Location: Dairy Forage Research2011 Annual Report
1a. Objectives (from AD-416)
Objective 1: Overcome the production and profitability problems suffered in grazing-based systems because of poor plant persistence, inconsistent forage quality, and lack of resilience/stability. Objective 2: Develop new alfalfa (Medicago sativa L.) production systems that are less costly, more productive, and of greater value for livestock and biomass conversion. Objective 3: Develop improved understanding of the fundamental physiological, anatomical, and genetic controls that affect forage quality during plant development and digestion in the rumen. Objective 4: Broaden the range of alternative forage cropping systems to fulfill dietary needs, reduce environmental risk, and improve management flexibility.
1b. Approach (from AD-416)
We propose to develop new and more efficient management strategies and new forage cultivars, focused on four basic research themes related to forage plants and systems: (1) grass-based management-intensive rotational grazing systems, (2) harvested alfalfa as a bioenergy feedstock or livestock feed, (3) selection criteria for improving forage quality of pastures and harvested forages, and (4) alternative establishment methods and forage cropping systems. Hypothesis-driven research will be conducted largely with field trials designed to test new or improved cropping systems, management strategies, establishment methods, or germplasms in direct comparison to current or existing treatments. Field studies will be supplemented with laboratory analyses of forage characteristics related to nutritional value, plant cell walls, physical traits of stems and leaves, or DNA markers to identify functional relationships of field observations with expected ruminal livestock performance, further supplemented with animal evaluations in some cases. New forage cultivars and management strategies will be used to streamline forage production systems, increasing profitability and sustainability, while lessening environmental impact. We will publish numerous scientific articles that will add significant new findings to the scientific literature and will disseminate our findings to stakeholders in the agricultural community via a wide range of outreach programs and methods.
3. Progress Report
Harvesting and data analysis were completed on existing field experiments of meadow fescue, orchardgrass, smooth bromegrass, timothy, and reed canarygrass. New field experiments were established for meadow fescue, orchardgrass, meadow bromegrass, timothy, and reed canarygrass. We completed data collection from field and greenhouse studies of pasture grass response to grazing management variables, and analysis of samples from pasture utilization studies to support NP 215 Action Plan, Component 2, Objective G. Progress was made toward enhancing our knowledge of sub-optimal harvest and storage of dairy-quality forages in support of NP215 Action plan, Component 3, Objective J2. Extensive summaries of data for outdoor storage of hay in northern environments, as well as the consequences of spontaneous heating in large hay bales, were completed. Optimal establishment times and harvest managements were identified for fall-grown oat cultivars in support of NP215 Action plan, Component 3, Objective J2. Supporting Component 3, Objective J, work to evaluate plant growth regulators for aiding the establishment of interseeded alfalfa without limiting corn silage yields was expanded to include parallel studies with red clover. Other studies aimed to further refine seed spacing requirements for maximizing biomass alfalfa yield continued and additional sites in WI and MN will be seeded in 2011.
1. Characteristics of temperate pasture grasses that regulate intake by grazing cattle. The yield, height, nutritive value, and distribution and proportion of the leaf and stem fraction (the sward structure) of temperate grasses used in pastures differ during the growing season, which may influence intake by grazing livestock. Because pasture is the primary source of feed, differences in intake will impact milk productivity of dairy cows. ARS researchers at Madison, Wisconsin conducted a study to determine which characteristics have the most influence on intake by grazing cattle in order to identify grasses with superior canopy traits and better understand how productivity of grazing cattle can be improved. The researchers found that the density of the leaf fraction, followed by the stem density, has the greatest effect on intake by grazing cattle. These traits were more important than total yield, height, and nutritive value of the pasture. Results of the study provide producers with pasture management guidelines for improving profitability by maximizing intake of high quality leaf tissue, reducing use of supplement, and knowing when animals should be rotated to new pastures.
2. Assessment of unique quality characteristics of fall-grown cereal grains. Recent research has shown that cereal-grain forages that joint and exhibit stem elongation following late summer seeding (oat or triticale) will out-yield forages that remain vegetative (wheat) by an approximate 2:1 ratio by late fall. In addition, these forages display some unique nutritional characteristics, including low concentrations of fiber and lignin, as well as higher concentrations of plant sugars. In a previous study, ARS resesarchers at Madison, Wisconsin demonstrated that these forages also display relatively stable estimates of energy across a wide fall-harvest window that coincided with stem elongation for both oat and triticale tillers, and emergence of seedheads for oat tillers. In this study, researchers assessed the digestibility of fiber from these fall-grown cereal-grain forages. Based on the researchers' results, elongating cultivars will retain relatively stable concentrations of fiber and dry matter digestibility throughout stem elongation, but these nutritional characteristics may decline with further tiller development. However, the natural accumulation of sugars as a mechanism against freeze damage (winter hardening) may offer some potential to offset associated depressions in fiber digestibility, thereby partially maintaining estimates of available energy from these forages. Based on a large body of previous research, the nutritive value and fiber digestibility for spring-planted oat are both well defined; the current work suggests that fall-grown oat is nutritionally superior, and that livestock producers can use the unique nutritional traits of these forages to their considerable advantage under specific production scenarios.
3. Yield, soil nitrate, and spring runoff characteristics of no-till silage corn grown with companion crops and manure. Corn silage is the predominant forage fed to cattle in the Midwestern United States, but its production can contribute to groundwater contamination, eutrophication of natural ecosystems, and hypoxia in coastal waters by soil, phosphorus, and nitrates. The production of silage corn with companion crops (e.g. cover crops or living mulches) is therefore widely recommended for reducing soil and nutrient losses from cropland and for maintaining or improving crop yields, nutrient cycling, and soil quality. Few studies have, however, compared the productivity and efficacy of perennial legume versus annual grass companion crops for silage corn fertilized with manure. Therefore, in this study, ARS researchers at Madison, Wisconsin evaluated the production of feed and the potential loss of nutrients and soil from fall versus spring manured corn grown in rotation with kura clover living mulch or interseeded red clover, or grown continuously with interseeded ryegrass, fall-seeded rye, or no companion crop. Overall, no system was clearly superior in all agronomic and environmental traits, thus companion crop selection and manure management for silage corn will depend on protein and feed energy requirements for cattle and the susceptibility of cropland to soil and nutrient runoff. In ongoing work, ARS reserchers are working to improve the practicality, reliability, and yield of silage corn grown in rotation with interseeded forage legumes. Such systems should improve the profitability of corn-legume rotations for farmers, while helping to protect cropland, natural ecosystems, and water resources.
Riday, H. 2010. Red Clover Breeding Progress. Plant Breeding. 4:22-29.