3.06 - Grazing management methods
Plant characteristics and pasture height based methods to start and stop grazing a paddock in a planned grazing sequence. Best practice tactical management of pastures may require slight variation of the limits to achieve seasonal objectives, for example, encourage desirable species and discourage undesirable species.
Process 1 – To start grazing
1. Based on characteristics of major desirable species –for maximum productivity
- Perennial ryegrass – graze at the 2.5–3-leaf growth stage
- Annual ryegrass – graze at the 2.5–3-leaf growth stage
- Phalaris – graze at the 4–5-leaf stage of regrowth
- Cocksfoot – graze at the 4–5-leaf stage of regrowth
- Kikuyu – graze at 4.5 new leaves since previous grazing
- Prairie (brome) grass – graze at 4 new leaves since previous grazing
In mixed swards, use the limit for the species that you want to encourage to be more productive.
2. Based on pasture biomass (or height)
Use when characteristic limits are not defined or inappropriate for the species present in the pasture
- Minimum mass of 1,500kg green DM/ha (5–6cm) for a moderately dense pasture
- Maximum mass of 3,000kg green DM/ha (14cm) for a moderately dense pasture
- Tall fescue – provide adequate rest and regrowth to around 2,000kg green DM/ha (8–10cm)
These pasture availability methods are indicative only. Very dense, closely grazed pastures will have a higher (up to +25%) kg green DM/ha at the same height. Conversely, more open, lightly grazed pastures have a lower kg green DM/ha at the same height. The differences due to density are greater at pasture heights above 6cm.
In legumes the criterion measured is the percentage leaf area index (LAI) to capture the energy from sunlight or height in some species.
- Maximum limits:
- All legumes – 95% LAI
- White clover – height 20–25cm
- Red clover – height 25–50cm
- Lucerne just prior to the emergence of the new growth buds on the crown
4. Native based pastures
Graze more heavily in spring to utilise the green feed and to promote flowering of sub clover and control of annual grass. Avoid overgrazing in dry summers and in wet years manage rank growth in autumn.
Note that pasture intake of cattle will start to be depressed when grazing starts at pasture heights of less than 9cm (around 2,000kg green DM/ha). Achieving maximum intake of energy dense pasture per animal only occurs in that 9–12cm window (2,000–2,500kg green DM/ha). This only has impact if maximum growth rate of finishing animals is required to be above 1.5kg/day.
Process 2 – To stop grazing
- To maximise pasture regrowth rates – minimum limit of 1,000kg and maximum limit of 1,500kg green DM/ha (around 3–5cm height) for all introduced species other than phalaris. Aim towards the minimum of 1,000kg green DM/ha in spring for most rapid pasture growth and to maintain control of species such as ryegrass, fescue and kikuyu.
- For phalaris based pastures, the minimum limit is closer to 1,500kg green DM/ha.
- Across much of southern Australia, where the growing season is 5–8 months following the autumn break, the maximum limits for residual (post-graze) pasture mass will be lower than 1,000kg DM/ha in autumn and early winter; however, the sooner they are above 1,000 kg DM/ha the more pasture will be grown. Give consideration to feeding stock in containment area or several sacrifice paddocks to increase pasture on offer across the whole farm.
- To provide protection of a fragile resource base a minimum pasture mass of 800kg total DM/ha and minimum of 70% groundcover (100% if slope is steep) is recommended.
In higher rainfall areas:
- recognise the special needs of desirable native grasses and use grazing systems that will encourage and maintain their productivity
- graze to maintain the legume content below 20% clover
- rest at critical times for re-seeding, depending on the growth characteristics of the desirable native species and predicted rainfall pattern;
Subdivide paddocks according to grassland type and monitor the available feed to ensure that overgrazing does not occur at critical times of the year