Monitoring worm burdens in cattle
Monitoring worm burdens through worm egg count tests in cattle following the recent break in the season.
Recent rainfall and warmer conditions means that worm burdens will be increasing. It is important that you monitor young cattle in particular for signs of worm infestation. Cattle that are low in condition as a result of drought and now grazing short, green pasture are at risk of contracting worms.
Worm Egg Counts
Zoetis provides a worm egg count (WEC) monitoring service, via your local Elders store, which is conducted by an independent parasitology laboratory. The sampling process involves collection of faecal samples from 10 animals at random in the target group of cattle. To date, over 70,000 samples have been tested, collected from cattle around Australia. This service provides information to the producer on the number of worm eggs per gram of faeces in sampled cattle. When there are a sufficient number of worm eggs present, these samples are cultured to larvae stage and the worm species determined. This provides valuable information allowing cattle producers to make informed drenching decisions, such as selection of the drench that has the best efficacy against the worm burden present, and determining the best timing of drench treatments. These results have been summarised via Wormtrax™ – visit the Wormtrax website and enter your postcode.
Sampling young and occasionally older cattle
Sampling has typically been biased towards weaner and growing cattle as these are the animal groups at most risk of significant parasite infections. Older cattle that have been born and bred in these same regions and had previous exposure to the mix of internal parasites common to these areas should have developed effective immunity. It is important to note though, that older cattle may be at risk of parasitism if they have had no or limited exposure to worms as young animals due to drought or if they have been relocated from drier inland areas where worm burdens are lower. In these circumstances, monitoring older cattle can be of value and some strategic drenching may be required until they develop immunity.
Review worm burden results
Zoetis worm egg count data show that worm egg counts and worm types vary significantly across Australia. The most common parasite type encountered is Cooperia spp (small intestinal worm) followed by either Haemonchus spp (Barber’s pole worm) and Oesophagostomum spp (Large Bowel worm) in summer rainfall regions, or Ostertagia spp (Small brown stomach worm) and Trichostrongylus spp (Black Scour worm) in winter rainfall regions.1 While the wormtrax data can provide a guide for your region, the only way to know for sure what is happening on your farm is to test the right groups of animals.
Select the most suitable drench
Cooperia spp (small intestinal worm) are the most difficult of this mix of worms to control with the macrocyclic lactone group of chemicals, which includes ivermectin, abamectin, moxidectin, eprinomectin and doramectin. Of this group, doramectin, the active ingredient of Dectomax®, gives the most sustained and effective control of Cooperia spp as well as controlling the common worms listed above providing uniform levels of sustained activity across the spectrum of worm types.
Dectomax Pour-On applied in the autumn months can be used to provide strategic control of buffalo fly, especially as an end of season treatment after use of SP/OP based fly tags or backrubbers. Dectomax injectable and Pour-On also control cattle tick where this parasite is a concern.
For further information on the worm egg count testing program or for advice on appropriate drench selection offered by Zoetis, speak to your local Zoetis Professional Sales representative.
1. Taylor LF, Hodge A. Descriptive findings from analysis of a large database of cattle worm egg count and larval culture results collected across Australia between 2002 and 2012. Vet. Parasitol. 204 (2014) 269–278.
Article written for the Autumn 2021 edition of Seasons Magazine by Dr Lee Taylor, Senior Veterinary Technical Manager – Livestock, Zoetis.
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