Concentration and composition of condensed tannins in leaves from fodder trees and shrubs in Pakistan

Authors: ROOMI, ISHRAT - Karakoram International University; Zeller, Wayne; Akins, Matthew; HUSSAIN, AZHAR - Karakoram International University

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/30/2025
Publication Date: 4/21/2026
Citation: Roomi, I., Zeller, W.E., Akins, M., Hussain, A. 2026. Concentration and composition of condensed tannins in leaves from fodder trees and shrubs in Pakistan. Journal of Agricultural and Food Chemistry. https://doi.org/10.1002/jsf2.70028.
DOI: https://doi.org/10.1002/jsf2.70028

Interpretive Summary: Agricultural systems in many countries of the world suffer from lack of adequate access to high quality feedstuffs required for proper maintenance and production of ruminant animals. The development of methods or techniques to improve the nutritional quality of feedstuffs in these agricultural systems is highly desired. Condensed tannins are chemical compounds contained in plant materials which have a high propensity for binding to proteins. Condensed tannins contained in forage and fodder have shown the ability to complex forage protein in the rumen, protecting it from rapid degradation during rumen fermentation and increasing the delivery of true protein to the hind gut, resulting in improved health and productivity of ruminant animals. This study analyzed condensed tannin content of leaves from four fodder trees and two shrubs common in the Hopper Valley region of Pakistan. Leaves from Salix nigra (black willow), Salix alba (white willow), Populus nigra (black poplar), Elaeagnus angustifolia (Russian olive), Hippophae rhamnoides (sea buckthorn), and Rosa webbiana (Webb’s rose) collected from three distinct locations in the region and across three different seasons (spring, summer and fall) were dried and ground for the analysis. The condensed tannin content of both Salix species increased with seasonal growth but decreased in Populus nigra and Hippophae rhamnoides across all three locations tested. Insignificant levels of condensed tannins were detected in Elaeagnus angustifolia and Rosa webbiana. Salix nigra and Salix alba likely contain proper condensed tannin levels to bolster nitrogen use efficiently in ruminants without exhibiting a detrimental effect on dry matter intake. The results of this study suggest that the greatest impact on ruminant nutrition would be when the Salix species leaves are harvested in the fall and the Populus nigra and Hippophae rhamnoides leaves were harvested in the spring. Following these recommendations, producers will likely exploit the benefits of these condensed tannin-containing fodder species to maximize use of the protein present in these feedstuffs.

Technical Abstract: The lack of dependable, high-quality forage and animal feedstuffs in many areas of the world hampers livestock production. In these regions, farmers often rely on native fodder tree and shrub leaves as a forage source for their animals with little or no information available on nutritional factors of these feedstuffs. In addition, there is a growing need to improve nitrogen use efficiency (NUE) in ruminants, especially in agricultural areas where livestock feedstuffs are limited in quantity and of lower quality. Condensed tannins (CTs) show capability of protecting protein from degradation during both the ensiling process and rumen digestion, producing greater rumen undegradable protein translating into higher ruminant livestock productivity. Determination of the concentration of CTs in the leaves of four fodder tree species (Salix nigra, Salix alba, Populus nigra, and Elaeagnus angustifolia), and two shrub species (Hippophae rhamnoides and Rosa webbiana) across seasons from three locations in Pakistan is detailed below. The highest levels of CTs were found in S. nigra and S. Alba (seasonal averages of 17.9 and 18.5 mg/g, respectively) and were targeted for purification and characterization. 1H–13C heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectra of purified CTs indicated the following composition for S. nigra, procyanidin/prodelphinidin ratio = 59/41; cis/trans ratio = 59/41; estimated mean degree of polymerization (mDP) = 8.1. For S. alba, procyanidin/prodelphinidin ratio =99/1; cis/trans ratio = 85/15; estimated mDP = 6.9. The CT content of both Salix species trended higher with seasonal growth, with the CT content of S. nigra across seasons statistically significant. The CT content in P. nigra and H. rhamnoides trended lower across all three locations tested but did not reach the level of statistical significance. Insignificant levels of CTs were detected in E. angustifolia and R. webbiana. Based on CT literature reports, S. nigra and S. alba likely contain adequate CT levels to bolster NUE in ruminants without exhibiting a detrimental effect on dry matter intake.