Belmont red and Brahman cows (n = 50) were allocated to one of two groups to determine if β-carotene supplementation could reduce the incidence of mastitis and consequently improve calf productivity from birth to weaning. Both groups received a molasses-based supplement ad libitum; the treatment group supplement was fortified with ROVIMIX^® β-carotene and ROVIMIX^® E50 whereas the control group were provided access to the molasses supplement only. Blood samples were collected from cows pre and post calving and from calves when 84 ± 0.4 days old to measure plasma β-carotene concentration (PCC). Milk samples were collected 7 and 84 days post calving and at weaning and analysed for somatic cell count (SCC) and composition. Supplementation had no significant (P > 0.05) effect on SCC, calf PCC, calf LW gain and LW at weaning. Supplemented cows had significantly (P < 0.05) higher PCC compared with unsupplemented cows (4.9 ± 0.36 v. 3.9 ± 0.24 mg/L, respectively) at weaning. Cows commenced the study in an above-average condition, and combined with unseasonal green forage it is concluded that β-carotene supplementation has no effect on mastitis or calf weaning weight.