Abstract
A key goal of temperate pasture management is to optimise nutritive value and production. The influence of individual components such as irrigation, nitrogen (N) fertiliser, and grazing interval and intensity has been well researched, yet conjecture remains regarding practices that optimise pasture nutritive value, largely because interactions between inputs and grazing management have not been quantified. A 2-year, split-split-plot experiment was undertaken to investigate these interactions in a perennial ryegrass (Lolium perenne L.) dominant pasture at Elliott, Tasmania. Irrigation treatments (rainfed or irrigated) were main plots and defoliation intervals (leaf regrowth stage: 1-, 2- or 3-leaf) were subplots. Defoliation intensity (defoliation height: 30, 55 or 80 mm) and N fertiliser (0, 1.5 or 3.0 kg N/ha.day) were crossed within sub-subplots. Herbage samples were collected from each plot four times during the experiment and analysed for concentrations (% dry matter, DM) of neutral detergent fibre (NDF), acid detergent fibre (ADF) and crude protein (CP). Metabolisable energy (ME) concentration (MJ/kg DM) was estimated from these values. ME concentration decreased as defoliation height and interval increased for all time points except during winter. Crude protein concentration increased with increasing N fertiliser applications in the plots defoliated at the 1-leaf stage, but only as N applications increased from 1.5 to 3.0 kg N/ha.day for the plots defoliated at the 2- and 3-leaf stages. As N application rates increased from 0 to 1.5 kg N/ha.day, plots defoliated at the 3-leaf stage had greater increases in NDF concentration than plots defoliated at the 1-leaf stage, except during spring. As defoliation height and interval increased, ADF concentration increased in both spring and summer. Although defoliating at frequent intervals (1-leaf stage) and lower heights (30 mm) produced pasture of marginally higher nutritional value, these benefits are mitigated by the previously established, negative consequences of lower pasture yield and poor pasture persistence. Consequently, grazing management that maximises pasture productivity and persistence (i.e. defoliation between the 2- and 3-leaf regrowth stages to a height of 55 mm) should be applied to perennial ryegrass pastures irrespective of input management.
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Claims 7
Claim · model-written summary
Metabolisable energy concentration of perennial ryegrass decreased as defoliation height and interval increased, except in winter.
- Taxon
- perennial ryegrass
Lolium perennet0 - Treatment
- defoliation height and intervale1
- Outcome
- ME concentratione1
- Direction
- decreasede1
- Qualifier
- except during wintere1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“perennial ryegrass”
e1“ME concentration decreased as defoliation height and interval increased for all time points except during winter”
Claim · model-written summary
Crude protein concentration increased with N fertiliser in plots defoliated at the 1-leaf stage.
- Taxon
- perennial ryegrassLolium perennet0
- Treatment
- N fertilisere2
- Outcome
- Crude protein concentratione2
- Direction
- increasede2
- Qualifier
- in the plots defoliated at the 1-leaf stagee2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“perennial ryegrass”
e2“Crude protein concentration increased with increasing N fertiliser applications in the plots defoliated at the 1-leaf stage”
Claim · model-written summary
Crude protein concentration increased only as N applications rose from 1.5 to 3.0 kg N/ha.day in plots defoliated at the 2- and 3-leaf stages.
- Taxon
- perennial ryegrassLolium perennet0
- Treatment
- N applicationse3
- Outcome
- Crude protein concentratione2
- Direction
- increasede3
- Value
- 1.5 to 3.0 kg N/ha.daye3
- Qualifier
- for the plots defoliated at the 2- and 3-leaf stagese3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“perennial ryegrass”
e2“Crude protein concentration increased with increasing N fertiliser applications in the plots defoliated at the 1-leaf stage”
e3“but only as N applications increased from 1.5 to 3.0 kg N/ha.day for the plots defoliated at the 2- and 3-leaf stages”
Claim · model-written summary
As N application rose from 0 to 1.5 kg N/ha.day, plots defoliated at the 3-leaf stage had greater increases in NDF concentration than plots at the 1-leaf stage.
- Taxon
- perennial ryegrassLolium perennet0
- Treatment
- N application ratese4
- Outcome
- NDF concentratione4
- Direction
- greater increasese4
- Value
- 0 to 1.5 kg N/ha.daye4
- Qualifier
- except during springe4
- Comparator
- plots defoliated at the 1-leaf stagee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“perennial ryegrass”
e4“As N application rates increased from 0 to 1.5 kg N/ha.day, plots defoliated at the 3-leaf stage had greater increases in NDF concentration than plots defoliated at the 1-leaf stage, except during spring”
Claim · model-written summary
ADF concentration of perennial ryegrass increased as defoliation height and interval increased, in spring and summer.
- Taxon
- perennial ryegrassLolium perennet0
- Treatment
- defoliation height and intervale5
- Outcome
- ADF concentratione5
- Direction
- increasede5
- Qualifier
- in both spring and summere5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“perennial ryegrass”
e5“As defoliation height and interval increased, ADF concentration increased in both spring and summer”
Claim · model-written summary
Frequent defoliation intervals and lower heights produced pasture of marginally higher nutritional value.
- Taxon
- perennial ryegrassLolium perennet0
- Treatment
- frequent intervals (1-leaf stage) and lower heights (30 mm)e6
- Outcome
- nutritional valuee6
- Direction
- highere6
- Qualifier
- marginallye6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“perennial ryegrass”
e6“Although defoliating at frequent intervals (1-leaf stage) and lower heights (30 mm) produced pasture of marginally higher nutritional value”
Claim · model-written summary
Defoliation between the 2- and 3-leaf stages to 55 mm should be applied to perennial ryegrass pastures to maximise productivity and persistence.
- Taxon
- perennial ryegrassLolium perennee7
- Treatment
- defoliation between the 2- and 3-leaf regrowth stages to a height of 55 mme7
- Outcome
- grazing management that maximises pasture productivity and persistencee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“grazing management that maximises pasture productivity and persistence (i.e. defoliation between the 2- and 3-leaf regrowth stages to a height of 55 mm) should be applied to perennial ryegrass pastures irrespective of input management”
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