Natural occurrences of ochratoxicosis in poultry.

Five independent episodes of ochratoxicosis in about 970,000 turkeys, two episodes in about 70,000 laying hens, and two episodes in about 12,000,000 broiler chickens were investigated. Ochratoxin A concentrations in suspect feed and ingredients ranged from less than .2 to 16 ppm. Feed samples tested for T-2 toxin, F-2 toxin, heavy metals, and polychlorinated biphenyls were negative. Minor amounts of aflatoxin (less than 60 ppb) were found in suspect feed from two episodes. The main symptoms in turkeys were mortality (up to 59%), nephrotoxicity (pale, swollen kidneys that became tan colored in the sequel to acute toxicity), decreased feed consumption (as little as 20% of the normal feed intake) prior to death, and secondary air sacculitis. Histopathology revealed edema and necrosis of the proximal tubules of the kidneys and no changes in the liver or other organs. Suspect feed containing 2 ppm ochratoxin A increased uric acid levels in serum when fed to poults in the laboratory. The episodes in laying hens were characterized by reduced egg production, poor egg shell quality, and nephropathy. The episodes in broiler chickens were characterized by poor growth rate, poor feed conversion efficiency, poor pigmentation, nephropathy, and increased incidence of air sacculitis. Obtaining feed and ingredients free of ochratoxin, cleaning the feed and ingredient handling equipment, and adding antifungal agents to the feed proved beneficial. Eight of the 9 episodes were traced to the corn supply and the ninth episode was traced to corn gluten meal that became contaminated during storage after manufacture. Evidence was obtained that the ochratoxin was unstable and declined in concentration during storage. Aqueous acetone was a better solvent for extracting ochratoxin than was the recommended phosphoric acid: chloroform. The ochratoxin extracted from high potency samples consisted of ochratoxins A, B, and C in ratios of about 90:8:2.