Annual pasture quality and quantity

Page last updated: Thursday, 11 October 2018 - 2:45pm

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Key FOO targets

Managing pastures to key FOO targets can result in improved production of grazing systems in mediterranean environments which are characterised by slow winter growth, peak spring growth and dry summers. These targets vary according to what production response is required.

Autumn

Figure 1 500kg DM/ha FOO in autumn. This grassy pasture is short and there are areas of bare ground

This is the minimum FOO that should be present before sheep are allowed to graze a paddock that has been deferred after the break. Overgrazing too soon after the break can lead to significant loss of plant density. The objective is to maximise FOO going into winter so that pasture growth is not reduced due to a decreased leaf area. A FOO of around 500kg DM/ha will maintain the condition of medium-framed single-bearing Merino ewes from day 100 of pregnancy.

Winter

Figure 2 800kg DM/ha FOO in early winter. This pasture looks a lot more than 800kg DM/ha, but due to the higher water content in young plants, the actual FOO is lower than it might appear. In spring, a pasture like this might measure closer to 2000kg DM/ha. Care must be taken not to overestimate autumn/winter FOO

Around 800kg DM/ha is the minimum FOO required from day 100 of pregnancy to ensure a gradual increase in condition of single-bearing ewes. Twin-bearing medium-framed Merino ewes need around 900kg DM/ha FOO. If maintained through winter, this FOO will maximise branching in clovers, resulting in increased clover content in spring. It will also reduce insect populations such as red-legged earth mite (RLEM) and lucerne flea.

Spring

Figure 3 1700kg DM/ha FOO in spring. This grassy pasture is short, dense and was heavily grazed through winter. The density due to winter grazing, and lower water content compared to autumn pastures, means there is more FOO than meets the eye

This FOO will maintain condition of adult medium-frame Merino ewes during lambing and lactation. If maintained through spring, it will result in increased clover and reduced grass content in the pasture. However, clover seed-set will be reduced unless the grazing pressure is released at 20% flowering. Redlegged earth mite and lucerne flea insect populations will be reduced in the current and following seasons if FOO is maintained at this amount through spring.

2000 FOO in Spring, if tightly grazing is only 2 to 3 cm high.
Figure 4 2000kg DM/ha FOO in spring. This pasture was heavily grazed through winter and is only 2-3 centimetres high

A minimum of 2000kg DM/ha FOO is required for near-maximum feed intake of grazing sheep. That is, sheep will grow at their near-maximum rate if provided with 2000kg DM/ha FOO and will not grow significantly faster if given access to more feed.

Don’t forget: FOO in autumn looks very different to FOO in spring. A general rule is that pasture height in autumn is double that in spring for the same FOO level.

Contact information

Danny Roberts
+61 (0)8 9892 8535
Perry Dolling
+61 (0)8 9821 3261