Lemus, R., Extension Forage Specialist, Mississippi State University Extension Service
Rivera, D., Assistant Extension/Research Professor, Mississippi State University
Johnson, B., Farm Manager, Mississippi State University

ABSTRACT

Grazing management influences of annual ryegrass and mixes with arrowleaf and berseem clovers were evaluated at Newton, MS during the 2009-10 growing season.  Clover systems showed a slight advantage over nitrogen fertilization, however, it should be noted that grazing period was shortened due to extreme weather conditions (cold temperatures and wet conditions) during the grazing trial, which may have affected the outcome of the study. Annual ryegrass combined with berseem clover had higher average daily gains compared to annual ryegrass alone or in combination with arrowleaf clover.

Introduction

Warm-season perennial grasses dominate most of the pastures in Mississippi, but climatic conditions allow for use of cool-season annual grasses and legumes overseeded or planted in a prepared seedbed in the fall for early winter and spring grazing. A goal of Mississippi cattle producers is to provide the nutrients their cattle require as economically as possible through grazing during the winter months. Due to rapidly increasing fertilizer prices, there has been a tremendous increase and interest in planting and grazing clovers with winter annuals (annual ryegrass and small grains).   Approximately 70% of these ryegrass pastures are established by over-seeding into warm-season perennial grasses (bermudagrass, bahiagrass, or mixed pastures) to extend the grazing season. 

Cool-season annual forages can extend the grazing period and reduce hay requirement because of their high nutritive value (Hoveland & Evers, 1995).  Annual ryegrass is a highly productive grass in the southern USA and it is adapted to most soils and tolerant to wet conditions and poorly drained soils. Ryegrass also tolerates close grazing, although if repeatedly grazed too closely, growing animal performance will be reduced.  On the other hand, cool-season legumes make most of their growth in the spring when temperature and rainfall are favorable.  Some clovers such as arrowleaf, ball, berseem and white are well complementary to the grazing system and can be grown in mixture with annual ryegrass (Coffey et al., 2002).  Clovers are an option to decrease the production cost associated with N fertilization because legumes have the ability to fix atmospheric N (Smith & Kallenbach, 2006).  Clovers differ in their tolerance and ability to persist in various soils. It is important to match the clover species or mixture of species to the different soils so that greatest returns can be realized as well as proper soil and water conservation.  Data has shown that incorporating clovers into annual cool-season will improve animal performance (Bishop-Hurley & Kallenbach, 2001).

The purpose of this demonstration was to compare the animal performance of annual ryegrass fertilized with nitrogen to ryegrass/clover mixtures for cool-season grazing with growing beef heifers.

Materials and Methods

The study was conducted at the Coastal Experiment Station in Newton, MS.  Six paddocks, each two acres, were utilized in the study.  The experimental design was a randomized complete design with three treatments replicated twice. The treatments include ‘Marshall’ annual ryegrass fertilized with ammonium nitrate (R), ryegrass + arrowleaf clover (RAC), and ryegrass + berseem clover (RBC).  The R treatment was fertilized with a total of 100 lb N/ac of ammonium nitrate (34-0-0) in a split application of 50 lb N/ac in the fall after establishment and 50 lb N/ac in the spring after the first grazing period. The other two treatments received 20 lb N/ac at time of establishment to allow ryegrass and clovers to become established.  Phosphorus and potassium levels in each paddock were adjusted based on soil test recommendations. Glyphosate was applied 3 weeks before planting for weed control and to reduce biomass present.  Treatments were established by broadcasting ‘Marshall’ annual ryegrass and arrowleaf and berseem clover at a rate of 30, 10 and 15 lb/ac, respectively. Clover systems showed a slight advantage over nitrogen fertilization, however, it should be noted that grazing period was shortened due to extreme weather conditions during the grazing trial, which may have affected the outcome of the study.  Ryegrass/clover mixtures received 25 lb N/ac after the first grazing period to stimulate growth. The initial stocking rate was approximately 486 lb of beef per ac (two 243 lb animals) with an estimated 50% fertilization rate. 

Grazing began on December 15, 2009 and first grazing ended on January 5, 2010.  The second grazing period started on April 8 and ended May 13, 2010.  Animal daily gain was measured within each 28-day period, allowing the pasture to rest for approximately 20 days.  Animals were exposed to a uniform hay ration during the rest period.  Between grazing periods, animals were removed from the experimental pastures and placed on spare pastures where the received mineral and hay supplementation because of inclement weather and poor forage growth.  Individual animal weights were recorded at the beginning and at the end of each grazing period to calculate animal daily gains (ADG) and gain per acre. Pre- and post-grazing forage samples were collected in each pasture to determine forage utilization in a temporal basis.  Forage were collected along three transects in the pasture and four samples were collected within each transect.  Two grazing cages were randomly also placed in each paddock to determine forage availability.

Biomass subsamples were collected pre- and post-grazing to determine grazing efficiency. Biomass samples were dried at 120 °F in a forced-air oven for 4–5 days 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), Total Sugars using the Foss 6500-C Near Infra-red Reflectance Spectroscopy (NIRS) instrument. 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 PROC GLM of SAS and means were separated by the Least Significant Differences (LSD) at α = 0.05.   

Results and Discussion

Beef steers grazing a mixture of ‘Marshall’ ryegrass with arrowleaf and crimson clover had higher animal daily gains, but means were not significantly different (Figure 1).  Both systems, RAC and RBC produced higher gain per acre when compared to ryegrass only (R).  Utilization rates were higher with ryegrass only early in the season, but greater with clover mixture late in the season (Figure 2).  The observed patterns could be related to more palatable ryegrass early in the season when clovers were not actively growing.  On the other hand, clovers are more active in the spring while ryegrass is becoming more mature.  Having clovers in the pasture might have contributed to more palatable forage.  The addition of arrowleaf clover into the mixture increased total forage production and clover percentage (P < 0.05) during January (Figure 3).

Figure 1.  Animal Daily Gain (ADG) on growing heifers when grazing different annual cool-season grass systems.

Figure 2.  Pasture utilization of grazing system during the assigned grazing periods.

Figure 3.  Percent clover distribution in pastures grazing during the 2009-10 season in Newton, MS.

 

Measurements of forage quality indicated a treatment x date interaction (Table 1).  There was a linear decrease in forage quality throughout the growing season (Redfearn, et al., 2002).  This was expected due changes in maturity of annual ryegrass later in the season.  Annual ryegrass had a higher crude protein in December while treatments containing clovers had a higher crude protein in April. Acid detergent fiber had a 100% decline in digestibility from December to May across all treatments while NDF and sugar concentration follow the same pattern.  Despite the decline in forage quality, animal gains were much higher during the second grazing period.  This is an indication that animals grazing high quality annual ryegrass in the season might be limited by fiber content.  While annual ryegrass forage quality might decrease later in the season, clovers will provide sufficient forage quality to sustain animal performance.

 

	First Grazing Period			Second Grazing Period
Treatments	15-Dec (Pre)	5-Jan (Post)		6-Apr (Pre)	13-May (Post)
	CP (%)
R	24.91	14.41		13.07	7.26
RAC	23.86	14.95		19.33	7.58
RBC	23.07	15.57		17.60	7.71
Mean	23.95	14.97		16.67	7.52
LSD0.05	NS	NS		1.85	NS
	ADF (%)
R	20.73	22.94		33.18	43.39
RAC	20.95	22.35		30.78	43.67
RBC	21.59	23.69		31.17	43.11
Mean	21.09	22.99		31.71	43.39
LSD0.05	NS	0.78		0.58	NS
	NDF (%)
R	40.54	36.98		55.04	68.91
RAC	38.92	35.87		47.00	68.30
RBC	38.74	37.94		50.51	67.61
Mean	39.40	36.93		50.85	68.27
LSD0.05	0.94	NS		2.34	NS
	Total Sugars (%)
R	8.33	16.20		11.50	4.68
RAC	9.06	16.96		9.33	4.12
RBC	10.04	15.40		9.94	5.13
Mean	9.14	16.19		10.25	4.64
LSD0.05	0.55	NS		1.20	NS

Table 1.  Forage quality of pasture systems pre and post-grazing utilization.

 

Conclusion

These results demonstrate that livestock operations in Mississippi could use annual ryegrass with clover mixture for winter grazing. It is important to keep in mind that cattle operations are not exactly alike. They vary in soil, climate, size, producer goals, and amount of time available to manage the operation. Each producer must develop a pasture system that best fits their situation and utilizing legume species adapted to his area. Important factors in developing a good forage system include knowing the soil, selecting an adapted species, and understanding livestock nutrients requirements and forage management.

Literature Cited

Bishop-Hurley, G. J., and Kallenbach, R. L. 2001. The economics of grazing beef cows during winter. Pages 274 in: Proc. American Forage and Grassland Council. 22-25 April, 2001. Springdale, AR. AFGC, Georgetown, TX.

Coffey, K. P., Coblentz, W. K., Montgomery, T. G., Shockey, J. D., Bryant, K. J., Francis, P. B., Rosenkrans, C. F., Jr., and Gunter, S. A. 2002. Growth performance of stocker calves backgrounded on sod-seeded winter annuals or hay and grain. J. Anim. Sci. 80:926-932.

Hoveland, C.S. and Evers G.W.1995. Arrowleaf, crimson, and other annual clover. p. 249-260.  In: R. F. Barnes, et al. (ed.) Forages: The science of grassland agriculture. 5th ed. Iowa State Univ.  Press, Ames, IA.

Redfearn, D. D., Venuto, B. C., Pitman, W. D., Alison, M. W., and Ward J. D. 2002. Cultivar and environmental effects on annual ryegrass forage yield, yield distribution, and nutritive value. Agron. J. 42:2049-2054.

Smith, L. B., and Kallenbach, R. L. 2006. Overseeding annual ryegrass and cereal rye into soybean as part of a multifunctional cropping system: II. Forage yield and nutritive value. Online. Forage and Grazinglands doi:10.1094/FG-2006-0907-02-RS.

Acknowledgment

Thank you to Wax Seed Company and Cal/West Seeds for providing seed to conduct this study.  Thank you to Chad Cruter for helping with data collection and processing.

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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