Unfortunately, the damaging effects of this roundworm on cattle production are often underestimated. Haemonchus is a problem throughout northern New South Wales, Queensland, Northern Territory and the Kimberly. In some seasons with good summer rainfall, the problem can spread into southern Australia.
Barber’s pole worms are relatively large worms that live in the fourth stomach and feed on blood by attaching to the gut wall. Visual signs of Haemonchus infection include bottle jaw, weakness, anaemia and eventually death. Research in the Northern Territory has shown that treatment for Haemonchus at both marking and weaning significantly reduced post weaning dry season deaths compared with cattle treated only at weaning or not treated at all1.
More commonly, Haemonchus reduces growth rates, causes ill-thrift and weight loss. Unfortunately, the effects of infection are often more severe if the infection is combined with either/both Oesophagostomum or Bunostomum species which are widespread.
Research on the Atherton tablelands shows that worms can reduce weight gain in untreated cattle by 50kg over 48 weeks compared to cattle treated every three weeks2. In south-east Queensland, both Hereford and Brahman cross-bred weaners had lower weight gains over 8 months (36kg and 20kg respectively).
Warm and wet climates are the most favourable for Haemonchus development, with favourable conditions allowing rapid build up of numbers due to its prolific egg laying capacity. Figure 1 shows how larval pasture challenge increase throughout summer and peaks in autumn. Parasite burdens increase throughout autumn and reach their peaks during winter. Adequate levels of feed during spring and summer help reduce the challenge. As protein levels in feed reduces in autumn and winter, worm burdens and production loss increase.
As with all cattle parasites, management should aim to reduce exposure of cattle, particularly young cattle to parasite challenge. This can either be done through providing clean paddocks (no stock for up to 6 months) or by using drenches that have long periods of persistency against Haemonchus.
Cattle show most response to treatment for roundworms when they are treated at either branding or weaning.
|Faecal egg counts (weaners)|
|Worm Species||Eggs per gram faeces|
Treating calves at marking with CYDECTIN® LONG ACTING INJECTION in summer will have the greatest impact on reducing pasture contamination. Depending on season and age of cattle, this control strategy may all that is required before stock are turned-off. Other treatments may be required dependant on animal condition, growth rate or when worm egg counts are significant.
Not only do these products provide the longest level of protection, both local and international research shows that Cydectin offers the greatest level of potency where resistance is developing.