudagrass hay control by 44%; however, based on other estimates of ruminal DM disappearance reported for bermudagrass (Mandebvu et al., 1999Go; Galdámez-Cabrera et al., 2003Go), it is possible that crabgrass could disappear from the rumen at rates approaching twice those of more typical bermudagrass forages.

Although the crabgrass forages evaluated in this study disappeared at a much faster rate than bermudagrass, they disappeared at about half the rate of the alfalfa hay control (P < 0.001). Other estimates of DM disappearance rate for alfalfa (0.096 h–1, Balde et al., 1993Go; 0.13 to 0.16 h–1, Hoffman et al., 1993Go; 0.152 h–1, Coblentz et al., 1998Go) compare closely to the rate observed for alfalfa in this study. In contrast, the ruminal disappearance rates for crabgrass generally exceeded those reported for sod-seeded cereal grains harvested during boot and heading stages in northern Arkansas (Coblentz et al., 2000Go) and perennial cool-season grasses harvested at boot and heading stages in Wisconsin (Hoffman et al., 1993Go). In this study, disappearance rates for crabgrass also exceeded (P = 0.002) those of the orchardgrass hay by approximately 30%, further indicating that crabgrass may offer considerable potential as an alternative to other summer forages for cattle.

Effective Ruminal Disappearance. The effective ruminal disappearance for crabgrass ranged from 69.3 to 75.4%, and it decreased in cubic (P = 0.001), quadratic (P = 0.038), and linear (P < 0.001) patterns over sampling dates (Table 6Go). Estimates of effective ruminal DM disappearance were greater (P < 0.001) for crab-grass than observed for alfalfa, bermudagrass, and orchardgrass hays. In addition, the overall mean (72.3%) for crabgrass approached estimates made for vegetative sod-seeded cereal grains in northern Arkansas (77.8 to 80.0%; Coblentz et al., 2000Go). Although estimates of effective ruminal DM disappearance have not been reported previously for crabgrass, Bosworth et al. (1980)Go reported in vitro DM digestibilities of 79, 72, and 63% for crabgrass at the vegetative, booting, and heading stages of growth, respectively.

Disappearance Kinetics of NDF

Fractions A and B. For ruminal disappearance of NDF from crabgrass forages, Fraction A changed in cubic (P = 0.005) and quadratic (P = 0.003) patterns with harvest dates (Table 7Go); however, only a very small fraction of the total forage NDF (≤7.5%) was found in Fraction A. Theoretically, NDF comprises cell wall components (Van Soest, 1982Go) that should not be soluble during a 0.33-h soak in tepid water followed by machine rinsing in cold water. The small portions of NDF that were partitioned into Fraction A may be associated in part with the direct loss of small particles from the bags, rather than with the solubilization of cell wall components in water. Similarly, small percentages of the total forage NDF pool have been associated with Fraction A in several other studies (Coblentz et al., 1998Go, 2000Go; Galdámez-Cabrera et al., 2003Go). Fraction B for crabgrass decreased from 76.6 to 69.9% over harvest dates, exhibiting quartic (P = 0.001), cubic (P = 0.009), quadratic (P < 0.001), and linear (P < 0.001) effects of time. Overall, Fraction B for the seven crabgrass forages did not differ from either the bermudagrass (P = 0.51) or orchardgrass (P = 0.34) hay controls, but comprised nearly twice as much (P < 0.001) of the total NDF pool as observed for alfalfa.


View this table:
[in this window]
[in a new window]
  		Table 7. In situ disappearance kinetics of neutral detergent fiber for common crabgrass sampled on weekly intervals, and compared with alfalfa, bermudagrass, and orchardgrass hay controls
 
Potential Extent. Over the seven sampling dates, the mean potential extent of NDF disappearance for crabgrass forages was 78.4%, and weekly estimates varied by a total range of only 5.7 percentage units during the entire study. Overall, the potential extent of NDF disappearance for crabgrass was slightly less than that observed for both the bermudagrass (P < 0.001) and orchardgrass (P = 0.003) hays, but all crabgrass forages had a far greater (68.1 to 80.6%; P < 0.001) potential extent of NDF disappearance than alfalfa hay. The low potential extent of disappearance (45.4%) observed in this study compares closely with previous reports for blooming alfalfa (Hoffman et al., 1993Go; Coblentz et al., 1998Go) and reflects the highly lignified nature of alfalfa stem. The potential extent of disappearance for the common bermudagrass evaluated in this study was greater than observed in several other in situ (Mandebvu et al., 1999Go; Galdámez-Cabrera et al., 2003Go) and in vitro studies (Mertens and Lofton, 1980; Mandebvu et al., 1998Go). In these studies, estimates of potential extent ranged from approximately 78% for Tifton 85 bermudagrass harvested after 3.5 wk of growth (Mandebvu et al., 1998Go) to approximately 45% for Coastal bermudagrass harvested after 7 wk of growth (Mandebvu et al., 1999Go). Therefore, the potential ruminal availability of NDF in crabgrass likely compares very favorably with most bermudagrass forages.

Lag Time. Sampling date had no effect (P ≥ 0.15) on lag time for crabgrass forages. When compared with the hay controls, lag times for crabgrass did not differ (P = 0.11) from alfalfa, but they were shorter (P < 0.001) by 0.76 to 1.39 h than values observed for bermudagrass, and by 1.84 to 2.47 h compared with orchardgrass.

Disappearance Rate. Whole-plant crabgrass exhibited cubic (P = 0.002) and linear (P = 0.002) decreases in ruminal NDF disappearance rate; however, the overall range (0.069 to 0.086 h–1) was relatively narrow, and the estimate made on the final sampling date differed numerically by 0.002 h–1 from that made on the initial sampling date. The mean disappearance rate for crabgrass sampled over all dates (0.078 h–1) was 37 and 32% faster (P < 0.001) than observed for the bermudagrass and orchardgrass control hays, respectively. In addition, disappearance rates for these crabgrass forages were much faster generally than observed for other warm-season grasses in similar kinetic evaluations of fiber disappearance. Estimates for eastern gamagrass (0.032 to 0.056 h–1; Coblentz et al., 1998Go), un-grazed (0.032 to 0.052 h–1) and grazed (0.037 to 0.041 h–1) fall-stockpiled bermudagrass (Scarbrough et al., 2001Go), common bermudagrass (0.025 to 0.035 h–1; Galdámez-Cabrera et al., 2003Go), Coastal (0.027 h–1) and Tifton 85 (0.031 h–1) bermudagrass (Mandebvu et al., 1999Go), normal and brown-midrib sorghum-sudangrass (Sorghum bicolor [L.] Monech) hays (0.063 to 0.066 h–1; Fritz et al., 1988Go) were slower than those observed for the crabgrass forages in this study. This is particularly relevant in the southeastern United States, where forage alternatives to bermudagrass and other perennial warm-season grasses are critical to improving the performance of dairy and beef cattle with high nutrient demands.

Effective Disappearance. Effective ruminal disappearance of NDF from crabgrass forages declined cubically (P < 0.001), quadratically (P < 0.001), and linearly (P < 0.001) over sampling dates, but the magnitude of this decline was relatively small. The overall mean disappearance for the seven crabgrass forages was 60.6% of the total NDF pool, which was greater (P ≤ 0.004) than that observed for any of the control hays, although the practical difference between crabgrass forages and the bermudagrass control was only marginal. It should be emphasized that the bermudagrass hay evaluated as a control in this study was of exceptional quality, exhibiting characteristics of nutritive value and disappearance kinetics that are considerably superior to similar evaluations for many other bermudagrass samples. Furthermore, the passage rate of the basal diet (0.025 ± 0.005 h–1) was somewhat slow relative to rates of passage for high-producing ruminants, such as dairy cows, and incorporation of this relatively slow passage rate into calculations of effective ruminal disappearance will mask, rather than accentuate, differences between these two forages.


   Implications
Top
 Abstract
 Introduction
 Materials and Methods
 Results and Discussion
 Implications
Literature Cited
 
Based on our results, crabgrass offers a clear advantage over perennial warm-season grasses, such as bermudagrass, by offering lower concentrations of fiber components and more rapid rates of ruminal degradation. These traits should improve the potential for forage intake and subsequent livestock performance during the summer months in the southeastern United States. The nutritional value of the stem tissue seems to contribute heavily to these observations. More importantly, the magnitude of changes in various nutritional and kinetic indices was limited over an extended 6-wk sampling interval, thereby indicating that considerable flexibility may exist with respect to management and utilization. For ruminant livestock with high nutrient demands, common crabgrass seems to offer promise as an alternative to perennial warm-season grasses during the summer months throughout the southeastern United States.


   Footnotes
 
1 Contribution of the Arkansas Agric. Exp. Stn. Back

3 Current address: North Carolina State Mountain Res. Stn., Waynesville 28786. Back

4 Current address: Northwestern Oklahoma State Univ., Alva 73717. Back

2 Correspondence: B107B AFLS (phone: 479-575-7914; fax: 479-575-7294; e-mail: coblentz{at}uark.edu).

Received for publication December 6, 2004. Accepted for publication February 4, 2005.


   Literature Cited
Top
 Abstract
 Introduction
 Materials and Methods
 Results and Discussion
 Implications
 Literature Cited
 


Andrae, J. 2002. Crabgrass: Friend or foe? Georgia Cattleman. Available: http://commodities.caes.uga.edu/fieldcrops/forages/GA_cat_Arc/2002/Aug02.pdf. Accessed Feb. 21, 2005.

Balde, A. T., J. H. Vandersall, R. A. Erdman, J. B. Reeves, III, and B. P. Glenn. 1993. Effect of stage of maturity of alfalfa and orchardgrass on in situ dry matter and crude protein degradability and amino acid composition. Anim. Feed Sci. Technol. 44:29–43.

Bosworth, S. C., C. S. Hoveland, G. A. Buchanan, and W. B. Anthony. 1980. Forage quality of selected warm-season weed species. Agron. J. 72:1050–1054.[Abstract/Free Full Text]

Coblentz, W. K., K. P. Coffey, J. E. Turner, D. A. Scarbrough, J. S. Weyers, K. F. Harrison, Z. B. Johnson, L. B. Daniels, C. F. Rosenkrans, Jr., D. W. Kellogg, and D. S. Hubbell, III. 2000. Effect of maturity on degradation kinetics of sod-seeded cereal grain forage grown in northern Arkansas. J. Dairy Sci. 83:2499–2511.[Abstract]

Coblentz, W. K., J. O. Fritz, R. C. Cochran, W. L. Rooney, and K. K. Bolsen. 1997. Protein degradation in response to spontaneous heating in alfalfa hay by in situ and ficin methods. J. Dairy Sci. 80:700–713.[Abstract/Free Full Text]

Coblentz, W. K., J. O. Fritz, W. H. Fick, R. C. Cochran, and J. E. Shirley. 1998. In situ dry matter, nitrogen, and fiber degradation of alfalfa, red clover, and eastern gamagrass at four maturities. J. Dairy Sci. 81:150–161.[Abstract]

Dalrymple, R. L., R. Mitchell, B. Flatt, W. Dobbs, S. Ingram, and S. W. Coleman. 1999. Crabgrass for Forage: Management from the 1990s. #NF-FO-99–18. The Samuel Roberts Noble Found. Agric. Div., Ardmore, OK.

Fritz, J. O., K. J. Moore, and E. H. Jaster. 1988. In situ digestion kinetics and ruminal turnover rates of normal and brown midrib mutant sorghum x sudangrass hays fed to nonlactating Holstein cows. J. Dairy Sci. 71:3345–3351.

Galdámez-Cabrera, N. W., K. P. Coffey, W. K. Coblentz, J. E. Turner, D. A. Scarbrough, Z. B. Johnson, J. L. Gunsaulis, M. B. Daniels, and D. H. Hellwig. 2003. In situ ruminal degradation of dry matter and fiber from bermudagrass fertilized with different nitrogen rates and harvested on two dates. Anim. Feed Sci. Technol. 105:185–198.

Griffin, J. L., and G. A. Jung. 1983. Leaf and stem forage quality of big bluestem and switchgrass. Agron. J. 75:723–726.[Abstract/Free Full Text]

Hoffman, P. C., S. J. Sievert, R. D. Shaver, D. A. Welch, and D. K. Combs. 1993. In situ dry matter, protein, and fiber degradation of perennial forages. J. Dairy Sci. 76:2632–2643.[Abstract]

Johnson, C. R., B. A. Reiling, P. Mislevy, and M. B. Hall. 2001. Effects of nitrogen fertilization and harvest date on yield, digestibility, fiber, and protein fractions of tropical grasses. J. Anim. Sci. 79:2439–2448.[Abstract/Free Full Text]

Mandebvu, P., J. W. West, R. N. Gates, and G. M. Hill. 1998. In vitro digestion kinetics of neutral detergent fiber extracted from Tifton 85 and Coastal bermudagrasses. Anim. Feed Sci. Technol. 73:263–269.

Mandebvu, P., J. W. West, G. M. Hill, R. N. Gates, R. D. Hatfield, B. G. Mullinix, A. H. Parks, and A. B. Caudle. 1999. Comparison of Tifton 85 and Coastal bermudagrass for yield, nutrient traits, intake, and digestion by growing steers. J. Anim. Sci. 77:1572–1586.[Abstract/Free Full Text]

Mertens, D. R., and J. R. Loften. 1980. The effect of starch on forage fiber digestion kinetics in vitro. J. Dairy Sci. 63:1437–1446.

Ørskov, E. R., and I. McDonald. 1979. The estimation of protein degradability in the rumen from incubation measurements weighted according to rate of passage. J. Agric. Sci. (Camb.) 92:499–503.

Redfearn, D. D., K. J. Moore, K. P. Vogel, S. S. Waller, and R. B. Mitchell. 1999. Fiber digestion dynamics of sward components within switchgrass populations. Crop. Sci. 39:784–789.[Abstract/Free Full Text]

Scarbrough, D. A., W. K. Coblentz, K. P. Coffey, J. E. Turner, G. V. Davis, D. W. Kellogg, and D. L. Hellwig. 2001. Effects of calendar date and summer management on the in situ dry matter and fiber degradation of stockpiled forage from bermudagrass pastures. J. Anim. Sci. 79:3158–3169.[Abstract/Free Full Text]

Vanzant, E. S., R. C. Cochran, and E. C. Titgemeyer. 1998. Standardization of in situ techniques for ruminant feedstuff evaluation. J. Anim. Sci. 76:2717–2729.[Abstract/Free Full Text]

Vanzant, E. S., R. C. Cochran, E. C. Titgemeyer, S. D. Stafford, K. C. Olson, D. E. Johnson, and G. St. Jean. 1996. In vivo and in situ measurements of forage protein degradation in beef cattle. J. Anim. Sci. 74:2773–2784.[Abstract]

Van Soest, P. J. 1982. Nutritional Ecology of the Ruminant. Cornell Univ. Press, Ithaca, NY.

Venuto, B. C., B. L. Burson, M. A. Hussey, D. D. Redfearn, W. E. Wyatt, and L. P. Brown. 2003. Forage yield, nutritive value, and grazing tolerance of dallisgrass biotypes. Crop. Sci. 43:295–301.[Abstract/Free Full Text]

Waldo, D. R., L. W. Smith, and E. L. Cox. 1972. Model of cellulose disappearance from the rumen. J. Dairy Sci. 55:125–129.

Waller, S. S., and J. K. Lewis. 1979. Occurrence of C3 and C4 photosynthetic pathways in North American grasses. J. Range Manage. 32:12–28.


This article has been cited by other articles:


Home page
 J DAIRY SCIHome page
W. K. Coblentz and P. C. Hoffman
Effects of bale moisture and bale diameter on spontaneous heating, dry matter recovery, in vitro true digestibility, and in situ disappearance kinetics of alfalfa-orchardgrass hays
J Dairy Sci, June 1, 2009; 92(6): 2853 - 2874.
[Abstract] [Full Text] [PDF]

Home page
 J DAIRY SCIHome page
W. K. Coblentz and P. C. Hoffman
Effects of spontaneous heating on fiber composition, fiber digestibility, and in situ disappearance kinetics of neutral detergent fiber for alfalfa-orchardgrass hays
J Dairy Sci, June 1, 2009; 92(6): 2875 - 2895.
[Abstract] [Full Text] [PDF]

Home page
 J ANIM SCIHome page
P. A. Beck, S. Hutchison, C. B. Stewart, J. D. Shockey, and S. A. Gunter
Effect of crabgrass (Digitaria ciliaris) hay harvest interval on forage quality and performance of growing calves fed mixed diets
J Anim Sci, February 1, 2007; 85(2): 527 - 535.
[Abstract] [Full Text] [PDF]

Home page
 J ANIM SCIHome page
R. K. Ogden, W. K. Coblentz, K. P. Coffey, J. E. Turner, D. A. Scarbrough, J. A. Jennings, and M. D. Richardson
Ruminal in situ disappearance kinetics of nitrogen and neutral detergent insoluble nitrogen from common crabgrass forages sampled on seven dates in northern Arkansas
J Anim Sci, March 1, 2006; 84(3): 669 - 677.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ogden, R. K.
Right arrow Articles by Richardson, M. D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ogden, R. K.
Right arrow Articles by Richardson, M. D.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS