Milk production systems research

Why is this research important?

Improving the efficiency of future dairy production systems is necessary to meet increased food demand while competing for inputs, adapting to climate change, and delivering ecosystem services. Future grazing systems can play a major role in the supply of healthier foods within systems with a reduced reliance on fossil fuels and chemical inputs, while also delivering environmental, biodiversity, and animal welfare benefits. Can we design lower-input systems that deliver efficient levels of output and better environmental outcomes? Monocultures of perennial ryegrass (PRG) have traditionally dominated grazing swards. The highly seasonal growth pattern of PRG, particularly in the context of increasingly variable weather conditions, and increasing pressure to reduce both chemical fertiliser and herbicide use have brought this practice into question. A full farm systems evaluation of PRG only swards supported by high levels of chemical N application and alternative low chemical N input systems across a range of soil types merits further evaluation.

What the research tells us

The primary objective of the milk production systems research programme is to quantify the long-term impact of low chemical N input systems and improved animal nutrition strategies on both pasture and animal performance, environmental footprint and economic performance of Irish pasture-based dairy systems. Recent studies have demonstrated that the pasture DM yield of swards that incorporate additional plant species are comparable with PRG only swards, require fewer chemical fertiliser applications and support greater animal performance at grazing. The evaluation of the initial establishment and long-term performance of PRG plus clover swards under diverse soil types, varying levels of chemical N fertiliser application and different grazing management practices is critical to reduce the dependence of Irish grazing dairy systems on chemical fertilisers.

Clonakilty Farm – Grass clover study

Systems research studies in Clonakilty have focused on strategies to reduce the environmental impact of dairy production by reducing fertiliser use and incorporating white clover into PRG swards. Several alternative fertiliser application rates combined with PRG-white clover swards have been investigated. The treatments on the current study are comparing PRG-clover swards that receive either 150 or 75 kg nitrogen/ha, compared with PRG-only swards that receive either 225 or 150 kg nitrogen/ha. The results to date from the current study indicate that animal performance can be maintained or increased using low levels of nitrogen fertiliser when white clover is included in the sward. When nitrogen fertiliser is reduced, however, absence of white clover in the sward (i.e. PRG-only sward receiving 150 kg N/ha) or if there is inadequate white clover in the sward (i.e., a PRG-clover sward with <XX% clover receiving 75 kg N/ha), herbage production is reduced significantly.

Solohead farm – Lowering the carbon and ammonia footprints of milk production

At Solohead we have lowered the carbon footprint of milk production by up to 30% and ammonia emissions by 40%. Most of these emissions reductions were due to N fixed by clover to replace fertilizer N. For the last five years (2019 to 2023) we have been running a clover-based system of milk production with zero fertilizer N input. There has been no reduction in pasture production and milk output compared with a high input control treatment receiving an annual average of 265 kg/ha of fertilizer N. This high rate of fertilizer N input is no longer allowed and fertilizer N use is being increasingly restricted on farms. The zero-N clover-based system at Solohead is comparatively profitable compared to high fertilizer input PRG only swards, particularly with the very high costs of fertilizer N in recent years (2022 and 2023). The challenge in the future is to facilitate wider adoption of the zero-N system on farms.

Curtins Farm - The Multi-milk research project

In addition to PRG and white clover, recent international research projects have identified several additional plant species with high forage production potential that may improve animal performance and reduce the environmental impacts of grazing dairy systems. Among these diverse plant species, chicory and plantain are deep-rooting broad-leafed forage forbs, and are valuable complementary forage species with high productivity and feed value. In extensive low input European grassland studies, increased plant diversity has also been linked to increased N use efficiency, elevated soil carbon sequestration, enhanced food product characteristics and increased resistance to climate change and weed invasion. To date, however, only limited data is available on the performance of intensively managed diverse pastures under grazing, and there has been relatively low adoption of more diverse mixtures. The objective of this cross-disciplinary project is to evaluate the potential of PRG-clover and multispecies swards to support high levels of productivity with reduced requirements for chemical N application in pursuit of grazing systems with less impact on the environment.

Outputs

Contacts

Solohead Farm: Evaluation of Low Nitrogen Dairy production systems: James Humphreys (james.humphreys@teagasc.ie)
Clonakilty Farm: Evaluation of Nitrogen application for clover-based systems: Brian McCarthy (brian.mccarthy@teagasc.ie)
Curtins Farm: Multimilk: impacts of animal and pasture species diversity on the performance of spring calving dairy systems: Brendan Horan (brendan.horan@teagasc.ie)