STUDIES ON THE CARRY-OVER OF POLYCHLORINA TED DIBENZODIOXINES AND DIBENZOFURANINES FROM FEEDSTUFFS IN THE MILK OF COWS

The carry over rate of polychlorinated dibenzodioxines (PCDD) and dibe nzofuranines (PCDF) from feedstuffs in the milk of cows, from feedstuf fs to milk, were studied in four first calving German Simmental cows. The carry over rates and carry over factor were estimated in this stud y over 6 to 19 weeks. During weeks 13 and 14 the means of excretion we re observed. The rate of excretion did not reach a plateau. The intake of PCDD/PCDF during the first 19 weeks varied between 4 and 70 ng per day. The mean carry over effect was 14.4% and the carry over factor w as 3.7. The results after 20 weeks indicated that PCDD/PCDF can be mob ilised in animals with a positive energy balance. No significant relat ionship between PCCD/PCDF concentration in milk and that in tissue fat and blood plasma was detected.