SKIN AND FEATHERS
16:09 05 September 2011
VICTORIA ROBERTS looks at conditions that can affect your hens, and how to deal with them
Avian skin is more delicate and thinner than mammals’ and is attached to muscles in relatively few places but firmly attached to the skeleton extensively on the foot and carpus (the end of the wing). Avian skin heals very quickly if damaged.
Feather follicles are arranged in tracts; the elevation is controlled by muscles under the skin with some areas free of feathers which helps with thermoregulation (keeping to a normal temperature when environmental temperature changes) as they have no sweat glands. When a hen is broody, a bare area of skin on her breast, the brood patch, is in contact with the eggs to maintain moisture and temperature. Four week old chicks develop a synovial bursa normally at the front end of the breast which only becomes a problem if it gets infected by being on damp litter. Adult Old English Game have few feathers on this area normally and the Transylvanian Naked Neck has half the number of feathers of other chickens in order to cope with a hot climate, but they look a little strange with just a cap and gown – all exposed skin being bright red. Normal skin colour is either white (e.g. Sussex), yellow (eg Rhode Island Red) or black (e.g. Silkie). Leg colour again depends on breed or colour of plumage, and in breeding cockerels there is a red blush down the legs. Yellow leg colour can fade in laying hens as the pigment goes into the yolk.
The comb and wattles are very well supplied with blood vessels and, in a fit bird, are bright red (except dark faced breeds). Earlobes are either white, red or blue, depending on breed, and a white earlobe indicates the laying of a white shelled egg as they are genetically linked.
The beak is a structure made of hard keratin and continually grows throughout the chickens’ life.
Claws are also of keratin and sometimes need trimming if there is no access to hard surfaces. Spurs can be found on both male and female chickens. A short round spur denotes the age of a male as less than six months. A longer, sharp spur (about 1”, 2.5cm) denotes a bird of approximately one year old and spurs increase in length by about ½“ (1cm) every year. Scales on legs are moulted once a year and should be smooth and shiny. Foot pads are like shock absorbers but can become infected in poultry.
There are glands in the ear canals which exude wax: the ear canals themselves are concealed by small tufty feathers. The preen gland is a small, nipple-like protruberance just above the tail. It exudes an oily substance which birds then preen over their feathers to help weatherproof them, gain vitamin D when exposed to sunlight and keep feathers plus beak and leg scales in supple condition.
• Pale: the bird may be anaemic, so check for red mite infestation.
• White flakes on one side only: fungal infection (known as Favus) obtained from old wood, similar to ringworm, treat with long-acting athlete’s foot cream.
• Purple: the circulation is impaired which usually means a weak heart. Some birds manage well until stressed such as being handled or washed for a show. Medication is available from your vet.
• Black: this may be dried blood, so wash gently. If in winter it may be frostbite on the spikes of the comb and these can drop off. Cover other large combs at risk with Vaseline.
• White spots then blisters and scabs: fowl pox virus. Uncommon and may be vaccinated against. Pigeons are carriers, chickens, turkeys and quail affected. Spread by biting flies.
Breast blister: check litter is dry, then should reduce by itself.
Flank wounds: mainly in soft feathered hens such as Buff Orpington. Check for overgrown spurs or claws. Fit with a ‘saddle’ in the breeding season or keep male separate except for a few minutes a day to mate with the hens.
Ear infection: the inside of the ear canal is skin which produces wax, if infected, this goes cheesy and yellow, the covering feathers stick out and look crusty. Treatable with veterinary dog ear drops.
Bumblefoot: swelling of the pad of the foot, infection caused by Staphylococcus bacteria. Check perches are not too high as bruising predisposes, especially in heavy breeds. Difficult to cure as the abscess gets walled off, so no blood supply to take antibiotics to the infected area, poultices seem to be the most effective.
Crossed beak: may be inherited or early trauma. Mild cases can be trimmed but advisable not to breed. Severe cases should be culled as soon as noticed.
Spur overgrowth: can be filed smooth if sharp point. A bird may not be able to walk as spur hits other leg, or the spur can crow back into the leg, so keep checking. There is a large artery in the spur so do not attempt removal without cautery.
Claw/beak overgrowth: trim with guillotine type (prevents splitting) dog nail clippers to normal shape, being aware of the quick.
Vent pecking: cannibalism usually occurs through overcrowding and/or heat stress which in the warmer months is worsened by feeding maize (very heating food).
Erysipelas: land with a history of sheep or pig production is liable to have the erysiplas bacteria on it and affects principally turkeys over 13 weeks, pheasants and occasionally ducks, geese, chickens and quail. The organism can survive for years in the soil, so be aware also that problems may occur if a pond has been dug or topsoil imported. It enters birds through breaks in the skin, so fighting or biting insects can be a cause. Onset of disease is rapid with birds found dead in good condition. Heart disease is also caused by erysipelas. Penicillin injection will bring an outbreak under control and there is a vaccine for turkeys. The danger of this disease is that it is zoonotic and can cause skin rash and cellulitis (swelling) with possible heart disease for a person handling infected carcases and sustaining an injury, such as a cut.
Feathers are used for warmth, courtship and territorial displays and for lining the nest.
There are four types:
1) Contour feathers which cover the body and include the wing feathers, the wing coverts, the tail feathers and the small feathers covering the ear canal. When these contour feathers emerge from the feather follicle they have a pulp cavity (calamus) with an artery and vein and as the feather matures this is resorbed, creating a hollow tube: a broken growing feather will therefore bleed profusely, but mature feathers may be cut (as in wing clipping) with no damage. The strength and waterproofing of the feather is maintained by the barbs interlocking: as the bird passes the feather through its beak when preening, the barbs are relocked.
2) Very close to the follicle of each contour feather is a delicate filoplume which has many nerve endings and helps to keep the contour feathers in optimum positions. Plucking feathers on a live bird is therefore a painful process. There are also sensory bristle feathers but not as many as the filoplumes.
3) Semiplumes are fluffy feathers which act as thermal insulation and increase buoyancy in aquatic birds. Silkies have only semiplumes, leading Marco Polo in the 13th century to describe them as hens with wool on their backs.
4) Down feathers include those on newly hatched chicks for warmth, the colour of which in pure breeds is definitive for a breed. Adult chickens have some in otherwise featherless areas.
The colour of feathers is due to a combination of pigment and structure. Melanin pigments occur in granules in the skin and feathers and produce yellow, red-brown, brown and black. Carotenoids, derived from plants, produce yellow, red and orange in fat globules in the feathers. White colour in birds is caused by the reflection and refraction of all wavelengths of white light striking the feathers and iridescence by varying the structure of the feather.
Sexing of hens (not Silkies) can be achieved by observing the shape of the growing feathers on birds that are about 8-10 weeks old. The rounded subadult feathers are replaced in the males by sharply pointed and shiny feathers between the shoulder blades and above the tail. Adult plumage is attained by 18 weeks in most chickens.
Moulting is the shedding and annual replacement of feathers, usually after the breeding season. The new feathers push out the old ones from the base of the follicle and are vulnerable to damage while growing. Hens should moult swiftly once a year. Sometimes the tail feathers of poultry can get stuck in the feather sheath. This can be gently removed with a thumbnail to prevent damage to the emerging feather. Old feathers can change colour (fade or go brown) due to weathering and wear, so the new set usually looks very clean and smart. If feathers appear which are a totally different colour from before, the bird may have nutritional deficiencies, or the ovaries may be damaged and it may produce a male set of plumage. This is fairly common in hens, pheasants and ducks and is known as intersex. The birds usually neither lay eggs nor mate subsequently and it is generally irreversible. Sebrights and Campines are henny feathered and thus do not have the male feather characteristics this is a feature of these breeds.
Hens like to dustbathe as it keeps their feathers in good condition and helps to remove any lice. Dry ashes, sand or dry soil is appreciated, so ensure a dry area in winter.
Wing clipping is used to prevent birds from flying over a fence by unbalancing flight. The primaries are cut with sharp scissors close to the coverts on one wing only. This does not damage the mature feather follicle.
Feather pecking: also caused by overcrowding and/or heat stress if around the tails or on the wings. Some breeds peck the throat area or around the neck or shoulders. The culprit is often the one with all its feathers. Check that feathers are not being removed by a bird pushing through a wire mesh to get to grass. Remove culprit and only replace when all feathers have regrown. After weeks of feather growth it only takes minutes for them to be plucked again.
Moulting: normally takes 3-4 weeks in late summer/early autumn. If longer, check nutrition and mineral content of feed. A seaweed supplement is useful as the iodine in it is a precursor of keratin and produces stronger feathers. Stress bars or fret marks will appear on growing feathers following a nutritional crisis (lack of food, bad weather, bullying), but at next moult will disappear if there is no further insult.
Parasites: see YC 3.
CAPTIONS: In a fit bird, the comb and wattles are bright red. The Burford Brown cock, shown here, is reared at Chatsworth, Derbyshire. The Chatsworth Rare Breeds Farm has a variety of poultry breeds.
Photo: TERRY BEEBE
The beak is made of hard keratin and grows throughout a chicken’s life. This bird is a Blue Breda cockerel
Photo: TERRY BEEBE
Feathers are used for warmth, courtship and territorial displays. This is a Blue Partridge bantam with one of her chicks. Note the striking feather markings. Photo GRANT BRERETON
These are the striking feather markings on a Derbyshire Redcap Photo: TERRY BEEBE