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Release Season, Worm Burdens and Hexamita

Dr Kenny Nutting BVetMed MRCVS, St David’s Game Bird Services

Usually, this time in the release season, we are slowly starting to wind down on releasing. However, this year, of course we are still in the peak of birds going out, and we expect there still to be releasing of birds throughout August, resulting in a delayed start to the shooting season this year. Chicks are still being placed on the ground and so the quality is obviously starting to deteriorate, given the normal time of year and the conditions at which point those eggs were laid were quite variable at the time. This has an impact on both egg quality and hatchability and therefore chick quality.

Hexamita is also maintained due to uneven weather conditions we have been experiencing through this period. Hexamita can cause very high mortality in rear and the post release period. Especially when birds are stressed. Birds show a watery diarrhoea and serious weight loss, which causes dehydration. Birds should have easy access to plenty of drinking water and prevention plans should entail good hygienic management practices and reduction of stress as much as possible.

With the extended rearing season and therefore release period, we are expecting that the worm burdens in release will be higher than normal, given that is most likely going to be wetter than normal when the birds are going into the pens. It will be even more important to be on top of worms, particularly in those birds which are being released later than normal, as they are at more risk from adverse climate conditions. We must always remember the withdrawal periods on any wormers used.

Temperature regulation is usually the main issue during the warmer spells, followed by the wet weather making it difficult to keep sheds bio secure due to the amount of mud on the fields. Typically, dry spells followed by lots of rain can cause an increase in worm burden amongst the birds, and often a heavy worm burden can be a gateway to the introduction of further disease as the bird is already compromised.

We recommend speaking with your vet regarding worm treatments if you are concerned about your flock, and they can advise the best preventative treatment where necessary.

Finally, given that many people have made the decision to overwinter birds this year it will be during this period that people will be extending their runs to keep the birds on the rearing field for longer, or will be looking to vaccinate and move the birds to an overwintering quarter. This is really dependant on which batch of birds the breeding stock has been taken from.

After a successful online discussion event we organised in June, we’re keen to hear your thoughts on future online discussion events and if there are topics or discussion areas you would like us to focus on. To register your interest, please email us on –

Originally written for July’s monthly feature of Countryman’s Weekly – ‘The Vet Diaries’