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MOO Tests show four out of five dairy herds are affected by gutworm

Merial-Sanofi_Logo_rgbThe latest MOO Test figures from Merial Animal Health suggest that the productivity of four out of five UK dairy herds is compromised by high levels of gutworm.

Merial Animal Health has been helping dairy farmers to assess the level of gutworm challenge in their herds since 2009 by supporting and promoting MOO tests. The test measures the level of antibody to gutworm (Ostertagia ostertagii) that is present in a bulk milk sample and can determine if the herd has been exposed to low, medium or high challenge.

Data from five years of MOO Tests shows that whilst there was a steady reduction in the number of herds with a high challenge between 2009 and 2013, the figure rose in 2014. In 2009, 93% of herds tested high and by 2013 this had fallen to 71% but this rose again to 88% last year.

Whilst these figures show an overall reduction in challenge since 2009, levels of gutworm across the UK dairy herd are still very high. Those animals affected will suffer from the negative impact of a parasite burden on productivity and fertility.

Between 2009 and 2014 nearly 900 dairy herds across the UK have been tested. During that time several counties had significant numbers of herds with high gutworm challenge results. This included Cheshire (85%), Cornwall (93%), Cumbria (91%), Dyfed (92%), Lancashire (90%), North Yorkshire (83%), Shropshire (86%), Somerset (86%), and Staffordshire (83%).

Sioned Timothy, veterinary adviser for Merial Animal Health, said: "Gutworm can significantly reduce the productivity of the herd. Although adult dairy cows develop immunity to gutworm that makes them resilient to outward clinical signs of infection, it does not prevent them from becoming infected with Ostertagia ostertagi. This parasite burden can reduce milk yield by as much as 2.6 litres per cow per day1"

She continued: "Gutworm may also have a negative impact on fertility. Removing damaging gutworms from dairy cows may improve their fertility and has been linked to reduced calving to conception intervals and improved conception rates2 to levels comparable with animals without a gutworm burden."

Calving is another key period in the production cycle. Optimising cow and heifer management during this period is critical to the animal's health and productivity throughout the subsequent lactation. Cows treated for gutworms around the time of calving have been shown to increase their grazing time by almost an hour compared to untreated cows3. Improved appetite and higher dry matter intake helps cows to bridge the energy gap; maximising their production, and reducing the time it takes to get them back into calf4."

Ms. Timothy concludes: "The MOO Test figures show that the UK dairy herd continues to be affected by high levels of gutworm challenge. At a time when maximising productivity is vital to dairy business success, farmers should seriously consider testing their herd this autumn and develop a treatment plan with their vet or animal health adviser based on the result."

MOO tests will be available in autumn 2015. Farmers should ask their vet or animal health adviser for more information. The results of MOO tests are sent to both the farmer and their vet or animal health advisor, to enable them to determine the best course of action and treatment.


1. Reist et al, Effect of eprinomectin treatment on milk yield and quality in dairy cows in South Tyrol, Italy. Veterinary Record 2011 168, 484-487 Vet Rec 2002151:377-380

2. McPherson  et al. Proceedings of the American Association of Veterinary Parasitologists. 44th Annual Meeting, New Orleans, Louisiana, USA, 1999 Abstr. 28.

3. Forbes et al. Behavioural mechanisms underlying production responses in dairy cows treated with eprinomectin. 19th WAAVP Congress 2003, New Orleans

4. Sanchez et al. The effect of eprinomectin treatment at calving on reproduction parameters in adult dairy cows in Canada. Preventative Veterinary Medicine 2002 56:165-177