The physical relationships of the abdominal organs in the pregnant ewe

Abstract

SUMMARY Five non-pregnant ewes and seventeen ewes at various stages of pregnancy were fed on a medium quality hay for several weeks before being slaughtered and frozen. Each ewe was sawn into 5 cm cross-sections. The sections were photographed. The uterus was extracted from the sections and its volume measured. Volumes of reticulo-rumen contents, intestinal contents and abdominal fat were estimated from the photographs. Models of the uterus and rumen were constructed and examples of these and of the photographs are shown. The volume of the uterus increased steadily as pregnancy progressed, but rumen volume was not reciprocally depressed until the last 5 weeks of pregnancy. Volume of digesta was inversely related to volume of incompressible abdominal content (uterus and fat). Abdominal fat was a particularly important factor in the depression of rumen capacity in pregnancy when there was great competition for space in the abdomen.