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Curtins Research Farm, Fermoy, Co. Cork

MultiMilk: Evaluation of Low Nitrogen Dairy Systems 2021-2025

Update by Alann Jezequel 

The MultiMilk project at Curtins Farm Teagasc Moorepark is comparing the effect of three different swards under different levels of fertiliser nitrogen. A perennial ryegrass only sward (PRG) with 250 kg Nitrogen (N) applied per hectare (ha) is being compared with two low N sward options in terms of pasture and animal performance and environmental and milk product quality impacts. The two low N systems which will receive 125 kg N/ha each yr are a classical perennial ryegrass + white clover sward and a multispecies sward containing 8 species (3 grasses, 3 clovers plus plantain and chicory).  Each sward type has its own unique herd of high EBI dairy cattle which exclusively graze that sward over the entire grazing season. The trial commenced in January 2021 and the preliminary results from the first grazing season are presented below. There was no significant differences in pre grazing herbage mass (1,653 kg DM/ha), post grazing residual grazing height (4.1 cm) or total pasture production (12.4 t DM/ha) between treatments during 2021 despite a large differential in chemical N application. Sward DM content was significantly lower for MSS (15.0%) compared to both PRG and PRGWC swards (16.4%). The contribution of clover and herbs to the total sward biomass varied across the season. Clover content was similar for both PRGWC and MSS swards and ranged from 1% during rotation 1 to 20-25% in rotation 7 and 8 during autumnThe evolution followed the same trend for PRGWC and MSS, at the end of the year the clover content was around 20% for both swards. Herb contents in the MSS sward were stable over the season at approximately 20% of the total sward biomass. Total lactation milk and fat plus protein yield was on average 5,586 and 517 kg per cow, respectively and was similar for all 3 sward types. Similarly, the profile of daily fat plus protein production also followed the same trend over the lactation for the three sward groups.

The project will continue for 4 additional years. Discussion groups are welcome to arrange to visit the study during the year with arrangements made via their local Teagasc advisor.  The contribution of Irish Dairy Research levy funding to the project is gratefully acknowledged.