Inactivation of ochratoxin in ruminal fluid with variation of pH-value and fermentation parameters in an in vitro system

Ochratoxin A which is degraded to ochratoxin a in the rumen may have negative effects on kidney function. However, the toxicity of ochratoxin a is significantly lower than of ochratoxin A. The objective of this study was to examine the effect of different ruminal parameters such as pH and fermentation on the inactivation of ochratoxin A. These studies were performed under in-vitro conditions by using the 'Hohenheimer gas test'. Incubation was carried out over a period of 48 h by incubating pure ochratoxin A with a mixture of ruminal fluid and a culture medium. The concentration of ochratoxin A was 200 mu g/l of ruminal fluid. Ochratoxine was determined by high performance liquid chromatography (HPLC)-fluorescence detection. The recovery rates for ochratoxin A and ochratoxin alpha were 70 +/- 6 and 53 +/- 4%, respectively. The ruminal degration rate of these toxins was affected by the relation of roughage and concentrate in the complete diet, i.e. in diets comprising of 40% roughage and 60% of concentrate the degradation rate was higher than in diets consisting of 100% concentrate. The relation of roughage to concentrate in the complete diets (n = 4) had a significant effect on the half-life of the toxin that were measured. In this study, a shorter half-life for ochratoxin A was estimated when starch was added to the medium, pH had no significant effect on the degradation rate of ochratoxin A. (C) 1999 Elsevier Science B.V. All rights reserved.