Intestinal Worms - A Familiar Feature
Intestinal worms are a familiar feature in many poultry systems, particularly where birds have access to range or are kept on the same ground for extended periods. Because they are so common, low level worm challenges are often accepted as part of the job.
In reality, even modest burdens can quietly undermine flock performance and bird welfare long before obvious problems are seen.
Most worm species affecting poultry live in the gut and interfere with digestion and nutrient uptake. Birds may continue to eat well, but the feed is used less efficiently, which shows up as slower growth, poorer feed conversion or a gradual drop in egg numbers. In laying flocks, egg quality is often the first warning sign, with more seconds, paler shells and lighter yolks appearing while birds still look outwardly healthy. Flock uniformity can also suffer, with a widening gap between the best and worst birds.
A range of different worms may be involved. Large roundworms such as Ascaridia galli are common and can reach several centimetres in length. Hairworms, Capillaria species, are much smaller but can cause significant irritation to the gut lining. Caecal worms, Heterakis gallinarum, usually cause little direct damage themselves but are important because they can carry Histomonas meleagridis, which leads to blackhead disease. Gapeworm, although less frequently seen, can cause severe respiratory signs, especially in younger birds. Tapeworms are also encountered, particularly in free range systems, and rely on insects or slugs to complete their life cycle.
The challenge with worms is that infection pressure builds up over time. Eggs are shed in droppings and can survive for long periods in damp soil and litter. Birds become infected by ingesting these eggs directly or by eating infected insects and earthworms while foraging. Wet weather, poached ground, poor litter quality and repeated use of the same range areas all increase the risk, particularly during winter housing periods followed by turnout.
Clinical signs vary depending on worm burden but often include poor growth, uneven birds, diarrhoea, weight loss and pale combs linked to anaemia. In breeder flocks, reduced fertility and hatchability are frequently associated with ongoing worm challenge. The additional stress placed on birds can also increase feather pecking and leave flocks more open to secondary disease.
Managing worms effectively requires a planned, preventative approach rather than reacting once problems are obvious. Diagnosis can be confirmed through post-mortem examination or faecal egg counts, but routine monitoring by opening a small number of birds can be just as valuable. Licensed anthelmintics such as flubendazole, fenbendazole, levamisole or piperazine remain effective tools when used correctly, although it is important to remember that most products targeting roundworms are not effective against tapeworms. Withdrawal periods for eggs and meat must always be observed.
Good control also relies on reducing reinfection. Maintaining dry, friable litter, managing range condition, rotating paddocks, controlling insects and avoiding excessive stocking pressure all help to lower worm challenge. When combined with a suitable treatment programme, these measures support better gut health, more consistent performance and improved flock welfare.
For practical advice tailored to your system, your Crediton Milling poultry representative can help review parasite control, nutrition and overall flock management.
