Health management of poultry
- Part 2 -

TC Tolenkhomba / Prava Mayengbam *

A Poutry Farm at Nongpok Sanjenbam village in March 2019 :: Pix - Lamdamba Oinam

Mycoplasma synoviae: Birds infected with the synovitis form show lameness, followed by lethargy, reluctance to move, swollen joints, stilted gait, loss of weight, and formation of breast blisters. Birds infected with the respiratory form exhibit respiratory distress. Greenish diarrhoea is common in dying birds.

Treatment: Recovery is slow for both respiratory and synovitis forms. The most effective antibiotics are tylosin, erythromycin, spectinomycin, lincomycin, and chlortetracycline. These treatments are most effective when the antibiotics are injected.

Prevention: Eradication is the best and only sure way to control

Aspergillosis: Aspergillosis occurs as an acute disease of young birds and a chronic disease in mature birds. Young birds have trouble breathing and gasp for air. Characteristically, there are no rales or respiratory sounds associated with aspergillosis. Feed consumption decreases. Occasionally there is paralysis or convulsions caused by the fungal toxin.

Mortality in young birds averages 5-20 percent, but may be as high as 50 percent. Mature birds also have respiratory distress, reduced feed consumption, and may have a bluish and dark colour of the skin (cyanosis). Nervous disorders, such as twisted necks, may occur in a few birds. Mortality in mature birds is usually less than 5 percent.

Treatment : There is no cure for infected birds. The spread can be controlled by improving ventilation, eliminating the source of the infection, and adding a fungistat (mycostatin, mold curb, sodium or calcium propionate, or gentian violet) to the feed and/or copper sulfate or acidified copper in the drinking water for 3 days. The litter can be sprayed lightly with an oil-base germicide to control dust and air movement of fungal spores.

Prevention: It is important to thoroughly clean and disinfect the brooding area between broods. Use only clean litter, preferably soft wood shavings. Do not use sawdust, litter high in bark content, or shavings that have been wet.

Marek’s Disease: Marek’s disease is a type of avian cancer. Tumours in nerves cause lameness and paralysis. Tumours can occur in the eyes and cause irregularly shaped pupils and blindness. Tumours of the liver, kidney, spleen, gonads, pancreas, proventriculus, lungs, muscles, and skin can cause incoordination, unthriftiness, paleness, weak labored breathing, and enlarged feather follicles.

In terminal stages, the birds are emaciated with pale, scaly combs and greenish diarrhoea. Marek’s disease is very similar to Lymphoid Leukosis, but Marek’s usually occurs in chickens 12 to 25 weeks of age and Lymphoid Leukosis usually starts at 16 weeks of age.

Treatment: none

Prevention: Chicks can be vaccinated at the hatchery. While the vaccination prevents tumour formation, it does not prevent infection by the virus.

Lymphoid Leukosis: The virus involved has a long incubation period (4 months or longer). As a result, clinical signs are not noticeable until the birds are 16 weeks or older. Affected birds become progressively weaker and emaciated. There is regression of the comb. The abdomen becomes enlarged. Greenish diarrhoea develops in terminal stages.

Treatment: none

Prevention: The virus is present in the yolk and egg white of eggs from infected hens. Most national and international layer breeders have eradicated lymphoid leukosis from their flocks.

Infectious Bursal Disease: : In affected chickens greater than 3 weeks of age, there is usually a rapid onset of the disease with a sudden drop in feed and water consumption, watery droppings leading to soiling of feathers around the vent, and vent pecking. Feathers appear ruffled. Chicks are listless and sit in a hunched position. Chickens infected when less than 3 weeks of age do not develop clinical disease, but become severely and permanently immunosuppressed.

Treatment: There is no specific treatment. Vitamin-electrolyte therapy is helpful. High levels of tetracyclines are contraindicated because they tie up calcium, thereby producing rickets. Prevention: Vaccine is commercially available.

Avian Encephalomyelitis: Signs commonly appear during the first week of life and between the second and third weeks. Affected chicks may first show a dull expression of the eyes, followed by progressive incoordination, sitting on hocks, tremors of the head and neck, and finally paralysis or prostration. Some may refuse to walk or will walk on their hocks.

In advanced cases, many chicks will lie with both feet out to one side (prostrate) and die. All stages (dullness, tremors, prostration) can usually be seen in an affected flock. Feed and water consumption decreases and the birds lose weight. In adult birds, a transitory drop (5-20 percent) in egg production may be the only clinical sign present.

However, in breeding flocks, a corresponding decrease in hatchability is also noted as the virus is egg- transmitted until hens develop immunity. Chickens which survive the clinical disease may develop cataracts later in life.

Treatment: There is no treatment for outbreaks. Infected birds should be removed, killed and incinerated. Recovered chicks are unthrifty.

Prevention: Vaccine is available.

Egg Drop Syndrome: There are no reliable signs other than the effects on egg production and egg quality. Healthy-appearing hens start laying thin-shelled and shell-less eggs. Once established, the condition results in a failure to achieve egg production targets. Transient diarrhoea and dullness occur prior to egg shell changes. Fertility and hatchability are not affected.

Treatment: There is no successful treatment. Induced molting will restore egg production.

Prevention: Prevention involves a good biosecurity program.

Fowl Cholera: Fowl cholera usually strikes birds older than 6 weeks of age. In acute outbreaks, dead birds may be the first sign. Fever, reduced feed consumption, mucoid discharge from the mouth, ruffled feathers, diarrhoea, and laboured breathing may be seen. As the disease progresses birds lose weight, become lame from joint infections, and develop rattling noises from exudate air passages. As fowl cholera becomes chronic, chickens develop abscessed wattles and swollen joints and foot pads. Caseous exudate may form in the sinuses around the eyes. Turkeys may have twisted necks.

Treatment: A flock can be medicated with a sulfa drug (sulfonamides, especially sulfadimethoxine, sulfaquinoxaline, sulfamethazine, and sulfaquinoxaline) or vaccinated, or both, to stop mortality associated with an outbreak. It must be noted, however, that sulfa drugs are not FDA approved for use in pullets older than 14 weeks or for commercial laying hens. Sulfa drugs leave residues in meat and eggs.

Antibiotics can be used, but require higher levels and long term medication to stop the outbreak.

Prevention: On fowl cholera endemic farms, vaccination is advisable. Do not vaccinate for fowl cholera unless you have a problem on the farm. Rodent control is essential to prevent future outbreaks.

Omphalitis: Affected chicks may have external navel infection, large unabsorbed yolk sacs, peritonitis with foetid odour, exudates adhering to the navel, oedema of the skin of ventral body area, septicemia and dehydration.

Treatment: There is no specific treatment for omphalitis. Most affected birds die in the first few days of life.

Prevention: Control is by prevention through effective hatchery sanitation, hatchery procedures, breeder flock surveillance, and proper pre-incubation handling of eggs. Mushy chicks should be culled from the hatch and destroyed.

Pullorum: Death of infected chicks begins at 5-7 days of age and peaks in another 4-5 days. Clinical signs - huddling, droopiness, diarrhoea, weakness, pasted vent, gasping, and chalk-white feces, sometimes stained with green bile. Affected birds are unthrifty and stunted because they do not eat. Survivors become asymptomatic carriers with localized infection in the ovary.

Treatment: Treatment is for flock salvage only. Several sulfonamides, antibiotics, and antibacterials are effective in reducing mortality, but none eradicates the disease from the flock.

Prevention: Pullorum outbreaks are handled, on an eradication basis. Breeder replacement flocks should be tested before onset of production to assure pullorum-free status.

Necrotic Enteritis: Rapidly growing young birds, especially chickens 2-12 weeks of age, are most susceptible. Initially there is a reduction in feed consumption as well as dark, often blood-stained, faeces. Infected chickens will have diarrhoea. Chronically affected birds become emaciated. The bird, intestines, and faeces emit a fetid odour.

Treatment: The clostridia bacteria involved in necrotic enteritis are sensitive to the antibiotics bacitracin, neomycin, and tetracycline. However, antibiotics such as penicillin, streptomycin, and novobiocin are also effective. Bacitracin is the most commonly used drug for control of necrotic enteritis.

Prevention: Prevention is directed toward sanitation, husbandry and management.

Staphylococcus: Infections appear in three forms — septicemia (acute), arthritic (chronic), and bumblefoot. The septicaemia form appears similar to fowl cholera in that the birds are listless, without appetite, feverish, and show pain during movement. Black rot may show up in eggs (the organism is passed in the egg).

Infected birds pass fetid watery diarrhoea. Many will have swollen joints (arthritis) and production drops. The arthritic form follows the acute form. Birds show symptoms of lameness and breast blisters, as well as painful movement. Birds are reluctant to walk, preferring to sit rather than stand. Bumblefoot is a localized chronic infection of the foot, thought to be caused by puncture injuries. The bird becomes lame from swollen foot pads.

Treatment: Novobiocin (350 g/ton) can be given in the feed for 5-7 days. Erythromycin and penicillin can be administered in the water for 3-5 days or in the feed (200 g/ton) for 5 days. Other antibiotics and drugs are only occasionally effective.

Prevention: Remove objects that cause injury. Isolate chronically affected birds. Provide nutritionally balanced feed

Management-related Problems

Nutritional problems: Birds that are fed an adequate diet made up from a good commercial feed are unlikely to suffer from nutritional problems unless there are additional factors involved, such as diseases that result in diarrhoea or otherwise interfering with the digestive system.

Stress: Any form of stress may result in a disease outbreak, or diseases in individual birds, as a result of a disease causing organism that is not normally a problem. Any disease will also result in stress, and may therefore increase the potential for other diseases. Stress may result in the immune system not being able to cope with the disease challenge.

Cannibalism and feather picking: Cannibalism is a problem that is particularly associated with large poultry flocks where birds kept in close confinement peck at each other. This can produce significant mortality in the flock when injury results. It will also cause a decrease in egg production as the hen-pecked birds become stressed. Some chickens are more likely to engage in cannibalism than others.

The problem has a range of causes, which are heat without adequate ventilation/nests and nesting areas not dark enough /crowding/ high densities of birds/ boredom or lack of exercise /feed and water troughs too few or too close together/external parasites may cause a chicken to pull out its own feathers, and draw blood. This may attract other birds to peck at the area.


Concluded .....

For further details contact:-
Public Relation & Media Management Cell,
CAU, Imphal. Email: prmm@cau.ac.in