The calving rates, survival and growth of calves of Brahman (344), Bonsmara (454), Simmental (601) and Tuli (276) crossbred cows, and pure Tswana (405), were collected for a 7-year period, 1974–80. Calving and survival rates for calves were 0·90, 0·88, 0·87, 0·87 and 0·82; and 0·94, 0·93, 0·96, 0·94 and 0·93, for Simmental, Tuli, Brahman and Bonsmara crossbreds, and pure Tswana, respectively. These differences were not significant (P<0·05).
Calves produced by Simmental ♂ and Bonsmara ♂ crossbred cows were significantly heavier than those from Brahman ♂ and Tuli ♂ crossbred cows (P<0·01), but not from Tswana-sired calves. At weaning, calves from Simmental-cross cows weighed 214 kg, significantly heavier than those produced by any other cow type (P<0·01). Bonsmara- and Brahman-cross cows produced calves weighing 203 and 198kg respectively at weaning, which were also significantly heavier than the calves of Tswana and Tuli crossbred cows (P<0·01), which weighed 187 and 184 kg respectively.
Productivity estimates combining these three traits, and expressed as weight of calf weaned per cow per year, per kg cow weight and per kg metabolic weight of cow, demonstrate the advantages of three of the crossbred cow types over the pure Tswana. Recommendations for the further development of crossbreeding systems in Botswana are made on the basis of this finding.