Building Resilient Grassland for Grazing Dairy Systems

Dry conditions in recent seasons have highlighted the importance of productive, resilient grassland in grazing dairy systems. Understanding what is happening in your swards and making informed management decisions can help protect forage supply, milk production and nitrogen efficiency.

Resilience in grazing systems starts with understanding the true performance of your grassland. Early spring growth can look promising, but visual appearance does not always reflect productivity or forage quality.

Grass leys naturally change over time. In the first year after establishment, around 80 percent of the sown species may be present in the sward. By year five this can fall to about 50 percent, and by year ten productive species may represent only a small proportion of the sward.

This decline is often linked to soil pH and fertility, overgrazing, tight cutting, poaching, drainage limitations and the use of less persistent varieties.

Measuring grassland performance

Understanding how much forage each field produces is the first step in identifying underperforming swards. Recording trailer loads or monitoring grazing performance can provide a useful starting point.

Digestibility and milk from forage

Digestibility, measured as D value, is closely linked to metabolisable energy supply. Each one-unit increase in D value raises metabolisable energy by approximately 0.16 MJ per kilogram of dry matter. Producing one litre of milk requires around 5.4 MJ of metabolisable energy.

Modern perennial ryegrass typically delivers D values in the mid to high seventies, while weed grasses often sit in the low sixties or below.

Improving nitrogen use efficiency

Nitrogen response varies significantly between species. Modern perennial ryegrass provides the strongest response to applied nitrogen.

Clover can fix around 150 kilograms of nitrogen per hectare annually when well established, helping reduce reliance on fertiliser inputs.

Matching species to soil and system

Most reseeds combine diploid and tetraploid perennial ryegrass to balance persistence, utilisation and seasonal growth. Festuloliums and clovers can also contribute to resilience depending on soil type and system requirements.

The role of multi-species swards

Multi-species swards can support forage production during dry periods, but they require appropriate grazing management and careful species selection.

Reseeding for long-term resilience

Reseeding around 10 to 15 percent of the grazing platform each year helps maintain productivity, forage quality and nitrogen efficiency.