Location: Dairy Forage ResearchTitle: Fermentation and chemical composition of high-moisture lucerne leaf and stem silages harvested at different stages of development using a leaf stripper
|SIKORA, MIRANDA - Oak Ridge Institute For Science And Education (ORISE)|
|HATFIELD, RONALD - Retired ARS Employee|
Submitted to: Grass and Forage Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2019
Publication Date: 4/16/2019
Citation: Sikora, M.C., Hatfield, R.D., Kalscheur, K. 2019. Fermentation and chemical composition of high-moisture lucerne leaf and stem silages harvested at different stages of development using a leaf stripper. Grass and Forage Science. 74(2):254–263. https://doi.org/10.1111/gfs.12423.
Interpretive Summary: The goal of this study was to find whether a new technology (a leaf stripper) could be used in alfalfa production to decrease the number of harvests in a growing season while maintaining or improving the nutritional value of the feed. The frequent harvests required for alfalfa decreases the likelihood a farmer would plant this otherwise valuable protein source. In addition, alfalfa is a perennial plant and provides many environmental benefits such as capture of nutrient run-off and preventing soil erosion. We found that when the leaf stripper was used to produce silages of leaf material and silages of stem material that leaf silage had greater animal available protein in all development stages of alfalfa. Stem silages can be used for cows that do not need a high protein diet such as dry cows. This suggests that farmers could harvest later which would reduce the number of harvests and still produce a high-value feed. In turn, farmers in the dairy industry may grow more alfalfa to meet their cows’ needs while benefiting the environment.
Technical Abstract: Lucerne (Medicago sativa L.) requires four or more cuttings at early bud stage per growing season to optimize the amount of crude protein and digestible fibre for feeding high-producing dairy cows. However, there is potential to generate a nutrient-dense feed from lucerne regardless of developmental stage by harvesting its protein-rich leaves separate from its fibrous stems. In order to determine whether fractionated lucerne can be effectively ensiled under high-moisture conditions and be nutritionally competitive with wilted whole-plant silage, leaf and stem fractions, harvested at three developmental stages (early bud, 10-20% bloom and >50 % bloom), were directly ensiled in mini-silos. At day 0, 1, 3, 21 and 140 of ensiling, silages were analyzed for protein and non-protein nitrogen fractions as well as their fermentation products and carbohydrate composition. Silages from unwilted leaves and stems were more heterofermentative than wilted whole-plant silages; their fermentation shifted from primarily lactic acid to acetic acid production after 21 days. In leaf silages, the high degree of protein degradation into non-protein nitrogen (~55%) was most likely due to fermentation quality. Nevertheless, at 140 days of ensiling, leaf silages had 21-25% higher (p < 0.01) available protein (peptide amino acids, soluble and insoluble protein) content than wilted whole-plant silages, regardless of developmental stage. Achievement of a more rapid pH decline and improved fractionation may further increase the nutritional value of leaf silages.