Effects of extracts of toxic fescue given orally to rats.

Fresh fescue (Festuca arundinacea) was obtained from farms where toxicity was encountered in cattle grazing the fescue. The fescue was dried in a forced draft oven at 60 degrees C and then ground. The dry ground fescue was extracted with ether and then re-extracted with either 1% sodium bicarbonate (NaHCO3), sodium hydroxide or hydrochloric acid. The residual ether was evaporated and the residue resuspended in ethyl alcohol diluted with water 1% (control) and 1 mL of the above extracts of fescue were given daily to rats, via stomach tube, beginning the seventh day after breeding. Two of the seven rats given the 1% NaHCO3 fraction of the extract of fescue gave birth to live young. One of these litters contained only five pups, with one being stillborn. Three of the seven rats aborted, one gave birth to seven stillborn pups and one female died during birth. All females fed the 1% NaHCO3 and the other extracts of the fescue gave birth to normal litters. Rats fed the ether extract which was re-extracted with 1% NaHCO3, acidified and re-extracted with ether, dried and resuspended in 1% NaHCO3 produced similar reproductive problems as those rats given the ether extract of fescue which was re-extracted only once with 1% NaHCO3. Therefore, it appears that the toxic entity(s) of fescue can be extracted and that infertility/abortion/still-birth ratio of rats may be used as a bioassay.