The Impact of Herbage Mass on Perennial Ryegrass Swards in Autumn on Autumn and over Winter Production and Characteristics

Caitlin Looney,Michael Egan,Astrid Wingler

doi:10.3390/agronomy11061140

Abstract

Accumulating herbage mass to facilitate the extension of the grazing season in autumn is commonly practised. The objective of the current study was to investigate the effect of accumulating varying target herbage masses (THM) in autumn and imposing different defoliation dates (DD), on herbage mass, sward quality and water-soluble carbohydrates in autumn and the subsequent spring. A 4 × 3 factorial split plot design was assigned with four THM (Low ≈ 500 kg·DM·ha−1, Medium ≈ 1500 kg·DM·ha−1, High ≈ 2000 kg·DM·ha−1 and Very high ≈ 3000 kg·DM·ha−1) and three DD (DD1—15 October, DD2—7 November and DD3—21 November), across two years. Measurements were carried out at each DD and in spring. Differences in sward quality were found between each THM on different DD. Sward quality reduced from DD2 to DD3 in the high THM (−13 g·kg−1 DM CP, p < 0.001). The very high THM had the lowest sward quality from DD1 (206 g·kg−1 DM CP, p < 0.001 and 787 g·kg−1 DM DMD, p < 0.05). This study has identified the defoliation date of THM in autumn as key to improving autumn management strategies for increased utilisation and sward quality.

Highlights

IntroductionTemperate oceanic climatic zones have the potential to support a competitive and sustainable pasture-based production system [1]
The objective of this study was to investigate the effect of accumulating herbage mass in autumn and imposing different defoliation dates in the final grazing rotation to determine the impact on herbage mass, sward quality and water soluble carbohydrates (WSC) in the stubble in autumn and the subsequent carryover to spring
The date on which swards are defoliated in autumn can have a significant impact on herbage available in spring, with a 24% reduction in swards defoliated in DD2 compared to DD1

Summary

Introduction

Temperate oceanic climatic zones have the potential to support a competitive and sustainable pasture-based production system [1]. Perennial ryegrass (Lolium perenne L.; PRG) is the central species in temperate pasture-based systems [2], as it can produce large quantities of high-quality herbage [3] and can persist under intensive grazing [4]. To improve environmental [5] and economic [6,7] sustainability within a pasture-based system, the production and utilisation of grazed grass must be maximised. Grazed grass has been identified as the cheapest feed source available within ruminant production systems [8], and as such, increasing the proportion of grazed grass in the diet of animals [9] is a key objective of pasture-based dairy production systems. The efficient utilisation of swards was defined as the proportion of green leaf tissue that is removed by grazing animals before entering the senescent state [10]

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