Document Type

Thesis - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)

Department / School

Animal Science


A study was conducted to develop a reliable method to measure presence and quantity of the toxic factor in ponderosa pine (Pinus ponderosa) needles that interferes with normal maintenance of pregnancy in cattle. Special emphasis was given to biological assay sensitivity during embryo implantation and gestation in laboratory animals. The detrimental component was found to be present in both aqueous and acetone fractions prepared from ponderosa pine needles. There was a reduction in average rat litter size from bred rats fed either the aqueous or acetone pine needle extracts throughout pregnancy. Rats fed pine needle extracts from the winter pine needles delivered smaller litters at term than did those fed summer and fall pine needle extracts and the unidentified detrimental component in winter pine needles was more toxic to both dam and fetus. Reduction in viable embryos was observed 5 to 7 days post coitum from mice fed aqueous or acetone pine needle extracts from any of six collection dates. Adrenal weight obtained during the implantation study reflected a time x treatment x age interaction but failed to provide definite conclusions abo·.t ponderosa pine needle toxicity. Gestation study verified results from the implementation experiment as very few mice fed pine needle extracts delivered normal litter. Mice receiving the concentrated aqueous extract suffered diarrhea and inadequate feed intake. It appeared evident that a biological assay at implantation could be used to estimate injury from feeding ponderosa pine needle extracts to bred laboratory animals throughout gestation.

Both dried needles and branches collected throughout the year were analyzed for moisture, ash, crude protein, ether extract, acid-detergent fiber, acid-detergent lignin and in vitro dry matter digestibility. In general, chemical components and in vitro dry matter digestibility changed very little on a month to month basis but low protein content and low digestibility would hinder long term maintenance of an animal on ponderosa pine needles and branches. The use of biological assay in early gestation should serve as a useful screening tool for eventual isolation of the “active ponderosa pine needle abortive factor.”

Library of Congress Subject Headings

Cattle -- Diseases.
Ponderosa pine.
Abortion in animals.

Number of Pages



South Dakota State University