A leucocytopenia induced in chickens by dietary ochratoxin A

Ochratoxin A was fed (0, .5, 1.0, 2.0, 4.0, and 8.0 microgram/g) to broiler chickens from day-old to three weeks of age when the birds were bled and total leucocyte and differential counts were performed. Ochratoxin A significantly (P less than .05) reduced leucocyte counts at every dose level of ochratoxin A administered. The leucocytopenia was characterized by an increase in the relative concentration of heterophils and decrease in the relative concentration of lymphocytes. From total leucocyte and differential leucocyte counts the number of circulating cells was calculated for each type of leucocyte. The total number of circulating lymphocytes of blood decreased significantly (P less than .05) at every dose level of ochratoxin A administered, and the number of monocytes decreased at 2.0 microgram/g and above. However, the number of circulating heterophils was not altered. These data demonstrated that ochratoxin A induced a severe leucocytopenia (lympocytopenia primarily and monocytopenia to a lesser extent) and implied that the functioning of the immune system might be altered.