Parasitic Control in Cattle
Gut worms impact directly on animal health, productivity and, ultimately, profitability. All cattle in the UK are affected by gut worms, the commonest being Ostertagia ostertagi and Cooperia oncophora.
First-season grazing calves are most susceptible to gut worm infection and show signs of parasitic gastroenteritis (PGE). Ostertagia species, the most harmful gut worms, inhabit the abomasum (true stomach) and can cause two distinct clinical syndromes:
- Type I disease, which usually occurs from mid-July onwards in intensively grazed calves and
- Type II disease, observed in yearlings in late winter/spring. The latter results from the re-emergence of arrested larvae ingested during the previous autumn. Clinical signs of infection are characterised by profuse watery diarrhoea, anorexia, lethargy and ill thrift. Sub-clinical, low grade infections can lead to losses of 30 - 60 kg in body weight gain in untreated beef cattle during their first 12 months compared to anthelmintic treated stock. In addition to reduced weight gains, PGE can significantly reduce milk output from dairy stock, and affect reproductive performance and carcass quality.
The financial cost of PGE in cattle is difficult to calculate. Costs include treatment, increase in labour to administer the treatment as well as overall animal health and production losses; together this has been estimated to be up to £40 per head.
Treatment: Over the last 25-30 years, and with the advent of extremely effective anthelmintic drugs used in combination with pasture management, producers have successfully negated the impact of parasites in their cattle to maximise profits. Unfortunately, although the routine use of effective anthelmintics has been shown to maximise productivity in dairy and beef cattle it is not, by itself, a sustainable solution with increasing reports of anthelmintic resistance in anumber of cattle gut wormspecies.
Results from a small scale survey conducted at Moredun Research Institute on the efficacy of ivermectin in first-season grazing cattle suggest that reduced efficacy is an issue on some farms. The survey showed that on 8 out of 15 farms tested there were signs of anthelmintic resistance against the ivermectin based products againstCooperia For two of these farms, the worms were further tested at Moredun and were shown to be resistant to both ivermectin and moxidectin.
Quarantine: Failure to effectively quarantine treat infected animals has shown to be one the most important factors in the spread of anthelmintic resistance in infected sheep and cattle. In Moredun’s survey, over a third of respondents did not quarantine treat newly purchased and transient stock with anthelmintic and, of those administering quarantine treatments; over half administered only a class of anthelmintic such as ivermectin.
The current best practice advice for quarantine treatment against gastro-intestinal roundworms is the administration of a benzimidazole (1-BZ) and a levamisole (2-LV) product administered sequentially (NOT COMBINED TOGETHER), keeping the treated animals off pasture for 4 – 5 days (ensuring they have access to food and water) and then grazing them on pasture contaminated with worms after drenching. Ideally treatment efficacy should be assessed 14 days post treatment to ensure that it has been effective.
Monitoring: Large volumes of data are generated on individual farms each year; for example, milk output, live-weight gains and finishing times, animal losses, pasture condition, anthelmintic treatment frequencies and dates of administration. This information can, with a small amount of additional information such as targeted faecal worm egg counts (FWEC), be used by cattle producers and their vets/animal health advisors to evaluate herds and allow them to develop sustainable worm control strategies. The cost of generating this infomation is low in comparison to the costs and consequences of ineffective anthelmintic treatments.
Studies have confirmed that information generated from pooled/composite faecal samples, if generated accurately, can be provide a good indicator of the need to treat animals, particularly in first-season grazing cattle, as well in determining if treatments have been effective. Another area where improved monitoring could prove invaluable is with post drench efficacy checks (PDEC): such services are now commercially available throughout the UK.
Control of Cattle Parasites Sustainably (COWS) is an industry stakeholder group which aims to promote best practice in the control of cattle parasites. It has a wealth of free information for vets, SQPs and farmers about how to control parasitic gut worms and liver fluke in cows. For more information - visit the COWS website
Not a Member?
Moredun membership allows you to keep up to date with the latest advances in livestock health. You can join or renew your Moredun membership online.
Not a Member?
Keep up to date with Moredun's latest research advances by becoming a member now. Join now