Signpost Series: MultiMilk Project

Why It Matters

Diversified swards deliver comparable yields with less fertilizer, higher milk output, and lower methane intensity—key levers for sustainable, profitable dairy farming.

Key Takeaways

• Multi-species swards match grass-only dry matter yields with lower nitrogen
• Milk production rises as sward diversity increases, despite similar feed inputs
• Multi-species pastures cut methane intensity per kilogram of milk solids
• Clover and herb components remain below target levels, showing establishment variability
• Long-term field data provide farmers with evidence for sustainable, profitable grazing systems

Summary

The Signpost webinar introduced the MultiMilk Project, a six‑year farm‑systems study examining how sward species diversity—grass, clover and herbs—affects pasture productivity, animal performance, and environmental outcomes in Irish grazing dairy farms. Researchers established three treatment plots in 2021: a high‑nitrogen perennial ryegrass (PRG) sward, a PRG‑white clover mix with half the nitrogen, and a multi‑species sward (grasses, clovers, herbs) also on reduced nitrogen.

Over the first five years, dry‑matter yields were comparable across treatments (13.3 t ha⁻¹ for PRG, 12.5 t ha⁻¹ for grass‑clover, 13.2 t ha⁻¹ for multi‑species), demonstrating that lower fertilizer inputs do not sacrifice biomass. Milk output increased stepwise from grass‑only to grass‑clover to multi‑species swards, while milk protein remained stable and fat modestly declined. Animal intake and energy consumption were higher on the more diverse swards, translating into greater milk‑solid yields per cow.

Key observations included modest clover establishment (15‑16 % vs. the 25 % target) and variable herb persistence—plantain held ~10 % but chicory declined sharply after two years. Chemical analyses showed minimal differences in crude protein and fiber, with only a slight rise in ash for the multi‑species mix. Notably, methane emissions per cow were similar across grass‑only and multi‑species plots, but methane per kilogram of milk solids fell significantly on the diverse sward, indicating improved greenhouse‑gas efficiency.

The findings suggest that adopting multi‑species pastures can maintain or boost dairy productivity while cutting nitrogen fertilizer costs and reducing the carbon intensity of milk. For policymakers and farm advisers, the long‑term dataset offers concrete evidence to support sector‑wide moves toward biodiversity‑rich, climate‑smart grazing systems.

Original Description

On this episode of the Signpost Series which took place on Friday, 17 April, host Cian Condon, KT Outreach & Innovation Specialist, Teagasc was joined by Dr. Brendan Horan, Teagasc to discuss the MultiMilk project: impacts of sward species diversity on the performance of spring calving grazing dairy systems. A questions and answers session took place at the end of the presentation, which was facilitated by Oisin Coakley, Catchment Coordinator, Teagasc.