E. DOUGHERTY III.
DUCKS are waterfowl and scavengers by nature and are relatively resistant to many common diseases of birds.
The large, modern, commercial duck ranch is a long step from nature, however. Confinement creates such problems as a damp, ammonia-laden atmosphere; rapid spread of some diseases that are almost unknown in wild ducks (paratyphoid, serositis, and fowl cholera); heavy insect populations; and leg weakness.
On the other side of the ledger, confinement rearing (with a controlled water supply) has all but eliminated western duck sickness (botulism), parasitism, and attack from predatory animals, which are scourges of wild ducks.
The duck rancher has to provide an escape for moisture to prevent ammonia burn. To accomplish that he replaces the litter daily or provides wire floors over washable pits on at least part of the building. Other problems, such as botulism, have been solved by the use of pelleted feed and a constant water level.
Flies can be controlled by modern chemicals. They must be checked before use, however, because some of the thiophosphates, which are safe to use in chicken houses, are highly toxic to ducks.
PARATYPHOID, or keel, is an infectious disease of young ducklings (also of turkeys and other birds). It is caused chiefly by a bacterium, Salmonella typhimurium, and to a less extent by other species of salmonellas. Mortality is usually low (less than 10 percent) on Long Island, but poor incubator and brooder management increase the death rate.
The name "keel," which stems from early observations that the ducks suddenly keel over when dying, is misleading. Often the ducklings become dehydrated and emaciated and die slowly. They may gasp for air or tremble, as though chilled.
The common lesions are small, white spots on the liver, cheesy plugs in the blind gut, and a thickening of the wall of the large gut.
The best preventive measure we know of is to fumigate the eggs during early incubation and the hatching unit between hatches. Potassium permanganate and formalin are recommended.
Potassium permanganate crystals should be used at the rate of one-half ounce (weighed) and 1 ounce of formalin (measured) to every 80 cubic feet of incubator or hatcher space. The potassium permanganate crystals are placed in an earthenware vessel with a capacity of 1 pint for each ounce of formalin required. The vessel is placed on the floor of the machine and the formalin poured over the crystals. The doors and vents should be closed for 15 minutes. This procedure should be followed in the incubator 3 to 5 days after each new lot of eggs is set, and in the hatcher between hatches after the hatcher has been cleaned. Fumigation should not be done while the ducklings are hatching. The farmer should not inhale the fumes and should handle the poisonous formalin carefully.
Treatment consists of rigid culling and sulfonamide medication in the feed or drinking water. NF-180 can be used in the feed at the rate of 2 pounds to the ton for a week to 10 days. Sulfamethazine can be used in the drinking water at the rate of 1 ounce (2 tablespoons) to the gallon of drinking water for 2 days; the treatment can be repeated after 4 days, if necessary.
The ducks should be kept on clean bedding, because S. typhimurium may be found in the feces of affected ducks and can be transmitted by ingestion of infected material. The bacteria can live 28 weeks in feces. Thorough cleaning and disinfecting of the brooder house after removal of an infected flock therefore is important.
VIRUS HEPATITIS baby duck disease is a highly fatal virus disease of young ducklings. It runs rapidly through a flock and kills many. The dead and dying birds are found with their heads thrown back.
The disease was first discovered in white pekin ducks on Long Island in January 1950. The virus since has been isolated from wild ducks (mallards) on Long Island and from domesticated ducks in Massachusetts, western New York, Illinois, and England.
Losses up to 90 percent are common and occur within 2 days of the first death. The biggest ducklings in a flock die first and without warning. Individuals are dead 30 minutes after showing the first signs. They lie on their sides with their heads thrown back. The feet may paddle as though they were swimming, and the beak often is purple. Lesions consist of small hemorrhages on the liver and mottling of the spleen and kidneys.
Treatment with serum from ducks that have recovered from the disease has been used successfully. A serum bank sufficient to treat many thousands of ducklings is maintained on Long Island. The bank consists of about 2 million milliliters of blood serum collected at slaughter from ducks that had the disease and recovered. The serum is separated from the clots and treated with a preservative. The serum is then stored under refrigeration and issued, as needed, to the duck farm.
Geese, muscovies, chickens, turkeys, and game birds reared in contact with infected ducks have failed to show any evidence of the disease.
ASPERGILLOSIS, a respiratory disease of young ducklings, is caused by the fungus Aspergillus fumigates. It is also known as brooder pneumonia and gaps. Ducklings less than 2 weeks old are most susceptible, but the fungus has been found growing in the air sacs of ducks of all ages, including breeders.
Affected birds gasp for air and the head and neck are extended. Many become weak and actually may die of thirst.
Cheesy nodules, from pinpoint size to one-eighth inch across, occur in the lungs and air sacs. The filamentous type of growth, similar to that seen on moldy bread, may be present in the air sacs of older ducks.
Moldy litter, the most common cause of an outbreak, should never be used for young ducklings. Moldy feed should be avoided. Every effort should be made to keep the area around the water fountains dry through the use of wire platforms and drains.
Treatment of individual birds is unsatisfactory. The litter in affected pens should be removed or covered with fresh litter.
INFECTIOUS SEROSITIS anatipestifer infection or "new duck disease" is so widespread as to be the most important disease problem of the duck industry. It is a bacterial disease caused by Moraxella anatipestifer.
The symptoms are coughing, staggering, and loss of equilibrium. Frequently the ducks lie on their sides or backs and paddle their feet. Death often is due to water starvation, rather than to the primary infection. Loose green and white droppings are common in a pen of affected ducks. Losses up to 75 percent have been recorded.
The characteristic lesion consists of a cream-colored, gelatinous membrane, one-sixteenth inch or more thick, over the heart and liver. The air sacs may contain a yellow, cheesy exudate. The liver and spleen are enlarged. Hemorrhages may be present beneath the capsule of the liver.
Terramycin suspension in oil gives good control for about 5 days. The treatment consists of injecting the drug under the skin of the neck at the rate of 12.5 milligrams per pound of body weight. Treatment may have to be repeated.
Sulfa drugs have been widely used, with varying results. One and one-half pounds of sulfaquinoxaline per ton of feed is the recommended level. The ducks should be starved for 4 to 6 hours and the medicated feed given for the remainder of a 24-hour period. This treatment may be repeated if necessary.