Location: Dairy Forage Research2009 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
Field studies evaluating eastern gamagrass and fall-seeded cereal grains are entering their third year of evaluation, and summaries and preparation of manuscripts will begin at the close of the growing season. Extensive analysis and manuscript preparation have been initiated during FY09 for hay preservation studies. Pasture and greenhouse experiments were initiated to support objectives related to optimization of pasture management schemes. Field samples were collected from established experiments to support genetic studies of lignin and etherfied ferulates, selection studies for frost-seeding ability, and silage preservation studies. Meadow fescue phytogeographic studies have been completed and are moving into the analysis and summarization phase. Meadow fescue seed was produced in preparation for extensive field trials. Work assessing polyphenol and forage management impacts on forage protein utilization continued in 2009. After identifying appropriate rates of growth regulators for controlling alfalfa growth, a field experiment examining alfalfa interseeding into corn was continued in 2009.
1. Nutritive value and sward structure influence pasture utilization. The quantity of herbage produced by a pasture is generally considered the primary criteria influencing intake of grazing cattle. In pastures that are rotationally grazed by high-producing dairy cattle however, forage availability generally exceeds the daily requirement of the cow, and intake may be affected by other factors. Research with four diverse temperate grasses demonstrated that the quantity of the leaf fraction and its position within the sward canopy relative to the less palatable stem fraction often governed herbage consumption. When there were no differences in the canopy leaf structure, pasture utilization was positively correlated with herbage nutritive value. The results provide guidelines for the selection and management of temperate grasses in rotational grazing systems.
2. Modified cutting management improves degradable protein concentrations in red clover. Excessive protection of red clover protein from proteolysis by o-quinones limits protein digestion and adsorption by cattle and the production of milk. The primary objective of this study was to evaluate how cutting management influences the dry matter yield and protein quality of red clover harvested for feeding to dairy cattle. We found that commencing red clover harvests earlier than normal in the spring favorably increased rumen degradable protein concentrations and decreased the proportion of protein protected by o-quinones. Fortunately, earlier cutting did not hurt total yearly forage production or survival of red clover plants. Implementing these harvest management practices may improve milk production of cattle fed red clover and decrease the need for feeding expensive protein supplements.
3. Spontaneous Heating in Large Bale Packages Increases Losses of DM and Reduces Forage Digestibility. Spontaneous heating in hay, generally caused by too much moisture in the plant at the time of baling, costs livestock producers in terms of dry matter losses (less hay to feed) and forage quality. Spontaneous heating may also lead to spontaneous combustion and a resulting fire. With conventional small rectangular bales (80 to 100 pounds), a positive linear relationship between moisture content and heating has been clearly established; as moisture increases, so does the amount of heating. Currently, forage producers typically use much larger round or square bales, and these larger hay packages have not been studied extensively with respect to spontaneous heating. A study was conducted to determine if the size of bale (3-, 4-, or 5-foot diameter) had an impact on spontaneous heating at different moisture levels. Subsequently, the amount of dry matter lost and the digestibility of the damaged forages also were measured. We observed that large-diameter bales were more likely to exhibit spontaneous heating at relatively low moisture contents (<20%). Also, the amount of feed lost increased linearly with the amount of spontaneous heating in the bales, while forage digestibility decreased at low to moderate levels of heating, but then stabilized thereafter. This study also confirmed that current measures of spontaneous heating are consistently effective indicators of dry matter loss and forage digestibility. This work will encourage forage producers to be more aware of moisture content when producing larger bales, which are far more likely to heat spontaneously than traditional 80 to 100-lbs bales. It also gives livestock producers and nutritionists more confidence when using measures of spontaneous heating to predict associated effects on forage quality and digestibility when balancing rations.
4. Spontaneous Heating in Large Bale Packages Increases Forage Fiber Components, but Has Limited Effects on Fiber Digestibility. Spontaneous heating in hay, generally caused by too much moisture in the plant at the time of baling, costs livestock producers in terms of dry matter losses (less hay to feed) and forage quality. Most livestock producers and nutritionists are familiar with how protein is damaged or lost when bales experience spontaneous heating; however, this is not necessarily the most important negative consequence. The loss of energy, due to the rapid oxidation of sugars during the microbial respiration that causes heating, significantly affects feed quality and value, too. This also increases the percentage of fiber in the forage; but little research has looked specifically at how spontaneous heating affects fiber components, composition, and digestibility. This study showed that: i) concentrations of all fiber components increased in response to spontaneous heating during storage; and ii) surprisingly, fiber digestibility was largely unaffected by heating characteristics except within bales incurring the most extreme levels of heating. Although the rate of ruminal fiber disappearance was decreased by as much as 40% by spontaneous heating, estimates of ruminal fiber disappearance were largely unaffected. This research will aid nutritionists in the evaluation and appropriate use of heat-damaged hays for dairy cows and replacement heifers.
Brink, G.E., Casler, M.D. 2009. Meadow Fescue, Tall Fescue, and Orchardgrass Response to Nitrogen Application Rate. Forage and Grazinglands. Available: http://www.plantmanagementnetwork.org/sub/fg/research/2009/rate/.