The best grass for cattle depends entirely on the specific climate, soil conditions, and production goals of the operation. The optimal choice is not a single superior species, but the most geographically and seasonally appropriate forage that meets the nutritional demands of the livestock. Selecting the right forage is important, as quality directly impacts animal health, weight gain, and reproductive success.
Determining Forage Quality
Forage quality is objectively measured using scientific benchmarks that quantify the nutritional value of the grass. Crude Protein (CP) is a primary metric, estimating the total nitrogen content available for muscle growth, milk production, and maintenance. Total Digestible Nutrients (TDN) estimates the energy content, calculated from fiber components like Acid Detergent Fiber (ADF). Higher TDN values indicate greater energy density, which is important for high-producing animals such as lactating cows.
Neutral Detergent Fiber (NDF) measures the total fiber content, which influences how much an animal can physically consume. High NDF values limit intake because the rumen fills quickly, while lower NDF allows for greater consumption. Although palatability affects intake, ADF and NDF metrics predict how well the forage will support animal performance. As grass matures, the fiber content increases, and both CP and TDN values decline, reducing the overall feeding quality.
Characteristics of Cool-Season Grasses
Cool-season grasses are C3 plants that thrive in regions with cold winters and moderate summers, peaking in growth during the spring and fall. Tall Fescue is widely used across the central and eastern United States due to its persistence and tolerance of poor soils, drought, and heavy grazing. However, the common Kentucky-31 variety produces ergot-alkaloids, which cause fescue toxicosis in cattle. This toxicity leads to poor circulation, reduced weight gain, and heat stress, requiring producers to use novel endophyte varieties or dilute the forage with legumes.
Orchardgrass and Ryegrass offer higher palatability and better forage quality than Tall Fescue. Orchardgrass is a high-quality bunch grass known for rapid regrowth, making it suitable for frequent rotational grazing. Perennial Ryegrass is noted for its high Crude Protein and digestibility, but it is less persistent and has lower winter hardiness than Orchardgrass or Tall Fescue. Both species decline rapidly in quality as they mature, necessitating careful management to maintain them in a leafy state for optimal nutrition.
Characteristics of Warm-Season Grasses
Warm-season grasses are C4 plants adapted to hot, humid climates and are the primary forage in the Southern United States. Species like Bermudagrass and Bahiagrass are highly productive during the summer when cool-season varieties are dormant. Bermudagrass is a productive, sod-forming grass that yields well when fertilized and offers good drought tolerance. Bahiagrass is a hardy alternative that tolerates sandy soils and lower fertility conditions more effectively than Bermudagrass.
While these grasses provide abundant summer growth, their nutritional value, particularly Crude Protein and digestibility, tends to be lower than cool-season varieties. Sorghum-Sudangrass hybrids are fast-growing summer annuals used to fill the mid-summer forage gap, but they carry unique management risks. They can accumulate toxic levels of nitrates after heavy nitrogen application or drought stress, and produce prussic acid (cyanide) when damaged by frost or wilting. To mitigate these risks, grazing is avoided until the plants are at least 18 to 24 inches tall, and caution is exercised after a frost.
Maximizing Forage Health Through Grazing Management
Effective grazing management promotes plant health and maximizes nutrient availability, allowing the inherent quality of the grass to be realized. Continuous grazing, where cattle access a single pasture for an extended period, often leads to overgrazing of preferred species. This selective pressure stresses desirable forages, eventually reducing the overall quality and productivity of the pasture.
Rotational grazing involves moving livestock frequently between smaller paddocks, allowing forages sufficient rest and recovery time. This rest period, often 21 to 30 days, is necessary for the grass to replenish root reserves and regrow a healthy leaf area. Implementing a rotational system improves forage utilization, increases pasture productivity, and promotes better soil health by reducing compaction and distributing manure. Maintaining proper soil fertility, including monitoring pH and following a targeted fertilization program, is also necessary to sustain high yields and nutritional goals.