2012 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.
Progress was made toward the development of a new germplasm. 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. Data collection from field and greenhouse studies of pasture grass response to grazing management variables, and analysis of samples from pasture utilization studies were completed. Progress was made toward enhancing the knowledge of sub-optimal harvest and storage of dairy-quality forages. 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. 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 are continuing. Breeding progress has been made on meadow fescue, orchardgrass, and red clover toward the development of new cultivars with value-added traits.
Eastern gamagrass is an effective alternative feedstuff for limiting excessive weight gain in replacement dairy heifers. Dairy heifers consuming diets that contain significant proportions of corn silage or other high-energy forages often gain excessive weight, which negatively affects their future performance as lactating cows. Consequently, dairy farmers and nutritionists will add high-fiber feeds, such as straw, to limit voluntary intake and caloric density for replacement dairy heifers. Chief benefits include: i) may provide an alternative to purchasing ($150/ton) and processing straw; ii) can be easily ensiled and blended into mixed forage diets; iii) eliminates undesirable feed-sorting behaviors by heifers; iv) potentially neutralizes variations in growth performance among penmates because less aggressive heifers can access the proper diet whenever they reach the feedbunk; and v) is effective in reducing the caloric density and dry matter intake of alfalfa/corn silage diets. These factors provide heifer growers with an effective alternative management strategy for managing weight gains by replacement dairy heifers, especially when facilities are overcrowded.
Preservatives for alfalfa hay not as economical with large-round bales. Past studies have shown that, to reduce spontaneous heating and the damage it does to forage quality with alfalfa hay packaged in small (80-lb) rectangular bales, there are clear benefits from applying propionic acid-based preservatives. However, the effectiveness of these products within large hay packages was unclear. ARS researchers at Marshfield, Wisconsin, tested this practice on large-round bales (5-foot diameter) of alfalfa hay packaged at moisture concentrations ranging from 10.2 to 40.4%. They found that although normal heating characteristics were clearly altered by acid treatment, overall positive effects on post-storage nutritional value were limited, and the potential to improve forage quality relative to the cost of application was not especially favorable. Propionic acid-based preservatives only minimally improve storage characteristics within large, round bales. Producers should seek other cost-effective alternatives for preserving large, round bales, such as adequate field drying prior to baling, or the use of oxygen-exclusion methods, such as wrapping bales in plastic.
A better way to assess the productivity of grasses for rotational grazing systems. A wide variety of cool-season grasses can be used by dairy producers in rotationally-grazed pastures. It is generally thought that the most productive grasses support the greatest milk production. Productivity, however, is typically assessed at a mature stage of growth, while these grasses are usually grazed when immature. This manner of assessing productivity may not accurately reflect their value in a rotational grazing system. ARS researchers at Madison, Wisconsin, demonstrated that a more appropriate measure of grass productivity for rotational grazing is the quantity and quality of the leaf portion and how its production is distributed throughout the growing season. Compared to the other grasses evaluated, the leaf production and superior nutritive value of meadow fescue provided slightly lower potential stocking rate but increased simulated milk production 4 to 8 pounds per cow per day, resulting in greater milk production per unit of land.
Conaghan, P., Casler, M.D. 2011. A theoretical and practical analysis of the optimum breeding system for perennial ryegrass. Irish Journal of Agricultural Research. 50:47-63.
Zhang, Y., Zalapa, J.E., Jakubowski, A.R., Price, D.L., Acharya, A., Wei, Y., Brummer, E.C., Kaeppler, S.M., Casler, M.D. 2011. Natural hybrids and gene flow between upland and lowland switchgrass. Crop Science. 51:2626-2641.
Price, D., Salon, P., Casler, M.D. 2012. Big bluestem gene pools in the Central and Northeastern United States. Crop Science. 52:189-200.
Jakubowski, A., Casler, M.D., Johnson, R.C., Hu, J., Jackson, R. 2011. Genetic diversity and population structure of Eurasian populations of reed canarygrass: cytotypes, cultivars, and interspecific hybrids. Crop and Pasture Science. 62:982-991.
Casler, M.D., Tobias, C.M., Kaeppler, S.M., Buell, R., Wang, Z., Cao, P., Ronald, P. 2011. The switchgrass genome: tools and strategies. The Plant Genome. 4:273-282.
Bass, A.E., Philipp, D., Coffey, K.P., Caldwell, J.D., Rhein, R.T., Young, A.N., Coblentz, W.K. 2011. Chemical composition, intake by sheep, and in situ disappearance in cannulated cows of bermudagrass hayed at two moisture concentrations and treated with a non-viable lactobacillus-lactic acid preservative. Animal Feed Science And Technology. 171:43-51.
Coblentz, W.K., Bertram, M.G. 2011. Effects of a propionic acid-based preservative on storage characteristics, nutritive value, and energy content for alfalfa hays packaged in large, round bales. Journal of Dairy Science. 95:340-352.
Coblentz, W.K., Bertram, M.G., Martin, N.P., Berzaghi, P. 2012. Planting date effects on the nutritive value of fall-grown oat cultivars. Agronomy Journal. 104:312-323.
Martinson, K., Coblentz, W.K., Sheaffer, C. 2011. The effect of harvest moisture and bale wrapping on forage quality, temperature, and mold in orchardgrass hay. Journal of Equine Veterinary Science. 31:711-716.
Brink, G.E., Casler, M.D. 2012. Yield and nutritive value differences among cool-season grasses. Forage and Grazinglands. DOI:10.1094/FG-2012-0619-01-RS.
Casler, M.D., Mitchell, R., Vogel, K.P. 2012. Switchgrass. In: Kole, C., Joshi, C.P., and Shonnard, D.R., editors. Handbook of Bioenergy Crop Plants. Boca Raton, FL: CRC Press, Taylor and Francis Group. p. 563-590.
Jakubowski, A.R., Casler, M.D., Jackson, R.D. 2011. Has selection for improved agronomic traits made reed canarygrass invasive? PLoS One. 6(10):e25757. DOI:10.1371/journal.pone.0025757.