家禽 其他霉菌毒素中毒

Ochratoxins are quite toxic to poultry, as nephrotoxins produced chiefly by Penicillium viridicatum and Aspergillus ochraceus in grains and feed. Ochratoxicosis primarily causes renal disease but also affects the liver, immune system, and bone marrow.

Ochratoxicosis causes the following:

• decreased weight gain and poor feed conversion

• decreased spontaneous activity

• hypothermia and huddling

• diarrhea, rapid weight loss, and death

• decreases in carcass yield, egg production, egg quality, fertility, and hatchability

Toxic ergot alkaloids are produced by Claviceps spp, which grow on cereal grains. Rye is especially affected, but wheat and other cereal grains are also.

The mycotoxins form in the sclerotium, a visible, hard, dark mass of mycelium that displaces the grain tissue. Within the sclerotium are the ergot alkaloids, which target multiple body systems:

• the nervous system, causing convulsive and sensory neurologic disorders

• the vascular system, causing vasoconstriction and gangrene of the extremities

• the endocrine system, including neuroendocrine control of the anterior pituitary gland

In chicks, the toes become discolored due to vasoconstriction and ischemia. In older birds, vasoconstriction affects the comb, wattles, face, and eyelids, which become atrophied and disfigured. Vesicles and ulcers develop on the shanks of the legs and on the tops and sides of the toes.

Decreased feed consumption and egg production occur.

Citrinin is produced by Penicillium and Aspergillus and is a natural contaminant of corn, rice, and other cereal grains.

Citrinin causes diuresis, watery feces, and decreases in weight gain. At necropsy, mild lesions can be found in the kidney.

Oosporein causes gout and death in poultry. Oosporein is produced by Chaetomium spp and occurs in feed and grain, including peanuts, rice, and corn.

Both visceral and articular gout are related to impaired renal function and elevated plasma concentrations of uric acid. Chickens are more sensitive to oosporein than turkeys.

Water consumption increases during intoxication, and feces become unformed and fluid.

Cyclopiazonic acid is a metabolite of Aspergillus flavus, which is the predominant producer of aflatoxin in feeds and grains.

In chickens, cyclopiazonic acid causes impaired feed conversion, decreased weight gain, and death, with lesions forming in the proventriculus, gizzard, liver, and spleen. The proventriculus is dilated, and the mucosa is thickened and variably ulcerated.

In laying hens, cyclopiazonic acid affects eggshell quality and leads to higher cracks in eggs.