Bulletin #9644, Nutritive Value of Ensiled Leaves from Selected Maine Tree and Shrub Species for Forage Production
By Jaime Garzon, Assistant Extension Professor and Forage Educator, University of Maine Cooperative Extension
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Note: The data in this bulletin describe the trees and shrubs at the sites harvested for livestock trials under SARE FNE22-013; single specimens of other tree and shrub species were also tested. The nutritive value of leaves from tree and shrub stands varies due to many factors, including health, age, regrowth period, soil qualities and contents, sun exposure, and weather. There was no research design for regional sampling; therefore, conclusions, predictions, or deductions based on this information should be avoided.
Introduction
Maine’s agricultural operations encompass large areas of forested land. Agricultural operators have observed that cattle, sheep, and goats occasionally consume tree leaves without exhibiting signs of intoxication. In Europe, the tree species may be similar but are not identical to those found in the northeastern United States. Historically, European tree leaf harvests during summer and fall have provided substantial forage for wintering livestock (Austad & Hauge 2013, Logan 2019, Machatschek 2002, Read 2003, Slotte 2000, Watkins 2014).
Thus, the goal of this bulletin is to provide new information on the nutritive value of fresh and ensiled tree and shrub leaves from common Maine species, addressing an informational gap that hinders livestock farmers from effectively utilizing on-site woody perennial forages when weather challenges disrupt their grass-forage harvests.
Methodology and variables evaluated
Three primary harvest locations were:
- Maine Organic Farmers and Gardeners Association. Unity (ME).
44° 35’ 23.3” N; 69° 17.25’ 25.7” W. - Y Knot Farm. Belmont (ME).
44° 24’ 24.25” N; 69° 06’ 7.3” W. - Faithful Venture Farm. Searsmont (ME).
44° 24’ 53.5” N; 69° 13’ 1.7” W
Leaves were stripped from cuttings (up to 3 ½” D butts) using a prototype chain-flail leaf separator developed by current SARE FNE24-083 technical advisor Karl Hallen; this method was 90% faster than traditional hand-stripping. Using hand-held power tools for cutting and the machine prototype for leaf stripping produced over 2,500 gallons of tree and shrub leaf silage in 1,000 linear feet of field edges (Figure 1).
Photo: Courtesy of Shana Hanson
Field-edge sites were chosen based on truck access to park the leaf separator for stationary use next to cutting activities. Leaf-silage yields per location and labor time were measured and reported in the SARE FNE22-013 Final Report. Leaf-bearing material was harvested regeneratively from field edges by coppicing most shrubs and some trees, thinning trees to a spacing of 10 feet, and pollarding the remaining trees (cutting above browse height, primarily with a nine-foot pole chainsaw). An exception was Faithful Venture Farm, where the trees were well established. There, existing tree structures were drastically pruned but preserved. All harvests aimed to establish 3-to-8-year cycles.
All tree and shrub species present were harvested, container-ensiled, and fed to livestock (cattle, sheep, and goats) during winter. The intake trial, animal preference, and effects on milk yield are reported in the SARE FNE22-013 Final Report.
Barrels were packed by armloads from the bin (Figure 2) and were not always completely full; therefore, compaction varied but did not appear to have any consequence due to reliable container seals. Fermentation time varied from one to four months (after which winter temperatures slowed activity). An exception occurred for 2022 samples, as some were fed more than a year after harvest.
Photo: Courtesy of Shana Hanson
Freshly separated leaf matter was sampled from the bin under the leaf separator and then frozen. Ensiled leaf matter was collected from sealed plastic barrels or buckets during feed-out to livestock in winter and frozen. Crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), water-soluble carbohydrates (WSC), total digestible nutrients (TDN), and relative feed value (RFV) were assessed for both frozen fresh and ensiled samples through NIR analyses at the DairyOne® lab.
Results
Tables 1 and 2 present the nutritive value results for 18 species. Nine out of the 28 species in the SARE FNE240-083 project yielded incomplete and/or highly variable results. Box elder was excluded, as it is sometimes toxic to livestock.
The ensiling process decreased the mean values of CP, WSC, and TDN while increasing ADF and NDF (Table 2). These changes can be attributed to the fermentation process, during which microorganisms utilize soluble carbohydrates as an energy source and modify protein sources.
Basswood and black locust retained a higher CP concentration after fermentation than other species, with 3.6 – 5.3% WSC and 61% TDN (Table 2). It is important to note that high-quality forage is expected to have 15-25% crude protein, 15-30% ADF, 40-60% NDF, 7-10% WSC, and 60-70% TDN. Therefore, the average nutritive value of all materials after the ensiling process falls within these ranges.
Fresh leaves exhibited higher values of CP, WSC, and TDN (Table 1). However, tree leaves may contain antinutritional components such as alkaloids, tannins, or cyanogenic acids. These compounds are typically broken down through anaerobic silage fermentation, making it preferable to provide ensiled foliage instead of fresh leaves for animals. The fermentation process during ensiling can enhance palatability and animal preference while reducing the risk of poisoning.
Notes:
Do not harvest leaves for silage on bare soil for sheep and goat’s intake. Soil from uprooted roots can be a source of listeria in corn and grass silages; it remains uncertain whether listeria from the soil will thrive in tree and shrub materials.
Feeding large quantities of ensiled foliage to monogastric or sensitive animals such as poultry or horses is not recommended. These animal species are more vulnerable to poisoning due to their lack of a rumen. Europe literature on traditions has reported hog intake of ensiled foliage (Machatschek 2002), which may suggest some adaptation of these breeds to certain tree and shrub-fermented foliage. Hogs in SARE FNE18-897 (Hanson 2020) found most Waldo County tree species palatable, fresh, dried or ensiled, but did not test intake levels
SARE FNE24-083 is an ongoing research project, so new results are expected to be included in this bulletin in the near future.
Acknowledgements
The University of Maine Cooperative Extension thanks Shana Hanson for providing the data and photos that comprise this bulletin’s results.
Funding
This project was funded by Northeast Sustainable Agriculture Research and Education through FNE22-013 and FNE24-083 Farmer Grant awards. Northeast SARE is funded by the National Institute of Food and Agriculture (NIFA).
References and other sources
- Austad, I. & Hauge, L. (2014). Trær og tradisjon. Bruk av lauvtrær i kulturlandscapet. (Trees and tradition: Use of leaf-trees in the cultural landscape.) Fagbokforlaget. ISBN: 978-82-11-01905-9.
- Chin J. (2022). The potential use of tree leaf silage for livestock nutrition, including willow, drumstick, mulberry, and acacia species. Thesis. University of Maine. digitalcommons.library.umaine.edu/honors/719/.
- Gabriel S. (2021). Quantifying nutritional value and best practices for woody fodder management in ruminant grazing systems. Project FNE19-30. Northeast Sustainable Agriculture Research and Education. projects.sare.org/project-reports/fne19-930/
- Hanson S. (2025) A closer look to guide farm use of tree/shrub silages: Per-species & ensilement analyses for safe, nutritious rationing, plus replicable trial results. Project FNE24-083. Northeast Sustainable Agriculture Research and Education. projects.sare.org/project-reports/fne24-083/.
- Hanson S. (2024). Efficient leaf-dense tree/shrub silage production from field edges: Climate-resilient winter forage supplement for cattle, sheep, and goats. Project FNE22-13. Final Report. Northeast Sustainable Agriculture Research and Education. projects.sare.org/project-reports/fne22-013/.
- Hanson, Shana (2020). Tree Leaf Fodder for Livestock; Transitioning Farm Woodlots to “Air Meadow” for Climate Resilience.” Project FNE22-13. Final Report. Northeast Sustainable Agriculture Research and Education. projects.sare.org/project-reports/fne18-897/.
- Logan, William Bryant (2019). Sproutlands: Tending the Endless Gift of Trees. W. W. Norton & Company, NY. ISBN 978-0-393-609-417
- Machatschek, Michael (2002). Laubgeschichten (foliage stories); Gebrauchswissen einer alten Baumwirtschaft, Speise – und Futterlaubkulture. Wien, Bohlau. 542pp.
- Read, Helen J. (2003). A study of practical pollarding techniques in northern Europe; Report of a three-month study tour, August to November 2003. Sent on CD by the author, 2011. PDF accessible from google.com by title search March 1, 2021, posted by ancienttreeforum.org.uk.
- Slotte, Håkan (2000). Lövtäkt i Sverige och på Åland; Metoder och påverkan på landskapet. Uppsala: Acta Univeritatis Agriculturae Sueciae, Swedish University of Agricultural Sciences (Agraria 236).
- Watkins, Charles (2014). Trees, Woods and Forests: A Social and Cultural History. TJ Internationl, Padrow, Cornwall, Great Britain. ISBN 978-1-78023-373-4
Table 1. Nutritive value of fresh leaves from 19 tree and shrub species in Maine.
| TREE AND SHRUB SPECIES | Crude protein (%) | Acid detergent fiber (%) | Neutral detergent fiber (%) | Water soluble carbohydrates (%) | Total digestible nutrients (%) | Relative feed value |
|---|---|---|---|---|---|---|
| American beech | 12.3 | 31.0 | 52.6 | 7.7 | 64.0 | 115 |
| American elm | 11.1 | 23.1 | 53.4 | 8.3 | 58.0 | 124 |
| Arrowwood | 12.0 | 31.4 | 43.0 | 9.4 | 68.0 | 139 |
| Basswood | 19.4 | 24.0 | 42.6 | 9.5 | 65.0 | 163 |
| Big toothed aspen | 9.8 | 27.1 | 38.8 | 14.0 | 72.0 | 176 |
| Black cherry | 17.0 | 25.6 | 34.9 | 9.1 | 67.5 | 174 |
| Black locust | 17.1 | 25.5 | 36.9 | 10.0 | 67.0 | 203 |
| Gray birch | 14.1 | 30.7 | 43.0 | 6.8 | 72.0 | 146 |
| Green ash | 15.4 | 26.9 | 43.3 | 8.3 | 66.0 | 134 |
| Honeysuckle | 11.1 | 29.9 | 45.0 | 13.6 | 65.0 | 173 |
| Leatherwood | 9.5 | 27.0 | 36.5 | 16.5 | 72.0 | 205 |
| Norway maple | 12.0 | 23.6 | 41.0 | 9.3 | 68.0 | 281 |
| Red maple | 10.9 | 16.8 | 25.1 | 18.0 | 79.0 | 97 |
| Red oak | 15.6 | 27.3 | 40.4 | 6.6 | 61.0 | 126 |
| Rock maple | 11.0 | 18.7 | 32.5 | 20.1 | 69.0 | 209 |
| Smooth buckthorn | 14.3 | 20.3 | 32.5 | 15.3 | 70.0 | 308 |
| White ash | 9.9 | 25.1 | 37.1 | 7.6 | 66.0 | 145 |
| Winterberry | 11.7 | 27.6 | 43.4 | 9.6 | 69.0 | – |
| AVERAGE | 13.1 | 25.5 | 39.7 | 10.9 | 67.8 | 170 |
| Standard deviation | 2.7 | 3.9 | 6.7 | 4.0 | 4.4 | 54 |
Table 2. Nutritive value of ensiled leaves from 19 tree and shrub species in Maine.
| TREE AND SHRUB SPECIES | Crude protein (%) | Acid detergent fiber (%) | Neutral detergent fiber (%) | Water soluble carbohydrates (%) | Total digestible nutrients (%) | Relative feed value |
|---|---|---|---|---|---|---|
| American beech | 12.7 | 35.8 | 55.6 | 2.9 | 59.0 | 102 |
| American elm | 12.1 | 23.7 | 54.0 | 4.3 | 54.0 | 121 |
| Arrowwood | 12.8 | 36.2 | 49.7 | 5.1 | 60.0 | 114 |
| Basswood | 19.8 | 24.8 | 45.3 | 3.6 | 61.0 | 143 |
| Big toothed aspen | 10.8 | 28/3 | 39.6 | 8.7 | 61.0 | 157 |
| Black cherry | 13.5 | 22.2 | 30.0 | 8.8 | 64.2 | 232 |
| Black locust | 17.3 | 26.6 | 37.3 | 5.3 | 61.0 | 170 |
| Gray birch | 11.6 | 31.9 | 44.4 | 8.2 | 63.0 | 133 |
| Green ash | 12.8 | 28.4 | 40.9 | 8.3 | 59.8 | 165 |
| Honeysuckle | 11.2 | 25.8 | 36.6 | 12.0 | 64.6 | 156 |
| Leatherwood | 8.7 | 32.4 | 43.2 | 13.9 | 66.0 | 137 |
| Norway maple | 12.8 | 24.0 | 42.8 | 4.8 | 65.0 | 153 |
| Red maple | 10.0 | 23.5 | 33.3 | 14.5 | 68.8 | 220 |
| Red oak | 14.3 | 29.0 | 46.3 | 4.1 | 60.3 | 134 |
| Rock maple | 9.5 | 22.9 | 34.1 | 14.3 | 66.0 | 194 |
| Smooth buckthorn | 15.4 | 25.9 | 38.9 | 6.5 | 67.0 | 164 |
| White ash | 11.1 | 26.8 | 39.2 | 8.4 | 59.3 | 161 |
| Winterberry | 12.6 | 31.4 | 49.2 | 4.0 | 62.0 | 122 |
| AVERAGE | 12.9 | 27.5 | 41.7 | 7.5 | 62.7 | 157 |
| Standard deviation | 2.7 | 4.2 | 7.0 | 3.7 | 3.8 | 35 |
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