Effect of feeding ponderosa pine needle extracts and their residues to pregnant cattle.

Solvents including ethanol, methylene chloride, acetone, hexane, and hot and cold water were used in separate procedures to extract needles and bark from ponderosa pine (Pinus ponderosa L.) to determine which system was optimal for the extraction of abortifacient compound(s). The extracts and residues therefrom were fed by gavage to pregnant cows beginning at day 250 of gestation. After methylene chloride extraction, the pine needle residue fed by gavage failed to abort 4 cows. Subsequently, 4 cows fed the methylene chloride extractable material, adsorbed on ground hay, but free of methylene chloride, aborted (days 253-260 of gestation) and all 4 cows retained fetal membranes. Only 2 of 6 cows fed the pine needle residue after ethanol extraction aborted (days 260 and 261 of gestation) and both retained their fetal membranes, while the other 4 cows calved normally. Hot and cold water extracts did not cause abortion, whereas the extracted plant residue did. One cow fed the plant residue after acetone extraction calved normally as did 1 of 2 cows fed residue after hexane extraction. One cow fed hexane extract absorbed on ground hay also calved normally. These results demonstrate that abortifacient compound(s) present in pine needles are most efficiently extracted by methylene chloride.