Summary 

Bird's-foot trefoil (Quebec/Eastern Canada)

• What Perennial legume ideal for poorly drained, slightly acid soils.
• Yield & quality Productive especially on heavy soils; very productive in mixtures with grasses (timothy, bluegrass, orchardgrass); optimum quality at early to mid-flowering stage.
• Animal performance Milk up slightly according to rations; good steer gains on pasture; greater safety thanks to absence of bloat.
• Condensed tannins The new feedstuffs: zero bloat when grazing; protect proteins in the rumen, reduce NH₃ and urinary nitrogen, and improve preservation in silage.
• Location & management Slow establishment and sensitive to competition (shallow sowing 1-2 cm, Rhizobium inoculation, sowing with less competitive grasses); 1ʳᵉ late cutting in the year of establishment; then ~6-week interval and 7-10 cm stubble; allow to go to seed every 2-3 years for perenniality.
• Cultivars prostrate (pasture: Empire, Fergus, Leo), semi-erect (mixed use: Dawn, Norcen, Mackinaw), erect (hay: Viking, Maitland).
• For whom For growers in Quebec and Eastern Canada looking for resilience, reliable wetland yields and reduced nitrogen losses.

Bird's-foot trefoil: a legume with multiple benefits for meadows and pastures

Less well known than alfalfa or clover, birdsfoot trefoil (Lotus corniculatus L.) deserves a place of choice in forage systems. Two features set it apart: its tolerance of weakly acidic, poorly drained soils, and the presence of condensed tannins that reduce the risk of bloat while improving nitrogen efficiency and certain silage fermentation parameters.

1) Agronomic profile

A perennial legume 30 to 75 cm high (depending on cultivar and conditions), trefoil has thin stems and therefore a higher risk of lodging than alfalfa and clover. It is more tolerant of slightly acid soils and imperfect drainage conditions, provided that surface ice formation is avoided. Its shallower roots than alfalfa explain its slightly lower drought tolerance. A major advantage for grazing: it does not cause bloat, a key benefit for cattle and sheep.

2) Yield and nutritional value

Comparative performance. Trials in Vermont (pure cultivation) show similar yields between species at first cut, but an advantage for alfalfa at 2nd and 3rd cut. Notable fact: trefoil maintains a stable yield whatever the drainage, while alfalfa expresses its potential better in well-drained soils. Another advantage is that potato leafhopper, a pest of alfalfa, is virtually unaffected by trefoil, which shows almost no damage in evaluations, compared with notable levels in alfalfa and clovers (Darby et al., 2019).

Figure 1 Relationship between legume species and cutting number on dry matter yield (tonne/acre) (Darby et al., 2019).  

Figure 2 Yield in tonnes DM of different types of legumes according to drainage type (Darby et al., 2019).

Table 1 Severity of potato leafhopper damage on a scale of 0 to 5 according to the botanical composition of the meadow at first cut (Darby et al. 2019).

Legume-grass mixtures. In frequent cutting regimes in Quebec and Nova Scotia, trefoil combined with meadow brome or timothy outperformed alfalfa and white clover in the same associations (Bélanger et al., 2018). In mixed grasslands on imperfectly drained soils, this is a strong argument.

Figure 3 Yield measured by the pairing of a legume (birdsfoot trefoil, alfalfa and white clover) and a grass (meadow brome, timothy, tall fescue, Kentucky bluegrass, meadow fescue and orchard grass) under cut-and-graze management (Bélanger et al., 2018).

Nutritional value. Bird's-foot trefoil quality declines more slowly with maturity than alfalfa: its protein content, high but slightly lower than alfalfa's, remains attractive for longer. As with all legumes, protein decreases and fiber increases with phenological age; aiming to harvest at the early to mid-flowering stage maximizes the quality/yield balance while offering a slightly wider cutting window.

Figure 4 Variation in the nutritional value of birdsfoot trefoil as a function of maturity (Undersander et al., 1993).

3) Silage and digestibility

Condensed trefoil tannins modulate fermentation: syntheses indicate that their increase is accompanied by lower concentrations of butyric acid and ammonia (NH₃-N), a sign of reduced nitrogen losses and "cleaner" fermentation (Jayanegara et al., 2018). In the rumen, tannins bind proteins, slowing down their degradation and promoting better nitrogen efficiency (more proteins "escape" the rumen and are digested in the gut).
At high concentrations (> 50 g/kg DM), however, tannins can reduce overall digestibility (Jayanegara & Palupi, 2008). Overall, the digestibility of trefoil organic matter is often slightly lower than that of alfalfa, but this is partly compensated for by better protein utilization and reduced nitrogen losses.

Figure 5 Effects of tannins on butyric acid and ammonia (NH₃-N) in silage (adapted from Jayanegara et al., 2018).

4) Animal performance

Milk. In frequent cuts, work by Agriculture and Agri-Food Canada (Bélanger et al., 2018) shows that rations incorporating birdsfoot trefoil support higher milk production than equivalent rations based on alfalfa or white clover, regardless of the companion grass. In pure crops, several studies report comparable, and sometimes higher, milk production with birdsfoot trefoil or white clover versus alfalfa, without altering the major milk components. The level of tannins counts: with higher (but not excessive) levels, we often observe a slight gain in milk (kg/d), fat (kg/d) and the N-milk/N-ingested ratio.

Figure 6 Estimated milk production based on the pairing of legumes (birdsfoot trefoil, alfalfa and white clover) and grasses (meadow brome, timothy, tall fescue, Kentucky bluegrass, meadow fescue and orchard grass) under cutting and grazing management (Bélanger et al., 2018).

Beef cattle. In summer, when grasses slow down, birdsfoot trefoil better sustains gains. In Nappan, NS, over five years, complex pastures including trefoil produced ~40 % more gain/ha than comparable systems built on alfalfa (Bélanger et al., 2018). In Missouri, the introduction of birdsfoot trefoil to nitrogen-fertilized grasslands also increased daily gains.

Figure 7 Weight gain per hectare obtained with eight complex mixtures, consisting of one legume and three or four grasses, grazed at Nappan (N.S.). Average of five years following seeding (2011-2015). FLp: Timothy, FEp: Fescue, Pp: Kentucky bluegrass, Fe: Tall fescue, Ar: Reed canarygrass, Bp: Meadow bromegrass, Dp: Orchardgrass (Bélanger et al., 2018).

Grazing safety. Unlike alfalfa and clover, birdsfoot trefoil does not cause bloat thanks to its tannins (McMahon et al., 2000), which limit foam and viscous substances in the rumen. The result: a wider grazing window and less risk management.

Parasitism. Tannins also have anti-parasitic effects: the higher the concentration (g/kg DM), the greater the reduction in gastrointestinal parasite egg excretion. This is not a "treatment", but a useful boost if grazing management (rotation, heights, loading) is consistent.

5) Environmental effects

Beyond animal performance, trefoil tannins modulate nitrogen fate. A meta-analysis of 58 studies reports ~16 % lower ruminal ammonia and ~11 % lower urinary nitrogen when tannins are present, with a greater proportion of nitrogen excreted in feces (Herremans et al., 2020). This is advantageous: urinary nitrogen rapidly volatilizes into NH₃ or transforms into N₂O (a potent GHG), while fecal nitrogen is released more gradually, limiting losses and pollution.

6) Location and management

Before sowing. The year before planting :
- Clean up problem perennials.
- Correct pH if necessary (target ≥ 6.0).

Sowing and first year.
- Well-prepared seedbed, soil ≥ 10 °C.
- Depth 1-2 cm, excellent soil-seed contact.
- Low-competition companion grasses (e.g. timothy, bluegrass).
- Specific inoculation Rhizobium for a good fixation of N.
- First year :
- 1st cut when grasses reach ~20-25 cm.
- Wait until the birdsfoot trefoil is in full bloom before harvesting (encourages rooting).
- Avoid mowing after August 15 if it has not flowered.

Subsequent years (mowing).
- 1st cut at the start of flowering, followed by mid-flowering cuts about 6 weeks apart.
- Leave a 7-10 cm thatch to support regrowth.
- Allow to go to seed every 2-3 years to prolong longevity.
- Caution with autumn cuttings: lower root reserves than alfalfa.

Grazing.
- Take advantage of the absence of bloating for smoother rotations.
- Enter at a sufficient height (to optimize ingestion), exit high enough to preserve growth points.
- In summer, birdsfoot trefoil stabilizes intake when grasses slow down.

Fertility and soil.
- As a legume, birdsfoot trefoil fixes nitrogen: reduce mineral inputs according to objectives.
- Monitor pH, P and K; ensure favourable structure (drainage, absence of compaction). Drainage/decompaction may be necessary in hydromorphic soils.

7) Cultivars available

Three main types:
- Prostrate (Empire, Fergus, Leo): low-growing, very well adapted to prolonged grazing.
- Half-addressed (Dawn, Norcen, Mackinaw): compromise between mowing and grazing, good disease tolerance.
- Dressed (Viking, Maitland): more productive in hay/ silage, less persistent in pasture.
The choice depends on the dominant use (mowing vs. grazing), the soil and the climatic risks (frost, icy spells).

8) Key points to remember

- Floors : clear advantage in imperfect drainage or slightly acidic pH, if surface ice is avoided.
- Yield alfalfa: sometimes inferior to alfalfa in pure multi-cut cultivation, but very competitive - even superior - in mixtures with bromegrass or timothy under frequent cutting.
- Quality Slower decline with ripening; wider harvest window.
- Silage more stable fermentation, less ammonia and undesirable acids; watch out for very high tannin levels.
- Animal no bloat; good dairy and growth performance, especially in summer.
- Pests Potato leafhopper: little attacked by potato leafhoppers.
- Environment improved nitrogen efficiency and reduced urinary losses.
- Management : more delicate implantation (slow initial growth), less aggressive companions, cutting heights and intervals to be respected.

Conclusion

Bird's-foot trefoil is a strategic option for diversifying meadows and pastures, particularly on poorly drained soils where alfalfa is less able to express its potential. Its unique combination of stable yields in wet conditions, grazing safety (no bloat), and the beneficial effects of tannins on nitrogen efficiency and silage fermentation make it a lever for technical and environmental resilience. Admittedly, it requires more care to establish, and gross yields can sometimes lag behind alfalfa in pure multi-crop cultivation. But its benefits for animal health, risk management and the environment make it an ideal ally for high-performance, sustainable forage systems.

References cited:

Bélanger, G., Tremblay, G., Papadopoulos, Y., Duynisveld, J., Lajeunesse, J., Lafrenière, C., and Fillmore, S. 2018. Forage mixtures adapted for grazing. Conference presented as part of the "Colloque sur les plates fourragères". https://www.agrireseau.net/documents/Document_97126.pdf

Burton, S., Clarke, A., & Carroll, K. 2016. Forage Fact #105: Why is Birdsfoot Trefoil Called "The Pasture Legume"? Peace River Forage Association of British Columbia. https://www.agrireseau.net/documents/Document_97126.pdf

Darby, H., Ziegler, S., Krezinski, I., Malone, R., & Ruhl, L. (2019). Legume Variety Trial. Northwest Crops & Soils Program, UVM Extension, University of Vermont. https://scholarworks.uvm.edu/nwcsp/345.

Government of Manitoba (2021). Birdsfoot trefoil seed production. Manitoba Agriculture. https://www.gov.mb.ca/agriculture/crops/crop-management/forages/birdsfoot-trefoil-seed-production.html

Herremans, S., Vanwindekens, F., Decruyenaere, V., Beckers, Y., & Froidmont, E. (2020). Effect of dietary tannins on milk yield and composition, nitrogen partitioning and nitrogen use efficiency of lactating dairy cows: A meta-analysis. Journal of Animal Physiology and Animal Nutrition, 104(4), 1209-1218.

Jayanegara, A. and Palupi, E. 2010. Condensed Tannin Effects on Nitrogen Digestion in Ruminants: A Meta-analysis from in Vitro and in Vivo Studies. Media Peternakan 33(3): 176-181 https://www.researchgate.net/publication/50589992_Condensed_Tannin_Effects_on_Nitrogen_Digestion_in_Ruminants_A_Meta-analysis_from_in_Vitro_and_in_Vivo_Studies

Johansen, M., Lund, P. and Weisbjerg, M.R. 2018. Feed intake and milk production in dairy cows fed different grass and legume species: a meta-analysis. Animal 12(1): 66-75.

McMahon, L. R., McAllister, T. A., Berg, B. P., Majak, W., Acharya, S. N., Popp, J. D., Coulman, B. E., Wang, Y., & Cheng, K.-J. (2000). A review of the effects of forage condensed tannins on ruminal fermentation and bloat in grazing cattle. Canadian Journal of Plant Science, 80(3), 469-485.

Null, D.E., and Wheaton H.M. 1993. Birdfoot Trefoil. University of Missouri Extension.

Penn State Extension. 2013. Harvest Management of Birdsfoot Trefoil. https://extension.psu.edu/harvest-management-of-birdsfoot-trefoil

Piluzza, G., Sulas, L., & Bullitta, S. (2013). Tannins in forage plants and their role in animal husbandry and environmental sustainability: A review. Grass and Forage Science, 69(1), 32-48.

Undersander, D., Greub, L., Leep, R., Beuselinck, P., Wedberg, J., Smith, D., Kelling, K., Doll, J., Cosgrove, D., Grau, C., Peterson, S., Wipfli, M., and English J. (1993). Birdsfoot trefoil for grazing and harvested forage. North Central Regional Extension 474. https://cropsandsoils.extension.wisc.edu/files/2022/11/NCR474-Birdsfoot-Trefoil-for-Grazing.pdf