Does Clover Have Tannins? The Surprising Truth

December 2, 2025 •

2 min read

While many assume clover is tannin-free, research shows that some parts of the plant, particularly the flowers, do contain condensed tannins. The specific concentration of tannins depends heavily on the clover species, variety, and the part of the plant in question, challenging the long-held belief that it is entirely devoid of these compounds.

Quick Summary

This article explores the presence of tannins in various clover types, detailing where they are found and how breeding efforts have altered tannin content. It also covers the significant impacts of these compounds on livestock health, particularly regarding bloat prevention and greenhouse gas emissions, contrasting different clover varieties.

Key Points

Clover contains tannins, but primarily in the flowers, not the leaves: Traditional white and red clovers have very low condensed tannin levels in their leaves, but higher concentrations are found in their flower heads.
Low leaf tannins increase bloat risk in ruminants: The lack of significant tannins in the leaves of conventional clover varieties is a major contributor to pasture bloat in livestock.
Genetically modified clover has tannins in its leaves: High-condensed-tannin (HiCT) white clover varieties have been engineered to express significant levels of tannins in their foliage to reduce bloat and methane emissions.
Tannins in clover improve animal and environmental health: The addition of tannins through HiCT clover improves protein absorption, reduces methane emissions, and mitigates internal parasites in livestock.
Red clover manages protein differently than tannin-rich plants: While not high in condensed tannins, red clover contains polyphenol oxidase (PPO), an enzyme that helps reduce protein degradation and bloat risk through a different mechanism.

Understanding Tannins in Forage

Tannins are naturally occurring polyphenolic compounds found in many plants. In forage, they can significantly impact how efficiently livestock digest their feed by binding and precipitating proteins.

The Clover and Tannin Paradox

Traditional pasture legumes like white clover and red clover were long considered to have very low tannin levels in their leaves compared to other legumes, which contributes to bloat in ruminants. When ruminants consume high-protein clover, rapid protein breakdown in the rumen can cause stable foam that leads to potentially fatal bloat.

The Presence of Tannins in Specific Clover Parts

While leaves of standard white and red clover typically lack significant tannins, research shows that other parts, especially flowers and certain leaf tissues, do contain these compounds. White clover flowers have high concentrations of condensed tannins (CTs), specifically prodelphinidins. The presence of tannins in these specific plant parts serves as a natural defense mechanism.

Modern science has addressed the limitations of traditional clovers. Genetically modified varieties of white clover have been developed to express biologically significant levels of condensed tannins in their leaves. This involves activating a dormant genetic switch, enabling tannin production throughout the foliage.

Benefits and Implications of High-Tannin Clover

Introducing tannins directly into forage through high-tannin (HiCT) clover varieties offers several benefits for ruminant livestock:

Bloat Prevention: Tannins bind to proteins, preventing the rapid breakdown that causes bloat.
Improved Protein Utilization: By protecting proteins in the rumen, tannins allow more efficient absorption in the small intestine, enhancing feed efficiency and production.
Reduced Methane Emissions: Tannins can alter rumen fermentation, reducing methane emissions.
Enhanced Animal Health: Tannins may also help control internal parasites.

Comparison of Tannin Content in Clover Types

The table below compares the approximate tannin expression across different clover and legume types. Note that levels can vary based on cultivar and growing conditions.


Feature	Standard White Clover (Leaves)	Genetically-Enhanced HiCT White Clover (Leaves)	Birdsfoot Trefoil (Leaves)	Red Clover (Leaves)
Tannin Level	Negligible	Biologically significant (>1.5% of DM)	High (effective for bloat prevention)	Negligible in leaves (PPO enzyme offers a different mechanism)
Effect on Bloat	High risk	Low risk	Low risk	Low risk due to PPO enzymes, not tannins
Protein Digestion	Rapid breakdown in rumen	Improved utilization in intestines	Improved utilization in intestines	Improved utilization due to PPO
Methane Impact	No reduction	Significant reduction	Significant reduction	Not tannin-related
Agronomic Persistence	High persistence	Good persistence after breeding efforts	Often poor persistence under intensive grazing	Good persistence

Conclusion

Clover does contain tannins, but their presence varies by variety and plant part. Traditional white and red clover leaves have minimal tannins, contributing to bloat risk, though their flowers do contain them. Notably, genetically engineered clover varieties now successfully incorporate tannins into their leaves, offering significant advantages for animal health and the environment. These advancements demonstrate the complex relationship between plant compounds and agricultural practices.

For more in-depth scientific research on this topic, consider reading the full study on genetic modifications in white clover for condensed tannin expression, published in Frontiers in Plant Science.

Frequently Asked Questions

While the leaves of common white and red clover contain negligible amounts, the flowers (inflorescences) of white clover have relatively high concentrations of condensed tannins.

The tannins in traditional white clover are concentrated in the flowers, which are not always consumed. The leaves, which are the main forage, contain insufficient tannins to inhibit the foaming that causes bloat.

Yes, scientists have genetically engineered varieties of white clover to express high levels of condensed tannins directly in their leaves, addressing the bloat and environmental issues associated with traditional clover forage.

Tannins bind to proteins in the rumen, preventing bloat, improving protein utilization by the animal, and reducing harmful methane emissions. This also helps reduce the burden of internal parasites.

Red clover, like white clover, has low levels of condensed tannins in its leaves. However, it contains the enzyme polyphenol oxidase (PPO) which provides similar protein protection benefits, albeit through a different process.

High-tannin clover varieties are generally developed from existing commercial clovers, such as a cultivar of white clover. Field trials have shown that with proper breeding, they can have commercially acceptable yield and persistence, fitting into existing agricultural systems.

Yes, studies have shown that feeding livestock high-tannin clover can significantly reduce methane emissions produced during ruminal fermentation. Some research suggests potential reductions exceeding 15%.