The importance of Haemonchus in cattle

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.

So what is the problem?

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).

When and why do we see Haemonchus?

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.

How do we manage it?

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.

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.

What drench should I choose?

CYDECTIN LONG ACTING INJECTION protects against Barbers pole worm for at least 120 days, the longest protection of any product, while CYDECTIN^® POUR-ON protects for at least 28 day.

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.

1. Eggington, AR; McCosker, TH; Bainbridge, MH (1984) Animal Production in Australia Vol. 15.
2. Hutchinson, GW; Cook, LA; Colditz, P; Copeman, DB (1980) Aust. J. Agric. Res. 31: 1049-56.
3. Winks, R; Burns, MA; Berrie, DA; East, IJ; Kelly, JG; Bremner, KC (1987) Aust. J. Exp. Agric., 27: 189-93
4. Fiel CA, Saumell CA, Steffan PE, Rodriguez EM (2001) Resistance of Cooperia to ivermectin treatments in grazing cattle of the Humid Pampa, Argentina. Vet Parasitol 97:211–217.
5. Lyndal- Murphy M, Rogers D, Ehrlich WK, James PJ, Pepper P, Reduced efficacy of macrocyclic lactone treatments in controlling gastrointestinal nematode infections of weaner dairy calves in subtropical eastern Australia (2010). Vet Parasitol 168:146-150.
6. de Soutello et al. 2010, Evaluation of reduction in egg shedding of gastrointestinal nematodes in cattle following administration of anthelmintics, Rev. Bras. Parasitol. Vet., Jaboticabal, 19-3: 183-185.
7. Lyndal-Murphy M, Rogers D, Ehrlich WK, James PJ, Pepper P, Reduced efficacy of macrocyclic lactone treatments in controlling gastrointestinal nematode infections of weaner dairy calves in subtropical eastern Australia (2010). Vet Parasitol 168:146-150. 8 Yazwinski TA, Tucker CA, Powell J, Reynolds J, Hornsby P, Johnson Z: Fecal egg count reduction and control trials determinations of anthelmintic efficacies for several parasiticides utilizing a single set of naturally infected calves. Vet Parasitol 164: 232-241, 2009.