Location: Dairy Forage Research2008 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
New field experiments and breeding nurseries of meadow fescue, smooth bromegrass, orchardgrass, and reed canarygrass were established in 2008 for sub-objectives 1C, 3A, and 3B. New field experiments of meadow fescue, orchardgrass, smooth bromegrass, and reed canarygrass were seeded, the first phase of a greenhouse experiment was conducted, and pasture and animal samples were collected in 2008 for sub-objective 1B and 3C. Field studies were established and evaluated for red clover and kura clover for sub-objectives (1A and 4C.1). Alfalfa samples were prepared for analysis and seed was produced for sub-objectives (2A.2 & 3C.2). These activities relate to the development of new germplasm to support NP215 Action Plan, Component 2, Pasture Management Systems. Work assessing polyphenol and forage management impacts on forage protein degradability continued in 2008 for subobjective 2A1 and a new field experiment examining alfalfa interseeding into corn was inititated in 2008 for subobjective 4C2. Multiple cuttings of alfalfa leaves and stems were ensiled during summer 2008 with the following treatments: untreated, lactic acid bacteria, cell-wall degrading enzymes and formic acid (Sub-objective 2 B). Experiments were completed during 2008 that assessed the effects of spontaneous heating on the nutritive value and energy density of stored alfalfa/orchardgrass hays for sub-objective 2C. These activities relate to the development of new germplasm and management practices to support NP215 Action Plan, Component 3, Sustainable Harvested Forage Systems.
1. Excessive heating reduces nonfiber carbohydrates and reduces energy density of hay. The costs of supplemental concentrates for dairy cows or other growing livestock have risen rapidly; therefore, preservation of forage (nonfiber) carbohydrates is increasingly important. Studies assessing the effects of spontaneous heating on the nutritive value and energy density of alfalfa/orchardgrass hays have shown that most reductions in energy density that occur in response to spontaneous heating are related directly to respiration of nonstructural carbohydrates. Smaller reductions in energy density are associated with decreased availability of forage proteins, but the effects of heating on the availability of forage fiber is relatively small. This suggests that minimization of respiratory processes within the hay bale, either by proper attention to moisture content or by the use of additives, is critical to maximizing the energy density of the stored forage. These activities support NP215 Action Plan, Component 3, Sustainable Harvested Forage Systems for Livestock, Bioenergy, and Bioproducts, Problem Statement J.
2. Polphenols and harvesting methods influence protein degradability in forage legumes. Unfortunately, protein in alfalfa undergoes excessive breakdown prior to gastrointestinal digestion, severely impairing protein use by livestock. In the future, the expression of protein-binding polyphenols such as condensed tannins and o-quinones in alfalfa should provide a sustainable approach for improving protein use by livestock. In this study, we examined how harvesting methods influenced protein degradation in hays and silages of polyphenol-free alfalfa and polyphenol-containing birdsfoot trefoil and red clover. We found that shifting from conventional roll conditioning to maceration (shredding) at harvest had little affect on our laboratory estimates of intestinal available protein in alfalfa. In birdsfoot trefoil, the combined effects of condensed tannins and maceration yielded up to 145% more intestinal available protein than alfalfa. With conventional conditioning, the action of mainly o-quinones in red clover yielded up to 88% more intestinal available protein than alfalfa. Surprisingly, maceration at harvest reduced the amount of intestinal available protein in red clover. Thus, genetically modifying alfalfa to produce tannins or o-quinones should greatly improve the utilization of protein by livestock. Mechanical maceration would also improve protein utilization if alfalfa contained condensed tannins. These results support NP215 Component 3, Sustainable Harvested Forage Systems, Problem Statement H. Need for improved plant materials that enhance the environment while improving the economic viability of harvesting and using grasses and forage legumes.
3. Pasture canopy structure influences potential stocking capacity and animal performance. Dry matter yield is often considered the primary criteria that determines the value of a temperate grass for pasture. Where managed intensive rotational grazing is employed, however, animals frequently have high nutritional requirements and are not forced to consume all the dry matter produced by the grass. The dry matter yield contained in different horizontal layers of the pasture canopy, and its quality, thus have an influence on potential stocking capacity and nutrient intake. Research on meadow fescue, orchardgrass, quackgrass, and reed canarygrass has identified differences in canopy structure of these grasses. Meadow fescue possesses a canopy structure that supports fewer animals during portions of the growing season but has greater quality throughout the canopy. The results provide guidelines by which producers may select and utilize different temperate grasses in rotational grazing systems. These results support NP215 Component 2, Pasture Management Systems to Improve Economic Viability and Enhance the Environment, Problem Statement G: Need for economically viable pasture-livestock systems for the Northeast and North Central States that enhance the environment.
4. Determining heritability of frost-seeded red clover establishment success. In the colder parts of the United States, in late winter after disappearance of snow cover, red clover is often broadcast seeded into forage legume-depleted grass pastures to increase pasture forage quality. This method of establishment is referred to as frost-seeding. However, in an estimated 30-40% of frost-seeded pastures in Wisconsin, USA the legumes fail to establish. Breeding for increased frost-seedability has not been attempted by plant breeders. This study measured the genetic basis of frost-seedability. Inheritance of frost-seeded seedling establishment traits is very low, suggesting that developing new varieties for this trait will be difficult. This study will help red clover breeders to optimize breeding programs to achieve selection gains for frost-seeded establishment. These results support NP215 Component 2. Pasture Management Systems, Problem Statement D. Need for appropriate plant materials to improve the economic viability and enhance the environment in pasture-based livestock systems.
5. Yellow x purple flowered alfalfa hybrid seed production using leafcutter bees. Yellow flowered by purple flowered alfalfa hybrids have been shown to produce increased hay yields. The alfalfa leafcutter bee is an important pollinator species used to produce alfalfa seed. This study examined leafcutter bee preference for purple flowered alfalfa versus yellow flowered alfalfa. Higher amounts of yellow to purple flowered alfalfa plants in the seed production environment was shown to produce less hybrid seed than would be expected without pollinator preference. These results are important to seed producers trying to maximize production of purple by yellow flowered alfalfa hybrid seed using alfalfa leafcutter bees. These results support NP215 Component 2. Pasture Management Systems, Problem Statement D. Need for appropriate plant materials to improve the economic viability and enhance the environment in pasture-based livestock systems.
Norman, R.C., Coblentz, W.K., Hubbell, D.S., Ogden, R.K., Coffey, K.P., Caldwell, J.D., Rhein, R.T., West, C.P., Rosenkrans, C.F. 2007. Effects of Storage Conditions on the Forage Quality Characteristics and Ergovaline Content of Endophyte-Infected Tall Fescue Hays. Crop Science. 47:1635-1646.