| dc.description.abstract | Pelvis size, calf birth weight and their ratio are the most important predictors for dystocia. Selection of animals bases on pelvimetry can be used as a tool to prevent or decrease the cases of dystocia. This study looks for relationships between pelvis size and body measurements (body length, shoulder height, heart girth and body condition score (BCS)), reproductive tract score (RTS), gender and age in 4 different beef cattle breeds in the surroundings of Pretoria, South Africa. Pelvimetry is performed together with the body measurements in 230 animals (186 females + 44 males). Breed differences exist for pelvis size as well as body measurements. Mean pelvis area is different per breed, for Brahman it is 160.5 cm2 (SD 30.0), Nguni 138.7 cm2 (SD 20.3), Bonsmara 197.3 cm2 (SD 45.0) and Hereford 217.6 cm2 (SD 55.0). Pelvis size is related to all body measurements, BCS, RTS, age and gender in univariable General Linear Models (GLM). The multivariable GLM for pelvis area has a R2 of 0.893, which means 89.3% of the variation in pelvis area is explained by the explanatory variables. The optimum BCS for the largest pelvis area is BCS3. In case predictions need to be done for precalving pelvis area in heifers, the best moment for prebreeding measurement of pelvis area is when the animal reaches puberty, which corresponds to RTS4 and/or RTS5, when the animal has had its first estrus cycle and a corpus luteum is present. In this data, age of onset of puberty is different per breed, for example the Nguni animals have a later onset of puberty compared to the other breeds. | |
