Lemus, R., Extension Forage Specialist, Mississippi State University Extension Service
Morrison, J.I, Research Associate, Mississippi State University
White, J.A., Forage Variety Testing Manager, Mississippi State University

ABSTRACT

Winter forage production is important to most types of livestock enterprises in the southern USA.   Small grains such as cereal rye could provide early fall grazing and increase the total number of grazing days.  There is very little information on the advantage of ploidy and maturity of annual ryegrass on additive mixtures.  The objective was to determine the forage production and quality from annual ryegrass as a monoculture versus additive mixtures (ploidy and maturity) including cereal rye. The study results indicated that there was very little advantage among annual ryegrass mixes in forage production and quality parameters.  The benefit of cereal rye for early forage production could have been impaired by the aggressiveness of the annual ryegass planted at too high of a seeding rate that recommended on mixtures.  There is a need to study these mixes at lower seeding rates for the ryegrass to give rye a competitive edge early in the growing season.

INTRODUCTION

Annual ryegrass (Lolium multiflorum Lam.) and cereal rye (Secale cereale L.) as monocultures or additive mixes can extend the grazing season in the southeastern USA.  The utilization of annual cool-season forages is very important for the stocker cattle industry in Mississippi where the impact of high quality forage on animal performance very relevant.  These operations seek to maximize profitability by minimizing input costs and optimizing forage production, while maintaining economic levels of beef production.  In addition, some cow-calf producers retain ownership of stocker calves through backgrounding to capture additional value (Lawrence, 2000).  A study conducted in Missouri indicated that beef production from high quality pastures cost 25 to 50 percent less than using stored forages (Bishop-Hurley & Kallenbach, 2001).

The establishment of annual winter pastures from seed can be expensive and producers need to prioritize on forage utilization to extend the grazing season and optimize forage production.  Some producers inquire about the agronomic advantages that annual ryegrass mixtures with different ploidy and maturity levels could have on botanical composition to maintain grazing persistence, extend the grazing period, and maintain yield stability and productivity.  Swift et al. (1993) reported that when grazing sheep under continuous stocking, swards of diploid annual ryegrass had 23% higher tiller densities than tetraploid swards.  Diploid tiller density was 43% greater than the 926 tillers ft^-2 observed with the tetraploid ryegrass/clover swards.  Other producers also develop complex mixtures of grass and legumes in order to improve forage quality while reducing the need of nitrogen fertilization.  Greater forage production may allow for greater stocking rates and perhaps greater animal production per unit area, which may offset some re-establishment costs (Sanderson, Corson, Rotz, & Soder, 2006).  A 3-year study conducted at University of Arkansas indicated that a mixture of cereal rye and annual ryegrass provided higher total animal gains (lbs/head) when compared to ryegrass alone or a wheat and annual ryegrass mixture in pastures that were stocked continuously from mid-December through mid-April (Jennings & Coffey, 2006).

From a producer's perspective, the next step is to learn how to incorporate annual ryegrass mixes with different ploidy levels and maturities to extend the grazing season.  Perhaps a mixture of annual ryegrass and cereal rye would provide more uniform seasonal forage production, as annual ryegrass produced more forage late in the winter while cereal rye produced more forage in late fall. There is little data in Mississippi on the productivity of diploid and tetraploid mixes and if they would provide an advantage on extending the grazing season. Our objective was to determine the forage production and quality from annual ryegrass with different ploidy and maturity levels as a monoculture versus additive mixtures including cereal rye.

MATERIALS AND METHODS

The study was conducted at the Forage Unit located in the Henry H. Leveck Animal Research Farm at Mississippi State University (33º 25’ 22” N, 88º 47’ 32” W).  The soil type was a Marietta soil (Fine-loamy, siliceous, active, thermic Typic Endoaquults).  The study was randomized complete block design replicated four times.  The study consisted of ten treatments containing early and late maturing diploid and tetraploid annual ryegrass as a monoculture, additive mixtures or combined with cereal rye.  Cereal rye was not planted as a monoculture because it matures very early in Mississippi and it could impact length of the grazing season (White et al., 2012; White, Lemus, Saunders, Fitzgerald, & Johnson, 2013).  Treatment description and recommended seeding rates are described in Table 1.  The study was planted on October 20, 2010 and fertilized according to soil test recommendations.  Potassium and lime were applied during land preparation at rates of 90 lb K and 2 tons lime/ac, respectively.  All the plots were fertilized with 100 lb/ac of 15-15-10 at planting.  Plots were fertilized with 50 lb N/ac on December 7 using ammonium nitrate (34-0-0).   Plot size was 6 ft by 11 ft.  Plots were harvested five times during the growing season (February 14, March 4, March 21, April 12 and May 9) when 50 percent of the plots reach 12 to 15 inches in height.  Leaf Area Index (LAI) was measured prior to each harvest using a LI-COR-2000 plant canopy analyzer (LI-COR Biosciences, Lincoln, NE).

Treatment	Variety	Ploidy Level1	Maturity	Seeding Rate (lb/ac)
BG	Bulldog Grazer	2n	Early	30
CH	Chipola	2n	Early	30
MA	Marshall	2n	Late	30
MA/BG	Marshall + Bulldog Grazer	--	--	15 + 15
MA/CH	Marshall + Chipola	--	--	15 + 15
MA/CR	Marshall + Elbon Cereal Rye	--	--	25 + 85
TT	TAM TBO	4n	Late	30
TT/BG	TAM-TBO + Bulldog Grazer	--	--	15 + 15
TT/CH	TAM-TBO + Chipola	--	--	15 + 15
TT/CR	TAM-TBO + Elbon Cereal Rye	--	--	25 + 85

Table 1.  Annual ryegrass varieties, ploidy level, maturity and seeding rates.  ¹2n = Diploid and 4n = Tetraploid.

Plots were harvested using a sensation mower equipped with a bagging system.  A 42-inch swath was removed from the center of the each plot to reduce border effect.  Biomass subsamples were collected at each harvest and dried at 120 °F in a forced-air oven for 4–5 days for dry matter determination and ground to pass a 2-mm screen using a Wiley Mill (Thomas Scientific, Swedesboro, NJ, USA).   Biomass samples were analyzed for Crude Protein (CP), Acid Detergent Fiber (ADF), Neutral Detergent Fiber (NDF), Acid Detergent Lignin (ADL), and sugar based parameters (fructan, total sugar, and water soluble compounds) using the Foss 6500-C Near Infra-red Reflectance Spectroscopy (NIRS) instrument Foss North America, Eden Prairie, MN). The samples were scanned using Foss ISI Scan software and prediction equations developed by the NIRS Forage and Feed Testing Consortium (Hillsboro, WI, USA).  Data was analyzed using the General Linear Models of SAS (PROC GLM) and means were separated by the Least Significant Difference (LSD) at α = 0.05 or α = 0.10 when applicable (SAS, 2013).

RESULTS AND DISCUSSION

Forage Production

A total yield effect was observed among treatments (P<0.10).  TAM-TBO (TT) and Marshall/Elbon Rye (MA/CR) treatments provided higher yields compared to the rest of the monocultures or mixtures while TT/CR had the lowest biomass production (Figure 1).   A yield by harvest effect was observed, but treatment or interactions were not detected.  Harvest yields were comparable between the February and mid-March harvests while yield differences were observed among the rest of the harvest dates (Figure 2). This study indicated that there was no advantage in forage production by combining ryegrass varieties based on maturity or ploidy level.  This could be due to the fact that fall and winter temperatures   were relatively mild while precipitation was extremely low (Figure 3).

Figure 1.  Total seasonal yield for annual-cool season ryegrass monocultures or additive mixes.

Figure 2.  Yield harvest distribution for annual-cool season ryegrass monocultures or additive mixes.  Data average over treatments and replications.

 

Figure 3.  Monthly average temperature and precipitation from October 201o to May 2011.

Leaf Area Index

Leaf Area Index (LAI) was not significant among treatments.  There was a harvest effect in LAI with the early March harvest having the highest value and May the lowest.  This trend was expected since annual ryegrass typically reaches peak growth in March and April and lower LAI in May represented typical plant senescence (Figure 4).

Figure 4. Harvest effect on leaf area index of annual ryegrass plated as a monoculture or additive mixtures.

Forage Nutritive Parameters

Forage quality parameters (CP, ADF, NDF, and ADL) were mainly affected by harvest date (Table 2) with the exception of ADF that was influence by a treatment by harvest interaction (data not shown).  This interaction indicated that ryegrass mixtures and mixtures containing cereal rye had lower NDF than the monoculture treatments but not necessary significant.  Crude protein was higher in February and declined 41% by May due to maturity and senescence.  Acid detergent fiber increased 39% from February to May, but values were very consistent through mid-season.  Neutral detergent fiber had the lowest concentration in February and was very consistent throughout the harvest regime, but increase of 27% by the end of the season.  Acid detergent lignin which can have a major impact in forage digestibility was fairly consistent across the harvest regime.  Sugar based compounds (fructan, total sugar, and water soluble compounds) accumulation was higher in February and May (data not shown).  This trend is related to slower growth during the cold period in February and accumulation of nutrients during the senescence period in May when temperatures are above 70 ºF.  The concentrations of sugar based compounds also varied, with treatments containing Marshall ryegrass having the highest sugar concentrations throughout the growing season. Phosphorus, K, Ca and Mg concentrations in the tissue were consistent across the growing season with mean values of 0.30, 2.44, 0.66, and 0.38%, respectively.

	Harvest Date
Parameter1	Feb-14	Mar-4	Mar-21	Apr-12	May-9	Mean	LSD0.05
	---------------------------------------------------- % ----------------------------------------------------
CP	24.00	20.65	22.11	22.29	14.14	20.66	1.03
ADF	22.00	34.51	32.34	31.29	32.95	30.62	1.17
NDF	40.32	54.55	49.74	49.14	51.16	48.98	1.79
ADL	6.09	7.00	7.00	7.26	7.70	7.01	0.43

Table 2.  Harvest effect on forage quality parameters.  ¹CP = Crude Protein; ADF = Acid Detergent Fiber; NDF = Neutral Detergent Fiber; ADL = Acid Detergent Lignin.

CONCLUSION

Although studies in the past have demonstrated an advantage of using small grains in combination with annual ryegrass in grazing systems that advantage was not observed in this study.  This could be attributed to above normal temperatures as well as below normal precipitation.  Another factor that could have affected the performance of cereal rye in the mixtures or perhaps the combination of ploidy and maturity treatments, is the dominance and competitiveness of the annual ryegrass under optimum temperatures.  Perhaps, annual ryegrass should have been planted at lower seeding rates.  Further studies to compare diploid and tetraploid annual ryegrass at different mixture proportions are needed to determine yield and forage quality benefits.

LITERATURE CITED

Bishop-Hurley, G.J., & 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.

Jennings, J., & K. Coffey.  (2006). Using cereal grain forages and mixtures with annual ryegrass for grazing.  Univ. of Arkansas Coop. Ext. Serv.  Pub. FSA3064. Online (http://www.uaex.edu/Other_Areas/publications/PDF/FSA-3064.pdf).  Verified September 11, 2013.

Lawrence, J.D. (2000). Alternative retained ownership strategies for cow herds.  Iowa State Univ., Ames, IA.  Online (http://www.econ.iastate.edu/faculty/lawrence/Acrobat/RETOWN2000withgraphs.pdf).  Verified September 11, 2013.

Sanderson, M.A., Corson, M.S., Rotz, C.A., & Soder, K.J. (2006). Economic analysis of forage mixture productivity in pastures grazed by dairy cattle. Online. Forage and Grazinglands doi:10.1094/FG-2006-0929-01-RS.

SAS Institute.  (2013). SAS user’s guide: statistics, version 9.3. SAS Inst., Cary, NC.

Swift, G., J.E. Vipond, T.H. McClelland, A.T. Cleland, J.A. Milne, & E.A. Hunter.  1993.  A comparison of diploid and tetraploid perennial ryegrass and tetraploid ryegrass/white clover swards under continuous sheep stocking at controlled sward heights. 1. Sward characteristics. Grass and Forage Science, 48: 279–289. doi: 10.1111/j.1365-2494.1993.tb01861.x

White, J.A., R. Lemus, J.R. Saunders, L. Fitzgerald, B. Johnson, & J. Morrison. (2012). Mississippi Annual Cool-season Forage Crop Variety Trials (2011-2012).  Mississippi Agricultural & Forestry Experiment Station (MAFES).  Bul. IB0470.

White, J.A., R. Lemus, J.R. Saunders, L. Fitzgerald, & B. Johnson. (2013). Mississippi Annual Cool-season Forage Crop Variety Trials (2012-2013).  Mississippi Agricultural & Forestry Experiment Station (MAFES).  Bul. IB0479.

ACKNOWLEDGEMENT

Thank you to the student workers Cory Davis, Parker Evans, Daniel Moore, Jonathan Norton and Isaac Pickett for their assistance in cultivating, packing, planting, harvesting, grinding and recording plot data.

DISCLAIMER

Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by Mississippi State University and does not imply its approval to the exclusion of other products or vendors that also may be suitable.

 

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