C-10-3

DETERMINATION AND QUANTIFICATION OF PTAQUILOSIDE INMILK FROM COWS FED WITH BRACKEN (PTERIDIUM AQUILINUM). A POSSIBLETHREAT TO SECONDARY BRACKEN CONSUMERS, CALVES AND HUMANS.

Uvidelio F.Castillo, Miguel E.Alonso-Amelot, Barry L.Smith1and Denis R Lauren2.
Universidad de Los Andes, Facultad de Ciencias, Departamento de Química,Grupo de Química Ecológica, Mérida 5101, Venezuela.
1New Zealand Pastoral Agricultural Research Institute Ltd,Ruakura Research Centre, Hamilton, New Zealand.
2The Horticulture and Food Research Institute of New ZealandLtd, Ruakura Research Centre, Hamilton, New Zealand.


Ptaquiloside (ptaq), a major carcinogen P.aquilinum carcinogen,has been found in milk from cows fed bracken in Venezuela. Cows were given6 kg/animal/day of fresh cut bracken fronds whose ptaq content was determinein parallel so as to able to know ptaq consumption. Ptaquiloside fisrtappeared in milk 36 h after start of bracken feeding and continued to beexcreted for 62 h after the bracken diet ceased. Then, it decreased graduallyand disappeared from milk, not before 86 h of the last intake, but up to110 h if the ptaq dosege was high (10.0 mg/animal/day). The average amountof total ptaq excreted [ptaq]e in milk =8.60+/-1.16% of the total ptaqingested [ptaq]i. Although the ratio [ptaq]e/[ptaq]i remained relativelyconstant at various ptaq dosages, [ptaq]e was linearly dose dependent inthe 2.4 to 10.00 mg/animal/day range of ptaq given to the test animals.In a two pulse feeding sequence with a 48h interlude when bracken feedingwas suspended, a binomial ptaq excretion curve was obtiened. The toxicand carcinogenic effects of bracken on grazing animals are well recognized.The health implications to milk consumers such as calves and humans incertain circumstances must now be seriously considered.