best practice management guide for south-eastern Australia - Grains ...

Grazing and fodder conservation
11. Grazing and fodder conservation
Paul Parker, NSW DPI
In dry seasons, or when spring conditions are poor, growers
have a number of options to recoup some or all of their
growing costs. Crops can be grazed, made into hay or
silage, or left for grain harvest.
The decision will depend on a number of factors,
including availability and class of stock, market demand and
price of fodder, price of grain, anticipated fodder or grain
yield, proximity to markets, and farm operational factors.
Computer software is available on the NSW DPI website
(www.dpi.nsw.gov.au) to assist with these decisions.
Soil conservation
Grazing or cutting canola usually results in a paddock with
minimal ground cover, increasing the risk of soil loss to
wind and water erosion. Maintaining some ground cover
is advisable otherwise more expensive soil conservation
measures such as ‘ridging’ will be needed if the dry
conditions develop into a drought.
Grazing failed
canola crops
Drought affected or failed canola crops can be grazed by
livestock. Experience gained in recent drought years has
reduced the risk of stock health problems and stock deaths.
Potential stock health risks
There are some risks to stock health and cases of sickness and
sudden death of livestock have occurred, usually when grazing
standing crops. However, the number of reported deaths has
been very low compared to the area of canola grazed.
Although initially believed to be nitrate poisoning, the
more common cause of death has been identified as
respiratory distress and failure caused by certain toxic
compounds. Other animal health problems recorded in stock
fed on a range of Brassica crops include:
n respiratory problems from a build-up of fluid on the lungs;
n photosensitisation causing sunburn of exposed skin;
n blindness which can be combined with ‘sudden
excitability’;
n digestive problems including rumen stasis (reduced rate
of flow through the rumen) and constipation;
n pulpy kidney; and
n bloat.
Nitrate poisoning can occur when hungry stock are first
introduced to canola, usually within the first 48 hours and
particularly where they have little or no gut fill. Crops that are
growing on fertile clover paddocks or have had moderate
to large amounts of nitrogen fertiliser applied before grazing
and then become stressed, pose more of a risk. Over time
stock can adapt to high levels of nitrates, but care is needed
to minimise potential problems.
Animal deaths due to other toxic compounds are less
predictable and could occur after the stock have been on
the canola for some days.
Minimising stock health risks
The following management strategies should minimise the
risk of health problems for livestock grazing a failed canola
crop:
n do not introduce hungry stock into the paddock;
n initially, restrict grazing to short periods or give stock
access to another paddock with different feed;
n provide supplementary feed such as hay or grain to dilute
the intake of canola;
n introduce a small number of stock and observe them
closely for a few days. If there are no problems, introduce
the rest of the mob ensuring they have at least partial
gut fill;
n monitor the mob regularly and remove them immediately
if any unusual behaviour is observed; and
n take special care and inspect the stock more frequently
during dull, rainy weather or following heavy frosts.
(Also refer to ‘Pesticide residue risks’, page 69).
Failing canola crops can be grazed, but care must be taken when
introducing stock.
Photo: J. Edwards, NSW DPI
Canola best practice management guide
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