The effect of pelvic area on lambing ease in maiden Dorper ewes

Abstract

This study aimed to assess the pelvic area in maiden Dorper ewes and examine its influence on lambing ease, birth assistance, parturition duration, and the ratio of pelvic area to lamb weight. Pelvic dimensions of the ewes, along with the external body measurements of their newborn lambs, were recorded. The study involved 369 young Dorper ewes, aged 9.31 ± 1.19 months and weighing 52.32 ± 4.25 kg. The average pelvic area measured was 33.45 ± 3.12 cm², calculated using the formula: π * (Pelvic height/2) * (Pelvic width/2). Ewes born as twins had a larger pelvic area compared to those born as single lambs. The average time taken for lambing was 52.22 ± 37.34 minutes, with 67% of the ewes requiring assistance. The ratio of pelvic area to lamb birth weight was 9.69 cm² per kilogram. Significant correlations were found between birth aid scores and various lamb size factors, with correlations ranging from 0.2 to 0.8. The factors most influencing lambing ease were lamb head circumference and ewe birth weight, with an R² value of 0.243.