In this experiment, the influence of phosphorus supplementation on growth and reproductive characteristics of beef cows in the semi-arid bushveld of South Africa was studied. The parameters in this study included weight, intercalving period and conception rates of cows, as well as birth weight, weaning weight and weight gain of calves. The experiment consisted of three trials. Trial 1 involved Bonsmara cows with four dietary supplementation groups. These were control, phosphorus supplementation all year round, phosphorus supplementation in the summer months and summer phosphorus supplementation with a winter lick. Trial 2 dealt with Bonsmara cows and included two dietary supplementation groups, namely control and phosphorus supplementation all year round. Trial 3 compared four different breeds (Afrikaner, Simmentaler, Nguni and Bonsmara) and included two dietary supplementation groups, notably a control group and a Kimtrafos 12 P supplementation all year round. Phosphorus supplementation had no significant effect on cow weight in Trial 1 (p > 0.1), but was significant in Trial 2 (p< 0.001) with the supplemented group performing better than the control group. In Trial 3, phosphorus supplementation had a varied effect on cow weight, because it only had an effect for the months of June to November (p< 0.05). Phosphorus supplementation had no significant effect on birth weight in any of the trials. Treatment did however either show a tendency towards significance or was significant for weaning weight and weight gain in Trial 2 (p= 0.0272 and p= 0.0524 respectively) and Trial 3 (p= 0.0587 and p= 0.0464 respectivey), with the treated groups performing better than the control groups. There was no improvement in calving interval or conception rate for phosphorus supplemented cows in any of the trials. / Dissertation (MSc(Agric))--University of Pretoria, 2008. / Animal and Wildlife Sciences / unrestricted