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FORAGE & GRAZING LANDS

Stockpiled Annual Ryegrass for Winter Forage in the Lower Midwestern USA

^a Dep. of Agronomy, Plant Sci. Unit, Univ. of Missouri, Columbia, MO 65211
^b Animal Sci. Unit, Univ. of Missouri, Columbia, MO 65211
^c Southwest Missouri Agric. Res. and Education Center, Mt. Vernon, MO 65712

^* Corresponding author (kallenbachr{at}missouri.edu)

	ABSTRACT

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Livestock operations, particularly pasture-based dairies in the lower Midwest, are interested in stockpiling annual ryegrass (Lolium multiflorum Lam.) as a source of high-quality winter forage. Almost no information exists about stockpiling annual ryegrass in this region. Our objective was to determine the yield and forage quality of stockpiled annual ryegrass compared with cereal rye during winter in the lower Midwest. ‘Barmultra’ and ‘Marshall’ annual ryegrass were evaluated at two locations (Columbia and Mt. Vernon, MO) during the winters of 1998-1999 (Year 1) and 1999-2000 (Year 2). ‘Forage Master’ cereal rye (Secale cereale L.) was included as a comparison. Uncut strips (subplots) were harvested monthly from mid-December through mid-March each year. Stockpiled annual ryegrass yields ranged from 825 to 2356 kg ha^-1, with Marshall yielding more than Barmultra on all but one harvest date during the 2 yr. Forage quality of stockpiled annual ryegrass typically declined from mid-December through mid-February, with a larger decline in a normal winter (Year 1) than in a mild winter (Year 2). Although forage quality tended to decline during winter, acid detergent fiber (ADF) never exceeded 252 g kg^-1, and neutral detergent fiber (NDF) never exceeded 455 g kg^-1. This suggests that stockpiled annual ryegrass could be used in the lower Midwest as a source of high-quality winter forage for grazing livestock.

Abbreviations: ADF, acid detergent fiber • CP, crude protein • NDF, neutral detergent fiber • NIR, near-infrared reflectance

	INTRODUCTION

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
THE NUMBER OF PASTURE-BASED DAIRY OPERATIONS in the lower Midwest has increased four-fold since 1998 (Pierce et al., 2002). These operations seek to maximize profitability by minimizing input costs while maintaining economic levels of milk production (Elbehri and Ford, 1995; Hanson et al., 1998). One characteristic common to pasture-based dairy operations in this region is their reliance on high quality pasture instead of hay or silage. Their pastures supply inexpensive forage to their lactating cows, which reduces feed costs by 30 to 50% compared with conventional stored-forage systems (Parker et al., 1992; Hanson et al., 1998).

In addition, many beef producers in this region are considering retained ownership of stocker calves through the backgrounding stage as a means to capture additional value (Davis et al., 1998; Lawrence, 2000). Like pasture-based dairy operations, these producers desire high-quality forage for their livestock. Recent economic analyses show that beef production from high-quality pastures costs one-half to one-fourth as much as the same production using stored forages (Bishop-Hurley and Kallenbach, 2001).

While pasture systems offer an inexpensive source of high quality forage, forage supply is often unreliable. Pasture growth, and thus forage supply, fluctuates throughout the year because of variable growing conditions (Fales et al., 1993; Matches and Burns, 1995). This creates an uneven forage supply and an intermittent failure of the pasture system to meet livestock requirements (Fales et al., 1993; Matches and Burns, 1995). In the lower Midwest, the longest period of inadequate forage supply is from mid-December through mid-March (Matches and Burns, 1995; Kallenbach et al., 2001) and livestock producers in this region are searching for high quality forage for winter grazing.

One forage species attracting the attention of livestock producers in the lower Midwest is annual ryegrass. Producers establish annual ryegrass in the late summer, then allow it to accumulate growth for deferred or stockpile grazing in the winter. For pasture-based dairy and beef stocker operations in the lower Midwest, stockpiled annual ryegrass has become a popular forage for winter grazing.

Despite its popularity, stockpiling annual ryegrass has not been widely researched in the lower Midwest. However, there are several reasons why its potential should be explored for this region. One reason is that annual ryegrass grows rapidly during autumn. Autumn growth rates in the southern USA have reached 49 kg ha^-1 d^-1 (Mooso et al., 1990; Cuomo et al., 1999); similar growth rates may be possible further north. Although the autumn growing season in the lower Midwest is shorter than in the southern USA, annual ryegrass might still accumulate 3000 kg ha^-1 for deferred grazing in winter.

A second reason for exploring annual ryegrass for winter grazing in the lower Midwest is that it continues to grow after the first killing frost in autumn. Annual ryegrass lacks true dormancy, so it can resume growth during warm periods in late autumn or early winter, which maximizes forage accumulation (Keatinge et al., 1980; Hill and Pearson, 1985; Hoveland et al., 1991). Cold-tolerant cultivars can even grow when average daily temperatures are <6°C (Keatinge et al., 1980; Cherney and Robinson, 1985).

A third reason for exploring annual ryegrass relates to forage quality. During vegetative growth, crude protein (CP) concentrations in annual ryegrass often exceed 200 g kg^-1, while ADF concentrations remain <220 g kg^-1 and NDF concentrations are <400 g kg^-1 (Mooso et al., 1990; Lippke, 1995). The result of a low fiber concentration is a highly digestible forage that supports milk yields of 34 kg per head per day or more (McCormick et al., 2001) and stocker calf gains of 0.5 to 1.5 kg per head per day (Riewe et al., 1963; Hoveland et al., 1991; Sladden and Bransby, 1992).

In the past, annual ryegrass has been used far less than cereal rye for high-quality winter pastures in climates where minimum temperatures are <-15°C (Evers, 1995; Rao and Horn, 1995). The reasons most often cited for its poor adoption relate to annual ryegrass's lack of winter hardiness and its rapid decline in forage quality during winter (Balasko et al., 1995). However, more cold-tolerant cultivars have been developed within the last 20 yr, and they should be investigated as a source of forage for deferred winter grazing in the lower Midwest (Balasko et al., 1995; Nelson, 1995).

We hypothesize that livestock producers in the lower Midwest could stockpile a cold-tolerant cultivar of annual ryegrass and use it as a source of forage for deferred grazing in winter. Our objective was to determine the yield and forage quality of stockpiled annual ryegrass compared with cereal rye during winter in the lower Midwest.

	MATERIALS AND METHODS

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Three forage entries, including two annual ryegrass cultivars and cereal rye, were evaluated at two locations during the winters of 1998-1999 and 1999-2000. The annual ryegrass cultivars were Barmultra and Marshall and both are considered cold-tolerant (Arnold et al., 1981; Balasko et al., 1995; Nelson, 1995). The cereal rye was Forage Master, a cultivar widely marketed as a "forage type" in the lower midwestern USA.

The experimental sites were the Bradford Research Center, near Columbia, MO (38°57' N 92°20' W), and the Southwest Missouri Research and Education Center, near Mt. Vernon, MO (37°06' N 93°49' W). The soil type at Columbia is a Mexico silt loam (fine, smectitic, mesic Aeric Vertic Epiaqualfs) and the average air temperature from December through March is 1.0°C. The soil type at Mt. Vernon is a Medoc silt loam (fine, mixed, active, thermic Aeric Albaqualfs) and the average air temperature from December through March is 2.5°C.

For the 1998-1999 season (Year 1), entries were planted on 6 September at Columbia and on 4 September at Mt. Vernon. For the 1999-2000 season (Year 2), entries were planted on 25 August at Columbia and 30 August at Mt. Vernon. A new plot area was used at each location each year. Seeding rates (pure live seed) were 34 kg ha^-1 for annual ryegrass and 140 kg ha^-1 for cereal rye. Plots were seeded by broadcasting onto a conventionally prepared seedbed. Annual ryegrass seeds were covered by rolling with a cultipacker. Cereal rye plots were hand-raked to bury seeds 3 cm, and then rolled with a cultipacker. Plots received 84 kg ha^-1 of N fertilizer as ammonium nitrate the day before planting. Phosphorus, K, and lime were applied at each location 90 d before planting. These amendments were applied to provide 30 kg ha^-1 of Bray I P, 275 kg ha^-1 of K, and to adjust soil pH to 6.3 at each location. Weed and insect pests were minimal and no pesticides were applied.

In Year 1, main plots in Columbia were 6.0 by 13.7 m and at Mt. Vernon they were 6.0 by 10.6 m. In Year 2, main plots at both locations were 6.0 by 9.1 m. Main plots were split into four subplots, each subplot being 1.5 m wide. Unharvested forage from a single subplot within each main plot was harvested on a monthly basis from mid-December through mid-March. For Year 1, the harvest dates were 14 December, 20 January, 15 February, and 15 March at Columbia and 17 December, 14 January, 16 February, and 22 March at Mt. Vernon. For Year 2, the harvest dates were 14 December, 10 January, 14 February, and 13 March at Columbia and 17 December, 14 January, 15 February, and 15 March at Mt. Vernon. Hereafter, these harvest dates will be referred to as the December, January, February, or March harvests.

Within each subplot, forage was harvested from a 0.91- by 10.7-m strip at Columbia and a 0.81- by 7.6-m strip at Mt. Vernon in Year 1, while in Year 2 forage was harvested from a 0.91- by 7.6-m strip at Columbia and a 0.81- by 7.6-m strip at Mt. Vernon. All forage was harvested using a flail-type mower set to leave a 7-cm stubble. The fresh mass of each strip was recorded and a 350- (±50) g subsample was dried at 50°C for 96 h to determine dry matter. After drying, subsamples were ground to pass a 5-mm screen, and then reground to pass a 1-mm screen. Ground samples were retained for forage quality analyses.

Forage Quality Analyses
Crude protein, ADF, and NDF were determined using near-infrared reflectance (NIR) spectroscopy for all samples. The NIR spectrophotometer was a Pacific Scientific 6250 scanning monochromator (NIRSystems, Silver Spring, MD)¹ operating with software developed by Infrasoft International (Port Matilda, PA). The spectrophotometer was calibrated for CP, ADF, and NDF by regressing chemically-derived data against spectral data using modified partial least squares regression (Shenk and Westerhaus, 1991). The NIR calibration and validation statistics are presented in Table 1.

Statistical Design and Analysis
Each treatment was replicated three times in a randomized complete block design in a split-split-split plot arrangement with forage entries as main plots, locations as subplots, years as sub-subplots, and harvest dates with years as sub-sub-subplots. Analysis of variance was conducted on forage entries, locations, years, harvest dates within years, and all possible interactions using the model outlined by Steel and Torrie (1980). The General Linear Model (PROC GLM) function of the Statistical Analysis Systems software was used to compute the terms in the model (SAS Institute Inc., Cary, NC). Main effects and all interactions were considered significant when P < 0.05.

	RESULTS AND DISCUSSION

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Forage Yield
Forage yield varied significantly by entry, location, year, and harvest date. Interactions between entries and locations, and the three and four-way interactions with locations were not significant. Thus, data were pooled across locations within years. However, because of significant interactions between entries, years, and harvest dates, these results are discussed separately.

In December of Year 1, Marshall yielded 2356 kg ha^-1, which was 499 and 1724 kg ha^-1 more than Barmultra and cereal rye, respectively (Fig. 1). These yields compare favorably to those reported for the southern USA in early winter (Mooso et al., 1990; Cuomo et al., 1999). However, below-average temperatures (Table 2) in early January reduced yields at the next harvest (Fig. 1). In January, Marshall showed a 33% yield loss compared with December, Barmultra a 23% loss, and cereal rye a 49% loss. After that, Marshall's forage yield remained constant from January to February, but decreased again between February and March by 22%. In contrast, Barmultra had stable yields from January to March (Fig. 1). Between January and March, cereal rye constantly accumulated more forage, producing an additional 1102 kg ha^-1 during this period.

View larger version (19K): [in this window] [in a new window]   Fig. 1. Stockpiled forage yield of ‘Barmultra’ and ‘Marshall’ annual ryegrass and cereal rye, harvested monthly during the winters of 1998-1999 (Year 1) and 1999-2000 (Year 2). Data are pooled across two locations (Columbia and Mt. Vernon, MO) within years. Bars indicate standard errors; however, some error bars are smaller than the symbol and may not be visible.

Variable climatic conditions played a major role in the differences in forage accumulation patterns between years. Air temperatures and rainfall in the autumn and winter of Year 1 were closer to historic averages than in Year 2. In Year 1, the upper 10 cm of Barmultra and Marshall leaves showed visible signs of freeze damage (brown leaf tips) following a cold spell in early January. Other researchers have noted the sensitivity of annual ryegrass leaves to cold weather (Hides, 1979; Creamer et al., 1997). Most of this damaged tissue did not decay immediately, but remained on the plant until late February of Year 1. Once milder temperatures returned in late February, the damaged material began to decay at a faster rate than new growth was accumulating, especially for Marshall. In contrast, Year 2 was drier but warmer than average (Table 2). In Year 2, there was no noticeable freeze damage, and this likely led to the substantial late-winter growth for all entries.

Cereal rye also had variable yields between years, producing more than twice as much forage in Year 2 as in Year 1. Although cereal rye is usually easy to establish (Rao and Horn, 1995), it is sensitive to temperatures >25°C during germination (Nuttonson, 1958). For the first 5 d after planting in Year 1, average daily air temperatures were 29°C, which was 9°C above normal. The warm temperatures during the germination period may have weakened the seedlings compared with the cooler and drier conditions during germination in Year 2.

Hoveland et al. (1991), and Cuomo et al. (1999) also described the dependence of annual ryegrass and small grain pasture on autumn moisture and temperatures. Their research, conducted in the southern, humid USA, showed that seasonal forage yield could vary by as much as 500%, depending on autumn rainfall patterns and temperatures. Compared with locations further south, rainfall near the time of planting and subsequent autumn weather may have a greater influence on annual ryegrass accumulation in the lower Midwest because there are fewer days of ideal growing conditions.

Forage Quality
Forage quality (ADF, NDF, and CP) varied significantly by entry, location, year, and harvest date. Interactions between entries and locations and the three and four-way interactions with locations were not significant. Thus, data were pooled across locations within years. However, because of significant interactions between entries, years, and harvest dates, these results are discussed separately.

Stockpiled Barmultra and Marshall had equal ADF (avg. 206 g kg^-1) and NDF (avg. 330 g kg^-1) concentrations in December of Year 1 (Fig. 2, 3). Both the ADF and NDF concentrations of Barmultra and Marshall increased as the forage weathered during winter, with seasonal highs occurring in January or February. Most notable is the nearly 100 g kg^-1 increase in NDF between December and January of Year 1, which was likely a result of the freeze damage noted earlier. Cereal rye did not exhibit this type of freeze damage, and perhaps this is the reason it had ADF and NDF concentrations that were 23 to 104 g kg^-1 lower than the annual ryegrass cultivars. In addition, the ADF and NDF concentrations for cereal rye did not fluctuate as much as they did for the annual ryegrass. However, the maximum ADF and NDF concentrations for annual ryegrass were 252 g kg^-1 and 455 g kg^-1, respectively, which suggests that it was still of acceptable quality for most classes of beef and dairy cattle (National Research Council, 1996, 2001).

View larger version (16K): [in this window] [in a new window]   Fig. 2. Acid detergent fiber (ADF) of ‘Barmultra’ and ‘Marshall’ annual ryegrass and cereal rye, harvested monthly during the winters of 1998-1999 (Year 1) and 1999-2000 (Year 2). Data are pooled across two locations (Columbia and Mt. Vernon, MO) within years. Bars indicate standard errors; however, some error bars are smaller than the symbol and may not be visible.

View larger version (18K): [in this window] [in a new window]   Fig. 3. Neutral detergent fiber (NDF) of ‘Barmultra’ and ‘Marshall’ annual ryegrass and cereal rye, harvested monthly during the winters of 1998-1999 (Year 1) and 1999-2000 (Year 2). Data are pooled across two locations (Columbia and Mt. Vernon, MO) within years. Bars indicate standard errors; however, some error bars are smaller than the symbol and may not be visible.

View larger version (16K): [in this window] [in a new window]   Fig. 4. Crude protein (CP) of ‘Barmultra’ and ‘Marshall’ annual ryegrass and cereal rye, harvested monthly during the winters of 1998-1999 (Year 1) and 1999-2000 (Year 2). Data are pooled across two locations (Columbia and Mt. Vernon, MO) within years. Bars indicate standard errors; however, some error bars are smaller than the symbol and may not be visible.

In Year 2, Barmultra had a CP concentration of 216 g kg^-1 in December, which was 11 g kg^-1 more than Marshall and this ranking of treatments remained constant for the rest of the year (Fig. 4). Crude protein concentration for Barmultra and Marshall remained relatively constant from December through March. Cereal rye and Barmultra had a similar CP concentration in December, but the CP concentration of cereal rye declined by 35 g kg^-1 from December to March.

Our detergent fiber and CP values are similar to those reported by Mooso et al. (1990), Zhang et al. (1995), Eichhorn et al. (1996) in Louisiana and Lippke (1995) in Texas in winter. Although unexpected, our data suggest that the forage quality of stockpiled annual ryegrass in the lower Midwest is similar to that typically reported for the southern USA. In our study, there were often increases in ADF and NDF and decreases in CP concentrations during winter, but the loss in forage quality was, from a practical standpoint, small. In fact, the ADF and NDF concentrations reported for annual ryegrass in this study show that it usually has greater energy content than the early bloom alfalfa hay often fed to dairy cows or growing beef calves (National Research Council, 2001). Therefore, livestock operations could use stockpiled annual ryegrass to replace the hay or silage that is typically part of the rations fed to lactating dairy cows or growing beef calves.

	CONCLUSIONS

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Stockpiled annual ryegrass provided 825 to 2356 kg ha^-1 of forage for winter grazing, supporting our hypothesis that livestock operations in the lower Midwest could use it as a source of forage for deferred grazing in winter. Marshall consistently yielded more than Barmultra, while cereal rye generally yielded less than the annual ryegrass entries in Year 1 and more than the annual ryegrass entries in Year 2. Yields of stockpiled annual ryegrass were variable and were largely defined by autumn rainfall and winter temperatures. This makes the use of annual ryegrass riskier than the use of stored feeds like hay or silage. Perhaps a mixture of annual ryegrass and cereal rye would provide more uniform year-to-year forage production, as annual ryegrass produced more forage in Year 1 while cereal rye produced more forage in Year 2.

Stockpiled annual ryegrass provided good quality forage during winter both years. Forage quality of stockpiled annual ryegrass typically declined from December through February, with a larger decline in a normal winter (Year 1) than in a mild one (Year 2). Although forage quality tended to decline during winter, ADF did not exceed 252 g kg^-1 and NDF did not exceed 455 g kg^-1, which shows that stockpiled annual ryegrass could be a source of high-quality forage for all classes of beef and dairy cattle in winter. If annual ryegrass is to be stockpiled in the lower Midwest, Marshall would be preferred over Barmultra, as Marshall's forage yields were often greater than Barmultra's, while neither cultivar showed a consistent advantage in forage quality.

From a producer's perspective, the next step is to learn how to incorporate annual ryegrass into whole-farm systems in the Midwestern USA. For instance, annual ryegrass might be planted following corn (Zea mays L.) or forage sorghum [Sorghum bicolor (L.) Moench] harvested for silage or overseeded into standing corn or soybean [Glycine max (L.) Merr.] for grazing after grain harvest. Another possibility would be to plant annual ryegrass into perennial warm-season grass sods as is typically practiced in the humid, southern USA (Mooso et al., 1990; Cuomo et al., 1999). Although not researched in this region, such integrated systems might offer greater land use efficiency and lower overall production costs compared with current forage systems.

	NOTES

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Contribution from the Missouri Agric. Exp. Stn., Journal Series no. 13102.

¹ Mention of trade name or proprietary product does not constitute endorsement by the University of Missouri over the products of other manufacturers that may also be suitable.

Received for publication May 30, 2002.

	REFERENCES

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 

• Arnold, B.L., C.E. Watson, Jr., and N.C. Edwards, Jr. 1981. Registration of Marshall annual ryegrass. Crop Sci. 21:474–475.[Free Full Text]
• Balasko, J.A., G.W. Evers, and R.W. Duell. 1995. Bluegrasses, ryegrasses and bentgrasses. p. 357–371. In R.F Barnes et al. (ed.) Forages. Vol. I. The science of grassland agriculture. 5th ed. Iowa State Univ. Press, Ames, IA.
• Bishop-Hurley, G.J., and R.L. Kallenbach. 2001. The economics of grazing beef cows during winter. p. 274. In T. Terril (ed.) Proc. Am. Forage Grassland Council, Springdale, AR. 22–25 Apr. 2001. AFGC, Georgetown, TX.
• Cherney, D.J.R., and D.L. Robinson. 1985. Influence of climatic factors and forage age on the chemical components of ryegrass related to grass tetany. Agron. J. 77:827–830.[Abstract/Free Full Text]
• Creamer, N.G., M.A. Bennett, and B.R. Stinner. 1997. Evaluation of cover crop mixtures for use in vegetable production systems. HortScience 32:866–870.[Abstract/Free Full Text]
• Cuomo, G.J., D.D. Redfearn, J.F. Beatty, R.A. Anders, F.B. Martin, and D.C. Blouin. 1999. Management of warm-season annual grass residue on annual ryegrass establishment and production. Agron. J. 91:666–671.[Abstract/Free Full Text]
• Davis, E.E., J. McGrann, and J. Mintert. 1998. Retained ownership strategies for cattlemen [Online]. [4 p.] Available at http://trmep.tamu.edu/cg/factsheets/rm1-3.pdf [posted Aug. 1998; verified 6 Feb. 2003]. Agricultural Communications, Texas A&M Univ., College Station, TX.
• Eichhorn, M.M., Jr., G.J. Cuomo, and B.C. Venuto. 1996. Performance of annual ryegrass and cereal rye varieties on North Louisiana coastal plain soil. Circ. 134. Louisiana Agric. Exp. Stn., Baton Rouge, LA.
• Elbehri, A., and S.A. Ford. 1995. Economic analysis of major dairy forage systems in Pennsylvania: The role of intensive grazing. J. Prod. Agric. 8:501–507.
• Evers, G.W. 1995. Introduction to annual ryegrass. p. 1–6. In G.W. Evers and L.R. Nelson (ed.) Symposium on annual ryegrass, Tyler, TX. 31 Aug.–1 Sept. 1995. MP-1770. Texas Agric. Exp. Stn., College Station, TX.
• Fales, S.L., S.A. McMurry, and W.T. Mc Sweeny. 1993. The role of pasture in Northeastern dairy farming: Historical perspectives, trends, and research imperatives for the future. p. 111–132. In J.T. Sims (ed.) Agricultural research in the northeastern United States: Critical review and future perspectives. ASA, Madison, WI.
• Hanson, G.D., L.C. Cunningham, S.A. Ford, L.D. Muller, and R.L. Parsons. 1998. Increasing intensity of pasture use with dairy cattle: An economic analysis. J. Prod. Agric. 11:175–179.
• Hides, D.H. 1979. Winter hardiness in Lolium multiflorum: 3. Selection for improved cold tolerance and its effect on agronomic performance. Grass Forage Sci. 34:119–124.
• Hill, M.J., and C.J. Pearson. 1985. Primary growth and regrowth responses of temperate grasses to different temperatures and cutting frequencies. Aust. J. Agric. Res. 36:25–34.
• Hoveland, C.S., D.R. Hardin, P.C. Worley, and E.E. Worley. 1991. Steer performance on perennial vs. winter annual pastures in North Georgia. J. Prod. Agric. 4:24–28.
• Kallenbach, R.L., G.J. Bishop-Hurley, and M.D. Massie. 2001. Annual ryegrass for deferred grazing in Missouri. p. 304–309. In T. Terril (ed.) Proc. Am. Forage Grasslands Council, Springdale, AR. 22–25 Apr. 2001. AFGC, Georgetown, TX.
• Keatinge, J.D.H., M.K. Garrett, and R.H. Stewart. 1980. Response of perennial and Italian ryegrass cultivars to temperature and soil water potential. J. Agric. Sci. 94:171–176.
• Lawrence, J.D. 2000. Alternative retained ownership strategies for cow herds. [Online]. [7 p.] Available at http://www.econ.iastate.edu/faculty/lawrence/Acrobat/RETOWN2000withgraphs.pdf (posted Sept. 2000; verified 6 Feb. 2003). Iowa State Univ., Ames, IA.
• Lippke, H. 1995. Ryegrass nutritive value. p. 54–61. In G.W. Evers and L.R. Nelson (ed.) Symp. on annual ryegrass, Tyler, TX. 31 Aug.–1 Sept. 1995. MP-1770. Texas Agric. Exp. Stn., College Station, TX.
• Matches, A.G., and J.C. Burns. 1995. Systems of grazing management. p. 179–192. In R.F Barnes et al. (ed.) Forages. Vol. II. The science of grassland agriculture. 5th ed. Iowa State Univ. Press, Ames, IA.
• McCormick, M.E., J.D. Ward, D.D. Redfearn, D.D. French, D.C. Blouin, A.M. Chapa, and J.M. Fernandez. 2001. Supplemental dietary protein for grazing dairy cows: Effect on pasture intake and lactation performance. J. Dairy Sci. 84:896–907.[Abstract]
• Mooso, G.D., J.I. Feazel, and D.G. Morrison. 1990. Effect of sodseeding method on ryegrass-clover mixtures for grazing beef animals. J. Prod. Agric. 3:470–474.
• National Research Council. 1996. Nutrient requirements of beef cattle. 7th ed. National Academy Press, Washington, DC.
• National Research Council. 2001. Nutrient requirements of dairy cattle. 7th revised ed. National Academy Press, Washington, DC.
• Nelson, L.R. 1995. Ryegrass improvement and important cultivars. p. 7–13. In G.W. Evers and L.R. Nelson (ed.) Symp. on annual ryegrass, Tyler, TX. 31 Aug.–1 Sept. 1995. MP-1770. Texas Agric. Exp. Stn., College Station, TX.
• Nuttonson, M.Y. 1958. Rye-climate relationships and the use of phenology in ascertaining the thermal and photothermal requirements of rye. Am. Inst. Crop Ecol., Washington D.C.
• Pierce, V.L., J.L. Horner, J.C. Coomer, D.K. Hardin, J.A. Hoehne, A.M. Millmier, R. Randle, B.J. Steevens, and J.M. Zulovich. 2002. Competitive audit of the Missouri dairy industry [Online]. [67 p.] Available at http://agebb.missouri.edu/commag/dairy/audit/audit.pdf (posted Feb. 2002; verified 6 Feb. 2003). Univ. of Missouri, Columbia, MO.
• Parker, W.J., L.D. Muller, and D.R. Buckmaster. 1992. Management and economic implications of intensive grazing on dairy farms in the northeastern states. J. Dairy Sci. 75:2587–2597.[Abstract]
• Rao, S.C., and F.P. Horn. 1995. Cereals and brassicas for forage. p. 451–462. In R.F. Barnes et al. (ed.) Forages. Vol. I. The science of grassland agriculture. 5th ed. Iowa State Univ. Press, Ames, IA.
• Riewe, M.E., J.C. Smith, J.H. Jones, and E.C. Holt. 1963. Grazing production curves. I. Comparison of steer gains on Gulf ryegrass and tall fescue. Agron. J. 55:367–372.[Abstract/Free Full Text]
• Shenk, J.S., and M.O. Westerhaus. 1991. Population structuring of near infrared spectra and modified partial least squares regression. Crop Sci. 31:1548–1555.[Abstract/Free Full Text]
• Sladden, S.E., and D.I. Bransby. 1992. Stocking rate-gain relationships for sheep and cattle on ryegrass. p. 51–54. Proc. Am. Forage Grassland Council, Grand Rapids, MI. 5–9 Apr. 1992. AFGC, Georgetown, TX.
• Steel, R.G.D., and J.H. Torrie. 1980. Principles and procedures of statistics: A biometrical approach. 2nd ed. McGraw-Hill, New York.
• Van Soest, P.J., and J.B. Robertson. 1980. Systems analyses for evaluation of fibrous feeds. p. 49–60. In W.J. Pigden et al. (ed.) Standardization of analytical methodology for feeds. IDRC-134e. Int. Dev. Res. Centre, Ottawa, ON.
• Wall, L.L., and G.W. Gerke. 1975. An automated total protein nitrogen method. J. Assoc. Off. Anal. Chem. 58:1221–1226.
• Zhang, Y., L.D. Bunting, L.C. Kappel, and J.L. Hafley. 1995. Influence of nitrogen fertilization and defoliation frequency on nitrogen constituents and feeding value of annual ryegrass. J. Anim. Sci. 73:2474–2482.[Abstract]

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