Short communication: Toxicokinetics of ochratoxin A in dairy ewes and carryover to milk following a single or long-term ingestion of contaminated feed

Ruminal microbes have the capacity to inactivate ochratoxins, rendering ruminants less sensitive to this fungal contaminant found in cereal feeds. However, ochratoxin A has been reported in milk surveys. The objective of this study was to assess the toxicokinetics, excretion, and transmission into milk of ochratoxin A using doses similar to those of naturally occurring field contaminations. Six Lacaune dairy ewes in late lactation were separated into 2 groups that received a single dose of contaminated wheat containing 5 or 30 p,g of ochratoxin A/kg of body weight. After administration, toxicokinetics and excretion were monitored for 48 h. Subsequently, ewes were administered the corresponding toxin dose daily for 24 d followed by a second toxicokinetics and excretion monitoring period for this long-term exposure. The doses used did not affect production or health of ewes. After a single dose, ochratoxin A and its main metabolite, ochratoxin alpha, were found in blood 1 h postexposure. The maximum blood concentrations of ochratoxin A and alpha, respectively, were dose dependent and were observed, on average, 6 and 8 h after exposure. Long-term exposure increased the maximum concentration of ochratoxin A detected in blood, whereas ochratoxin alpha was not affected. In contrast, the time to reach the maximum concentration was reduced to 3 h for both molecules. Ochratoxins, essentially ochratoxin alpha, were mainly excreted in feces. Ochratoxin A and alpha were detected in milk at concentrations that were dose dependent but with a low carryover rate (<0.02%). Chronic administration did not increase the concentration of toxin in milk. Even though ochratoxin A can escape ruminal degradation and traces were found in milk of experimentally exposed ewes, the low carryover of ochratoxin A in milk minimizes the risk to consumers.