Optimal Nutritive Value of Honeylocust Seed Pods Within Temperate Silvopasture

View the project final report

• 2009 annual report

Commodities

• Additional Plants: ornamentals

Practices

• Education and Training: extension, participatory research
• Natural Resources/Environment: habitat enhancement
• Production Systems: agroecosystems, integrated crop and livestock systems

Seed pods from high-sugar varieties of honeylocust (Gleditsia triacanthos L.) trees have potential as an animal feed supplement from late fall to mid-winter. However, data regarding yields and variation in nutritive characteristics of pods from improved honeylocust varieties such as ‘Millwood’ are limited. Furthermore, the degradation of pods over time as it affects the supply of high quality fodder for ruminants grazing within silvopastures is unreported. A study was conducted within an active honeylocust silvopasture to: 1) determine seedpod yields of Millwood honeylocust trees managed within silvopastures, 2) estimate the nutritional variability of seed pods among Millwood honeylocust trees, and 3) determine changes in fodder nutritive value over time. In October 2008, 2009, and 2010, seedpod yields were estimated using both visual classification and pod-harvests from representative trees. In 2008 and 2009, 12 randomly-sampled pods were collected from each pod-bearing Millwood tree to determine the variability in fodder nutritive value among trees. Additional Millwood and wild-type seedpods were placed in in-situ bags and allowed to decompose within silvopastures over time. At monthly intervals from November to March, in-situ samples were collected and analyzed for nutritive value. Levels of digestibility, neutral and acid detergent fibers, acid detergent lignin, and crude protein were characterized. Ground Millwood seedpods were comparable to whole-ear dent corn in terms of nutritive value. Both ground pods and seeds were highly digestible (78.7 and 96.3%, respectively) and low in fiber and lignin. Seeds, with over 20% CP, have potential as a CP supplement. Millwood trees displayed alternate bearing patterns with 3-yr average dry matter yields of approximately 12 kg tree-1. Since honeylocust pods represent a potential high-quality feed resource for ruminants, studies characterizing their nutritive value and degradation may influence management decisions regarding their utilization within silvopastures.

Project Relevance to Sustainable AgricultureOur project has four main objectives:
1) Determine yields and year-to-year variation of Millwood honeylocust pod production for trees managed within active silvopastures
2) Estimate the nutritional variability of pods produced from Millwood honeylocust trees managed in a silvopasture.
3) Determine changes in husk and seed nutritive value and digestibility from three distinct honeylocust tree types over time after pod drop
4) Characterize changes in pod development and nutritive value through the growing season and to determine their relationship to time of pod drop.

We hypothesized that honeylocust silvopasture systems with immature trees could produce pods of sufficient yield and quality to provide financial benefit for land managers. Further, we hypothesized that nutritive value of honeylocust seed pods varies by tree type (i.e., by genetic origin) and by time (through the periods of pod development and decay), and that decay may improve digestibility of hard-coated honeylocust seeds for some livestock species. Time of peak nutritional value for different tree types also could be determined to optimize honeylocust utilization within silvopasture systems.