As part of the management of intensive grazing, the focus on simple and productive forage systems has led to a limited range of plants being used in grazing swards and supported by higher levels of chemical fertilisers and supplemental feeds. With increasing pressures on all agricultural systems to reduce environmental impacts while increasing productivity, there is a growing awareness of the potential contribution of plant and animal species diversity to improve the performance of grazing systems through increased animal lifetime performance efficiency and reduced chemical fertiliser, feed and herbicide use requirements within our changing climatic conditions.
The potential of legumes and herbs
Grass-legume mixtures such as ryegrass-clover swards have been reported to reduce chemical N requirements, increase sward quality and animal intake and performance. More recently, a number of additional dicotyledonous plant species with high forage productivity potential have also been identified. Among these diverse plants, Chicory (Cichorium intybus L.) and Plantain (Plantago lanceolate L.) are deep-rooting broad-leafed forage forbs, which have high productivity and feed value. Recent studies suggest that the yield and quality of multi-species swards containing perennial ryegrass (PRG), white clover (WC), alternative legumes such as red clover and forage herbs such as chicory and plantain are comparable with PRG only and PRG-WC only grazing swards, with lower fertiliser N fertiliser and herbicide inputs required. In extensive low input studies in Ireland, the United Kingdom, Europe and Australasia, increased plant diversity has also been linked to increased N use efficiency, elevated soil carbon sequestration, enhanced food product character, enhanced biodiversity and increased resistance to climate change and weed invasion. To date however, there is limited data 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 WC and MSS swards to support high productivity with a reduced requirement for chemical N application in pursuance of more environmentally friendly regenerative grazing systems for Ireland. The new project on Curtins farm will run for 5 years and compare the performance of diverse animal genotypes (Holstein-Friesian and Jersey Holstein-Friesian crossbreds) and grazing swards (PRG, PRG-White clover (WC) and a multispecies sward (MSS)). The complete farm area have been reseeded in spring 2020 and 2021.
Figure 1: organization of the study
Table 1: Composition of the three swards sown (kg/ha)
Each farmlet is managed with a stocking rate of 2.7 cows/ha and in line with the objective of reducing the chemical fertiliser, the PRG will receive 250 kgN/ha/yr while the PRG-WC and the MSS will receive 125-150 kg N/ha/yr (Figure 1).
Sward measurements (Each grazing event)
- Pre-grazing herbage mass, sward density
- Botanical composition
- Total net herbage accumulation and utilisation
- Chemical analysis (OMD, NDF, ADF, CP)
- Silage yields and quality
Animal measurements (Seasonal/Annual)
- Milk yield daily and constituent weekly
- Body weight and BCS biweekly
- Incidence of ill-health/ lameness/ mastitis
- Fertility performance
Environmental measurements (Seasonal/Annual)
- Soil fertility
- 0N plot to measure N mineralisation
- Nitrate concentrations in soil solution and groundwater
- N and P balances and use efficiency
- Green House Gas emissions modelling
Milk product character (Seasonal)
- Characterise the variability of milk fine composition
- Mineral, vitamin and amino acids
- Heat stability, colour, texture and sensory properties
- Impacts of systems on receipts and costs
- Net profit (€/ha)
MultiMilk Project Partners
The project is a collaborative initiative involving Teagasc colleagues from Crops Environment and Land Use Programme at Johnstown Castle (Dr. Karen Daly, Professor Owen Fenton, Dr. John Finn, Dr. Karl Richards and Dr. David Wall), Rural Economy Research Programme (Dr, Cathal Buckley) and Food Programme (Dr. Laura Mascaraque, Dr. Jonathan Megan and Dr. John Tobin) in addition to collaborating scientists from Irish (Dr. Caroline Brophy, TCD; Dr. Doris Laepple, NUIG; Dr. Tom O’Callaghan and Dr. Alan Kelly, UCC and Dr. Zoe McKay, UCD) and international (Dr. Nandita Basu, University of Waterloo, Canada) universities.
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