Agronomic performance of ten perennial ryegrass varieties on commercial grassland farms

C Hearn,M.B Lynch,D.P Berry,A Geoghegan,M O'Donovan,M Egan,M O'Leary

doi:10.1017/s0021859621000927

Abstract

AbstractLittle information is available on the phenotypic performance of perennial ryegrass varieties when exposed to grazing conditions on commercial grassland farms. Grass varieties are classically evaluated in mechanically defoliated plot systems which, although designed to mimic grazing conditions, do not fully capture the range of stresses or interactions that a sward is subjected to under commercial settings or over any period longer than 4 years. The evolution of technology in the form of PastureBase Ireland has led to agronomic data of individual paddocks being made available for analysis over multiple years. Data used in the current study consisted of dry matter (DM) production and ground score data across a 7-year period from ten perennial ryegrass varieties grown as monocultures in 559 paddocks on 98 commercial farms. The results demonstrated how perennial ryegrass variety is associated with a range of agronomic performance traits on commercial farms; including total and seasonal DM production, grazing DM production and number of grazing events. Varieties with the highest total DM production also had the highest spring and mid-season DM production; autumn DM production was associated with the interaction between variety and year. The highest producing variety in the study, AberGain, produced 1342 kg DM/ha/year more than the mean of all other varieties. Variety differences manifested themselves as swards aged, with some varieties increasing in total DM production while others reduced in total DM production. The current work provides a basis for the consideration of on-farm variety assessment in the composition of future variety evaluation protocols.

Highlights

Improved grass growth and utilization is a key component of maintaining the economic and environmental sustainability of ruminant production systems in temperate environments (Peyraud et al, 2010; Conant et al, 2017; Neal and Roche, 2020). Chapman et al (2008) outlined how farm profitability is directly related to the quantity of grass grown and utilized through grazing on-farm
A review of New Zealand (NZ) grass breeding stated that any further increase in fertilizer inputs above those already used by grassland farmers will not increase PRG dry matter (DM) production (Parsons et al, 2011)
Drought conditions prevailed across Ireland for approximately 12–16 weeks in the summer of 2018 causing daily grass growth rates to fall below 30 kg DM/ha/day when the 7-year average was 60 kg DM/ha/day for the same 4 week period (Fig. 1)

Summary

Introduction

Improved grass growth and utilization is a key component of maintaining the economic and environmental sustainability of ruminant production systems in temperate environments (Peyraud et al, 2010; Conant et al, 2017; Neal and Roche, 2020). Chapman et al (2008) outlined how farm profitability is directly related to the quantity of grass grown and utilized through grazing on-farm. Perennial ryegrass (Lolium perenne L., PRG) is considered the most important temperate forage species used in pasture production (Easton et al, 2001; McEvoy et al, 2011a). This is due to its high nutritive value and relatively low cost compared to other feed sources for ruminants (Finneran et al, 2010). Grass growth and utilization can be improved through a combination of reseeding of poor-performing pastures with higher-performing grass varieties as well as better aligning grass growth and feed requirement over the grazing season (Shalloo et al, 2011). The use of improved grass varieties, with increased DM production and nitrogen (N) use efficiency, will be required in the future to increase the efficiency of pasture production systems (O’Donovan et al, 2011; Cameron et al, 2013)

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