Studies on reproduction in prolific ewes

Abstract

SUMMARYA radiographic study was made of the skeletons of 216 Suffolk x (Finnish Landrace x Polled Dorset Horn) sheep foetuses of known gestational age within the range 50–145 days. They comprised 10 singles, 42 twins, 105 triplets, 44 quadruplets and 15 quintuplets.The ages at which the primary and secondary centres of ossification first appeared are presented together with a description of the normal pattern of skeletal development. Attention is drawn to the variations which are found from one foetus to another. The main anatomical features of ovine foetal bone development are illustrated by line drawings and charts.By anatomical grouping the number of ossification centres was reduced to 80, including 40 primary and 40 secondary centres. Scores were obtained for each foetus by taking the numbers of primary and secondary centres that were present as percentages of the possible totals. The primary score was linearly related to foetal age up to about 100 days, and the secondary score was linearly related to foetal age beyond about 100 days. The relationships to foetal weight were similar but less close.