Ochratoxicosis in the Broiler Chicken , ,

Graded doses of ochratoxin (0, 0.5, 1.0, 2.0, 4.0, and 8.0 μg./g.) incorporated into the feed of broiler chickens from hatching until three weeks of age resulted in a decreased growth rate, enlarged kidney, crop, proventriculus, gizzard, and liver, while the bursa of Fabricius was regressed and the sizes of the heart, spleen, and pancreas were unaffected. The most sensitive indicators of ochratoxicosis were reduced growth rate and enlarged kidneys which occurred at doses as small as 1.0 μg./g. The determination of LD50 values indicated that three-week old chickens (3.60 ± 0:57 mg./kg.) were more resistant than day old chickens (2.14 ± 0.37 mg./kg.). Observation of birds dying from acute ochratoxicosis revealed a progression of symptoms from listlessness, huddling, diarrhea, tremors and other nerual abnormalities, prostration, to death which occurred 22 to 25 hours after a single oral dose of 16 mg./kg. was given. Necropsy of these birds revealed food in the crop, proventriculus and gizzard. The lower intestine was empty of its normal contents. Petechiae of the papillae of proventriculus, slight gizzard erosions, and paleness of the liver, pancreas, and especially the kidney were the only gross pathological lesions noted. On the basis of LD50 dose and minimal growth inhibitory concentration, ochratoxin appears to be the most potent mycotoxin studied in chickens.