Value from grazing crops
Grazing crops can:
- fill the autumn–winter feed gap and reduce reliance on supplementary feeding of livestock
- allow grazing of annual pastures to be deferred
- reduce the risks from frost and disease by retarding development of early sown crops
A crop has an upright nature and substantial inter-row space prior to canopy closure (Figure 1). Hence, a crop with a low biomass will have much higher accessibility for grazing animals compared to pasture with a similar biomass. As a result, animals grazing crops early in the growing season are likely to achieve superior growth rates compared to those grazing pastures.
Grazing and grain yield potential
Grain yield is highly correlated with crop biomass at harvest (Figure 2). If grainyield is key to your business, manage grazing to allow sufficient biomass to be grown by harvest.
This work indicates that simulated, early, hard grazing (during tillering, leaving plants at 0–5 centimetres high) gives sufficient time for plants generate a good total crop biomass and yield at harvest.
Late light grazing (during early jointing, leaving plants 10–15 centimetres high) will leave good residual biomass post grazing, and can cope with less recovery time, still achieving good crop biomass/yield at harvest.
Note that any grazing that removes the developing head will dramatically reduce yield. Cereal and canola crops can be grazed before stem elongation without affecting yield.
The key to grazing a cereal crop is to leave more biomass behind as the time for recovery reduces. An easy way to do this is to keep an eye on the position of the developing head. Once stem elongation has commenced, as a rule, make sure you leave more than twice the length of stem above the head as the length below.
Steps for good management are:
- Control weeds to achieve best yield results from grazed crops.
- Use crops and varieties that have good early growth rates and suit the area – oats and barley provide good early growth.
- Sow as early as possible with added nitrogen fertiliser (test for phosphorus requirement).
- Comply with chemical withholding periods for any crop treatments applied prior to grazing.
- Start grazing once the crop is anchored in the soil – use the twist and pull test to confirm anchoring.
- Graze at an appropriately high stocking rate to ensure even grazing. You may need to use strip grazing fencing.
- Remove stock before all leaves are removed – leaving some leaf will improve recovery.
- To minimise grain yield loss, do not graze once stem elongation starts in cereals (growth stage 30), or after bud formation in canola.
Graze crops with animals that have been
- Vaccinate against pulpy kidney before introduction
- Ensure gut fill prior to introduction, to prevent too rapid a change in diet
- Provide plenty of roughage to balance crops low in fibre
- Provide salt and calcium (and magnesium when grazing wheat) as supplements to sheep before and during grazing cereals to minimise hypocalcaemia and grass tetany.
- Monitor the animals and manage them to achieve targets and care for their welfare.