Relationship between pelvic and linear body measurements in Dorper ewes

Low lifetime rearing success and high perinatal mortality of lambs have been associated with small pelvic areas in ewes. It would therefore make sense to include pelvic area as a criterium for selecting breeding ewes; however, measuring it in vivo poses some challenges. The aim of this study was to determine pelvic height, width and area and to estimate correlations between these measurements and other external linear body parameters, i.e. body height, shoulder height, chest depth, front quarter width, hindquarter width, rump length and rump slope in Dorper ewes. A total of 332 young Dorper ewes (± 12 months old; 48.0 ± 5.9 kg) were used. The overall mean pelvic area of yearling Dorper ewes was 35.4 ± 4.9 cm2. Registered ewes recorded significantly larger pelvic areas (37.4 ± 4.3 cm2) than commercial ewes (33.9 ± 3.8 cm2). Results also indicate no correlations between pelvic measurements and other body measurements considered in this study, indicating the need to measure the pelvic area of ewes directly. The pelvic meter and techniques used in this study proved to be relatively easy to use in measuring the pelvises of sheep.