No abstract

Haematological, biochemical and toxicological investigations of blood and urine of normally slaughtered pigs exhibiting different frequency (1-2 O/o, 10-20 % and 5 M 0 ' 1 . ) of changes characterized as "enlarged mottled kidneys"; at the slaughtering meat inspection were carried out to elucidate the nature of nephropathies encountered in Bulgaria. A content of ochratoxin A, higher in the spring than the autumn, was found in the serum and urine samples. The mean contamination levels of ochratoxin A in consumed feeds ranged from 114 k 36 ppb for 1994 to 207 k 65 ppb for 1993.The renal changes were characterized by impairment of proximal tubular function (indicated by an increased urinary excretion of glucose and protein) as well as by decreased specific gravity and increased pH in the urine mainly in pigs with 5 M 0 % frequency of nephropathy. The concentration of urea, creatinine and glucose in the blood was increased, whereas the serum protein and cholesterol were decreased in pigs with 10-20% and 5 0 4 0 % frequency of nephropathy. The mean enzyme levels of gamma-glutamyl transpeptidase and leucine aminopeptidase were significantly increased in the urine. The presence of granular casts and necrotic renal tubular cells were established in the sedlment.

Mycotoxic nephropathy was induced in 18 young pigs by diets contaminated with strains of Aspergillus ochraceus containing ochratoxin A (OTA) and penicillic acid (PA) at levels corresponding to those naturally encountered in animal feeds in Bulgaria. Haematological and biochemical parameters, as well as the morphological and ultrastructural changes in various internal organs, and especially in the kidneys, were examined at different stages of development of the disease. A mottled surface of the kidneys was only seen in pigs exposed to a mouldy diet containing 180 ppb OTA for 3 months, but microscopic lesions, as well as changes in various haematological and biochemical parameters, were observed in all groups exposed to the same mouldy diet containing only 90 or 180 ppb OTA. Histological examination showed two types of change: degenerative changes affecting the epithelial cells of the proximal tubules, which predominated at the initial stage, and proliferative changes in the interstitium, which predominated at the later stage of the disease. Telangiectasis and lymph stasis were also seen, as well as degenerative changes in the capillary endothelium. The characteristic renal lesions were similar to those observed in spontaneous cases of mycotoxic porcine nephropathy in Bulgaria, but they were a little different from the classic Danish porcine nephropathy. The enhanced toxicity of OTA in our study may be due to a synergistic effect between OTA and PA or to some other unknown metabolites produced by the same ochratoxinogenic strains of A. ochraceus.