Linda Benedict, Scaglia, Guillermo
Bermudagrass is an important warm-season, perennial, sod-forming forage grass grown across the southeastern United States. Bermudagrass is productive from spring until fall and is well-suited for grazing or hay production. It is a high-yielding grass; 5 to 7 tons of hay per acre can be produced with good management and ample moisture. In the South, beef cattle and dairy farms depend on bermudagrass as primary grazed forage from early spring until autumn. Thousands of tons of bermudagrass hay are fed to beef and dairy herds during winter, transition periods of seasonal deficiencies in forage available, and drought periods. Bermudagrass stands often persist and remain productive for more than 35 years, if properly managed. Most are tolerant to acidic and sandy soils, moderate to heavy grazing pressure, variable rainfall distribution, and differing management. Almost all are dual-purpose, producing pasture forages and hay.
To accomplish the objective of producing beef and hay from the same area, pastures have to be stocked with fewer animals per acre, allowing excess forage not consumed by cattle to be harvested as hay. This approach is detrimental to the total beef that can be produced on bermudagrass pastures but will offer the possibility to generate income from hay. The purpose of this trial was to evaluate Tifton 85, Alicia and Jiggs bermudagrass hybrids as dual-purpose forages. The hybrid Coastal was the first hybrid bermudagrass developed for forage production and sometimes will be used in this article as the standard to which the other bermudagrass hybrids are compared.
Characteristic of the bermudagrass hybrids used in the study, Tifton 85 is an F1 hybrid between a plant introduction from South Africa (PI 290884) and Tifton 68. It is taller and has larger stems, broader leaves and darker green color than most commercially available bermudagrasses. It has large rhizomes and very large stolons that spread rapidly and quickly cover the ground. It is, however, harder to establish a stand of Tifton 85 than Coastal or Jiggs.
Tifton 85 establishes rapidly from sprigs or tops. The larger and thicker stems of Tifton 85 increase the time required for drying to make hay by approximately 12 hours. Consumer perception is that thicker stems are related to low nutritive value. This perception, although false, sometimes limits the market for Tifton 85 hay. The increased digestibility of Tifton 85 over other hybrids is most likely due to different chemical bond ratios in the plant’s fiber fraction. Tifton 85 is highly resistant to leaf rust.
Alicia, a variety imported from South Africa, establishes aggressively from either tops or sprigs. It spreads primarily by stolons and has fewer rhizomes, but it spreads and becomes established more rapidly than other hybrids. Under moderate to heavy grazing and fairly severe winters, its recovery in the spring has been slow. Alicia is popular horse hay because of its fine stems. Digestibility of Alicia usually is less than most bermudagrasses. Alicia is extremely susceptible to leaf rust.
Jiggs establishes easiest of all varieties and quicker than Coastal on heavy-textured soils. It is adapted to various soil types and even does well on heavy, wet soils. Jiggs is easy to plant by tops. The thin stems of Jiggs also make it a desirable variety for hay production. Recent research, however, has shown that Jiggs has lower production and nutritive value than other improved bermudagrass hybrids. It does not have many rhizomes and does not produce as much as Tifton 85 in a drought.
Bermudagrass response and animal performance
In three consecutive years, 36 spring-weaned steers (initial body weight = 555 pounds) per year were rotationally stocked (3.3-acre pastures) for an average of 140 grazing days between June and October on three different bermudagrass hybrids (Alicia, Tifton 85 and Jiggs) at a stocking density of eight to 10 steers per acre (variable through the grazing season). Fertilization rate was 217 pounds per acre of urea initially and each time round bales of hay (900 pounds average weight) were harvested. Bermudagrass forage mass available (pounds per acre) was estimated and sampled for nutritive value analysis. Samples were taken at the beginning of the study and every 28 days thereafter during the grazing period. Individual animal weights were taken every 28 days coinciding with the bermudagrass sampling.
The three hybrids did not differ in the availability of forage mass throughout the grazing season. See Figure 1. Crude protein, acid detergent fiber and neutral detergent fiber concentrations also did not differ. These variables are important because they are closely related to the digestibility of the forage and the potential forage intake of the animal. The lack of differences may imply that animals should perform similarly. Average daily gains, however, of steers grazing Alicia were smaller than those grazing on Tifton 85 or Jiggs. See Figure 2. A closer look at the nutritive value of the different hybrids reveals that Alicia has a greater concentration of lignin, a plant structural carbohydrate that is not digested by the microbes in the rumen. See Figure 3. It is known that lignin concentration and some chemical linkages in its structure in many grasses and legumes may impair digestibility of the forages, probably decreasing the amount of forage that the animals consumed.
A common variable used to express nutritive value of forages is Total Digestible Nutrients (TDN). As indicated in Figure 4, TDN levels for the different hybrids were similar. In terms of hay produced, Jiggs produced an average of seven bales per acre, which was similar to Tifton 85 (7.5 bales) but more than Alicia (5.5 bales per acre).
Hay prices skyrocketed in 2011 because of drought conditions in many beef cattle states. According to the 2011 LSU AgCenter Agricultural Summary, many Louisiana hay producers were able to sell their hay in drought-stricken areas such as Texas for a good price. Under the conditions of the present experiment, managing bermudagrass for grazing and hay production, assuming a cost of $320 per acre (2012 Beef Cattle and Associated Forage Crop Production in Louisiana), is a profitable management strategy for producers in south Louisiana. The drought situation certainly would increase the profitability of these management practices, but even with average historic prices ($48 per round bale), management of bermudagrass for grazing and hay production is a viable alternative for beef cattle producers.
Guillermo Scaglia, Associate Professor, Iberia Research Station, Jeanerette, La.
Read about Forage Nutritive Value Characteristics, including crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), lignin and total digestible nutrients (TDN).
(This article was published in the summer 2012 issue of Louisiana Agriculture magazine.)