The first grazing of perennial ryegrass should be delayed until seedlings are firmly established and feed-on-offer has reached about 1800 kg DM/ha to avoid stock pulling plants out of the ground.
Use a heavy stocking rate for a short period to promote the development of new tillers and graze down to ~1200 kg DM/ha. Remove dry residues from established stands of perennial ryegrass during autumn to encourage new tillers.
But do not graze too hard during this period – rotationally graze if possible to keep feed-on-offer (FOO) >1200 kg DM/ha. In winter, continue rotational grazing and maintain FOO between 1200 and 2000 kg DM/ha. Most tillering is initiated during autumn and winter and the yearly production is largely reliant on management during this period.
In spring, maintain between 1600 and 3000 kg DM/ha while continuing to rotate stock. To increase plant density, reduce the stocking rate to enable a more plants to set seed. Aim to have between 2000 and 3000 kg DM/ha at the end of spring to protect the soil surface and provide feed for stock during summer.
In summer do not graze hard or allow FOO to fall below 1500 kg DM/ha. Do not set-stock perennial ryegrass stands affected by moisture or heat stress otherwise plant death will occur. Pastures should be rested in areas with mean summer temperatures >30°C.
An alternative management approach is to allow plants to develop three leaves per tiller, graze intensively for a short period and then move stock on. Preventing the plant going beyond the three-leaf stage maximises pasture production and quality.
N and P levels can influence perennial ryegrass productivity and persistence significantly. Ideally N should be provided via a companion legume, however autumn and winter growth can be improved with fertiliser N in autumn (25 to 50 kg N/ha). Maintain soil phosphorus levels around a Cowell P of 30 ppm.
In a pasture mix with clovers, perennial ryegrass makes good quality hay or silage. The best time to cut hay is in the early flowering stage, as after this the nutritive value quickly declines.
Companion species:
It is compatible with most pasture legumes including subterranean clover, serradella, lucerne and perennial lotus. It is compatible with other temperate perennial grasses such as tall fescue, phalaris and cocksfoot, however the companion species need to be sown in separate rows or the more vigorous perennial ryegrass seedlings will dominate the sward.
Cultivars:
There are many cultivars of perennial ryegrass available in Australia. These can be grouped according to their maturity and number of chromosomes – very early maturing diploids, early maturing diploids, mid-late season diploids and late season tetraploids.
The mid- to late-season diploids and tetraploids are suited to regions such as south-west Victoria with fertile soils, high rainfall, long growing seasons and mild summers, so are less suited to WA.
Most (~70%) perennial ryegrass seed sold in Australia contains endophyte, but some varieties are now available with ‘novel’ endophyte or are free of endophyte. The ‘wild’ endophyte produces three main chemicals: peramine, lolitrem B (causes ryegrass staggers) and ergovaline (toxin that can reduce animal performance). The novel endophyte AR1, produces peramine to provide some insect resistance but produces no ergovaline or lolitrem B.
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