20/12/2019

Team publications 2019

The Uplands team are pleased to deliver some new research. Please see below abstracts from two of our published papers from this year. Get in touch if you would like a full copy of the paper by emailing uplands@gwct.org.uk.

Baines, D., Newborn, D. & Richardson, M. (2019). Are Trichostrongylus tenuis control and resistance avoidance simultaneously manageable by reducing anthelmintic intake by grouse? Vet Record, 185: 53-60.

ABSTRACT

Benzimidazole-based anthelmintics bound to grit (medicated grit) are annually prescribed on request by veterinary practices to grouse managers to control Trichostrongylus tenuis an intestinal parasite of red grouse Lagopus lagopus scotica. Those prescribing medication typically do without knowledge of parasite loads and hence often prescribe when loads are low and unlikely to impact the host. Inappropriate use of anthelmintics in livestock has led to development of parasite resistance to anthelmintics. To encourage grouse managers to reduce anthelmintic use, the authors experimentally withdrew medication from parts of eight moors. The authors monitored parasite and grouse responses by counting eggs and adult worms and grouse mortality and breeding success. Rapid increases in parasite egg counts in early spring culminated in resuming medication at three wet, blanket-peat sites; one in the first spring and two in the second. Medication was restored, despite low parasite counts, at a fourth moor. On the remaining four moors, drier heaths in the east, parasite levels remained low, were not associated with grouse mortality, but breeding success was 16 per cent lower in years without medication. Better parasite monitoring by grouse managers and vets alike may reduce anthelmintic use, helping prevent drug resistance, but this may be off-set by reduced grouse productivity.

Baines, D., Newborn, D. & Richardson, M. (2019). Correlates of pathological lesion associated with respiratory cryptosporidiosis prevalence in shot red grouse Lagopus lagopus scotica from moors in northern England. Avian Pathology.

ABSTRACT

Infection of wild red grouse Lagopus lagopus scotica by Cryptosporidium baileyi was first diagnosed in 2010. Within three years, signs of infection were reported from grouse on half of all grouse moors in northern England, bringing severe concerns of economic losses to grouse shooting. A total of 45,914 red grouse shot from 10 moors in northern England between 2013 and 2018 were visually screened for signs of respiratory cryptosporidiosis. Prevalence varied with age, being twice as high in juveniles (4.5%) as in adults (2.4%). It also varied nine-fold between moors and three-fold between years. Prevalence was highest in grouse shot later in the shooting season. Our results are consistent with the concept that disease incidence is highest in naïve juveniles that have previously not been exposed to infection, with prevalence dropping as birds develop immunity. We found no evidence of increased prevalence over time, and fears of escalated disease prevalence, bringing with it increased mortality and lowered productivity, that may have significant impacts on the economic viability of shoots, have not yet been realized. We recommend continued annual screening for clinical signs amongst shot birds, better hygiene associated with potential reservoirs of infection, and practices that both improve the detection and selective culling of diseased individuals and generally reduce overall grouse densities.

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