Data consisting of 445 calving records from Bonsmara breeding females were studied in order to establish relationships between body mass and conception. Significant relationships between body mass at the start of the mating period and percentage conception were established by means of regression (x variate = body mass, y variate = percentage conception) for three of the nine groups tested. Significant relationships between body mass at the end of the mating period and percentage conception were established by means of regression for seven of the nine groups tested. By means of stepwise logistic regressions, the mass at the end of the mating period was identified as the variable accounting for a significant amount of the variation between conception states. Target masses for the start and/ or end of the mating period were suggested for all groups, except for one.

Keywords:  Body mass, Bonsmara, conception, target mass