HEAL ▶▶▶TH
cause is identified and corrective measures implemented as soon as possible to enable the bird to regain optimum gut health. Mycotoxins, coccidiosis and dysbacteriosis can reduce gut integrity and damage the intestinal epithelium, leading to decreased absorption and digestion of nutrients and increased intestinal barrier permeability which can lead to wet litter. When the gut structures are damaged, undigested nutrients can pass into the caeca providing a nutrient source for the microbial population residing there. Often, potentially pathogenic organisms are found in the caeca and this nutri- ent source allows them to replicate to numbers large enough to cause imbalances in the microbiota which then impacts performance and litter conditions.
Intestinal worms can be an issue when birds have contact with grass, soil and faeces.
are limited in a cage system. These include running, flying, dust bathing, beak cleaning, preening and stretching. This in- creased movement can raise the metabolic energy needed by the hen which can be further affected by adverse weather conditions. The bird will need to increase its feed intake to meet this heightened energy requirement. Otherwise energy will be diverted away from maintenance and egg production. This means it is vital that the bird has optimum gut health, maximising its intestinal surface area to allow for efficient nu- trient absorption and improved feed utilisation. An activated immune system requires both energy and nutrients which are repartitioned from production. With the greater chances of cage-free birds encountering pathogenic bacteria, the bird must have optimum gut health and microbiota as they play a role in modulating the immune system by preventing mucosal infections.
Wet litter In cage-free systems layers have more contact with litter than when housed in cages. This means that wet litter becomes a greater concern. Wet litter and high ammonia content can lead to footpad dermatitis and bumblefoot, a painful footpad infection. While uncommon in furnished cages, the frequency of bumblefoot can be several times greater in litter-based houses. Many factors may contribute to wet litter, includ- ing digestive upset, nutritional imbalance, disease, drinker spillage, inadequate ventilation and humid weather. Both non-pathogenic and pathogenic agents can cause diarrhoea and lead to wet litter. Therefore, it is vital that the underlying
28 ▶ POULTRY WORLD | No. 1, 2022
Disease control Coccidiosis is an enteric condition caused by protozoa of the species Eimeria which infects the intestinal lining and causes damage that enables other pathogenic bacteria to prolifer- ate. The symptoms of coccidiosis are bloody diarrhoea, de- hydration, lethargy, high mortality, poor growth/weight gain and a drop in egg production. Coccidiosis can be controlled via ionophores and chemical compounds added to the feed that inhibit oocyst development. However, resistance and tolerance can develop with these anticoccidials, so they need to be used in cycles to be effective. Another way to control coccidiosis is via a coccidia vaccination programme that de- velops immunity against coccidiosis. Having increased access to litter increases the exposure of cage-free birds to coccidia. However, layers are commonly vaccinated for coccidiosis, especially in cage-free systems. Therefore, they will have immunity by the time they are on the layer farm.
Worms Intestinal worms can be an issue when birds have contact with grass, soil and faeces. Therefore, exposure to intestinal worms is likely in a barn or free-range system. Worms dam- age the bird’s gut, resulting in reduced performance. Three main worms that may cause problems in cage-free birds are roundworms, hairworms and caecal worms. Worms can carry other parasites, like Histomonas, which caus- es blackhead. Blackhead disease (histomoniasis) is a perti- nent poultry disease caused by a protozoa that can be spread to the bird through roundworm. Healthy birds become infect- ed when they eat food, invertebrates (such as earthworms) or ingest bird droppings contaminated with the protozoa. Direct bird-to-bird transmission can also occur within a flock. Chick- ens infected with blackhead disease are usually listless and have drooping wings, unkempt feathers, yellow droppings and reduced egg production. It is essential that birds infected with blackhead are wormed to kill the worms. It is vital that birds are monitored for worms and wormed effectively before moving them to laying accommodation prior to the onset of lay and during lay, to reduce build-up on pasture.
PHOTO: JACK CAFFREY
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