Volume 44 Number 2 Summer 1997

Marshall Ryegrass Dramatically Superior Under Grazing
Marshall (left) and Gulf (right) on Feb. 10, 1997.

David I. Bransby, Malcomb Pegues, and Randall Rawls

In grazing experiments at two locations in Alabama, on average, Marshall annual ryegrass produced 52% more animal weight gain than Gulf under grazing. This result is in stark contrast to results from mowing experiments.

Marshall is a variety of ryegrass that was developed and released by Mississippi State University in 1981. It was developed for its excellent cold tolerance, which makes it particularly suited to regions with cold winters. In fact, it is rated by most specialists as the most cold-tolerant variety on the market. However, in warmer regions the plant is not as tolerant to crown rust as Gulf.

Gulf is the first improved variety of ryegrass developed in the United States. It was released by the Texas Agricultural Experiment Station in
1958 for improved yield and improved tolerance of crown rust. However, Gulf ryegrass is low in cold tolerance.

Given the recognized difference in adaptation between these two varieties, market trends indicate that Marshall is the preferred variety as one moves North, but Gulf is used more in the Gulf Coast region. Mowing tests in Alabama showed that forage yields for Marshall and Gulf were similar in the South, but Marshall had a large advantage in the North. However, mowing does not simulate grazing. This means that forage yield differences from mowing experiments do not necessarily reflect animal production differences among different forages when they are grazed.

An AAES study was conducted to compare Marshall and Gulf ryegrass under continuous grazing in both warm and cold environments, and to relate these results to data from past mowing experiments. Stocker steers were grazed on four Marshall and four Gulf ryegrass pastures at the Gulf Coast Station near Fairhope and the Upper Coastal Plain Station near Winfield in winter of 1996-97. Steers weighing about 500 pounds were turned on to the pastures in early December, and were stocked at two animals per acre at Fairhope and 1.67 animals per acre at Winfield. They were weighed every 28 days, and pasture height was measured on weigh days.

At the Fairhope location steer weight gain was 77% greater for Marshall than for Gulf (see Table 1). At Winfield, this advantage was 27%. However, the stocking rate at Winfield was above optimum, so this test served as a comparison of the two varieties under stress conditions. Cattle on Gulf ryegrass at Winfield started to lose weight in February. Therefore, supplemental hay was provided for 34 days. Steers grazing Marshall received no hay, but still gained 27% more than those on Gulf. On average, pasture height across both locations was 31% greater for Marshall than for Gulf (5.09 inches and 3.90 inches, respectively).

Of particular interest is the dramatic advantage of Marshall over Gulf in the Gulf Coast region where Gulf is considered to be well adapted. This advantage was evident in the very first 28-day period, and continued to (see Table 2). This shows that, in this season, the superiority of Marshall was evident throughout the entire season, and not only in the middle of winter. Clearly, Marshall was superior to Gulf in both cold tolerance and tolerance to grazing, and it may also have some other production advantages that have not yet been discovered.

Rust was evident on both varieties in spring. It was more severe on Marshall, but did not seem to affect animal production. However, Jackson ryegrass is a variety that was developed from Marshall, and it has similar cold tolerance but greater tolerance to crown rust. Therefore, if rust is of concern, Jackson can be used as an alternative variety to Marshall. This variety will be included in future experiments for comparison with Marshall and Gulf.

An economic analysis of these preliminary results suggests that Marshall ryegrass was more profitable to graze than Gulf. If animals were contract grazed by a landowner for 35 cents per pound of weight gain, paid by a separate person who owned the cattle, profit from cattle grazing Marshall was nearly five times higher than for Gulf ($126.21 versus $21.71: see Table 3). This occurred despite a $3.90 lower seed cost per acre for Gulf (the analysis assumed a seeding rate of 30 pounds per acre and seed costs of 30 cents per pound for Gulf and 43 cents per pound for Marshall). Therefore, based on this study, an extra $3.90 per acre spent on seed for Marshall ryegrass gave $102.50, or nearly a 27-fold return on investment.

These results suggest that Marshall ryegrass was dramatically superior to Gulf throughout the season, even at the Gulf Coast; the profit advantage was substantially greater than the production advantage; and the advantage of Marshall over Gulf was much greater under grazing than under mowing. In addition, profit from stockers grazing Marshall ryegrass was comparable with many row crops.

Cattle on Marshall (left) at end of study in April 1997. Cattle on Gulf (right) at end of study in April 1997.

Bransby is a Professor of Agronomy and Soils, Pegues is an Assistant Superintendent of Gulf Coast Substation, and Rawls is Superintendent of Upper Coastal Plains Substation.

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