Management strategies for cattle
There are many ways of managing cattle grazing OC-contaminated land. Even properties with a high proportion of contaminated land can continue to graze cattle provided management strategies are adopted that minimise OC residues in animals prior to sale for slaughter.
Given the capacity of an animal to fatten is the guiding principle in managing OC residues, the preferred enterprise type for contaminated land is the production of weaners as store cattle to be fattened on residue free land. DPIRD will not allow cattle to be finished and sold for slaughter directly from OC-contaminated land.
Pastures and crops can be manipulated to take advantage of the growth opportunities of store cattle. Also a change to late calving (i.e. after the break in the season) can ease supplementary feeding cost pressures and reduce OC intake as pasture coverage is increased.
For properties with large areas of contamination, a change to the marketing of yearlings instead of weaners may be a cost effective approach to the management of animals with residues. If this enterprise was adopted, the number of breeders would need to be reduced to allow for the carry-over of weaners into yearlings.
Grazing strategies
There are two grazing management strategies for cattle kept on OC-contaminated land. The first strategy is aimed at maintaining cattle OC residues below the MRL. The other strategy allows some animals to have residues in excess of the MRL. These animals are then ‘cleaned’ prior to slaughter.
- Strategy 1: Nil OC residues in the herd – cattle are only permitted to graze areas with OCs for short periods when residue uptake is minimal. Pasture coverage should be 100% and at least 5cm high when the cattle are removed.Hay should not be fed in these paddocks. The herd should be varied regularly to minimise uptake. Cultivated paddocks or where pasture coverage is incomplete are not suitable for this strategy.
- Strategy 2: Some cattle with OC residues – one herd is preferentially used to graze the contaminated area for extended periods. The pasture should be maintained at least 5cm high when grazing. Breeding cows and replacement heifers are generally used for this purpose. Any animals kept on the OC-contaminated land must be ‘cleaned’ prior to sale for slaughter or sold with DPIRD permission to others to fatten.
Industry and government requirements for grazing cattle on OC contaminated land
Western Australian biosecurity legislation introduced in 2013 puts in place additional regulations related to the management of OC-contaminated land and any agricultural products, including cattle produced on this land.
Under the legislation, owners of OC-contaminated properties are issued with a residue management notice which gives directions in relation to land management. This includes disclosure of the residue management notice to potential land buyers.
Livestock owners who graze cattle on OC contaminated land are issued with a residue quarantine notice which gives directions in relation to the management of exposed cattle. A property management plan is also issued as part of the residue quarantine notice. The property management plan stipulates grazing management strategies to minimise the risk that cattle with OC residues in excess of the MRL are slaughtered for human consumption.
Livestock owners issued with a residue quarantine notice must be a member of Livestock Production Assurance (LPA) program and adhere to the food safety principles of the program including the minimisation of residue risk in livestock. LPA regularly conducts on-farm audits of the property management plan and elements of the LPA food safety or QA program. LPA auditors report any non-compliance with the property management plan to DPIRD for action. The cost of membership of LPA and the auditing of the property management plan is borne by the owner.
Testing requirements
Soil testing
Soil testing can be a practical guide to indicate the level of OC contamination and degradation in a paddock over time. However, soil test results may not always reflect the true contamination status of the area tested as OCs are not evenly distributed, variably break down and concentration levels may change depending on geographic location, soil type and enterprise activity.
Where there is suspected OC contamination on land not previously known to be contaminated, soil testing will be conducted at DPIRD’s expense. DPIRD may also conduct testing on known OC contaminated land, to determine breakdown rates.
In all other soil testing scenarios, land owners will be responsible for the costs. Land owners can request DPIRD to interpret and review soil test results.
Fat testing
Livestock owners grazing cattle on OC-contaminated land are required to undertake on-farm fat biopsy testing of a representative sample of animals as per their agreed property management plan. This testing is conducted at the owner’s expense. Contact your local veterinarian to undertake fat testing.
Where a livestock owner has established a record of satisfactory testing results, ongoing testing requirements will be minimal and usually only at slaughter. The owner is responsible for the lab costs. Dry cows, bulls and animals in poor body condition should not be sold for slaughter without being fat tested prior to sale. If in doubt about the OC residue level in an animal, fat test prior to sending for slaughter.