Published online by Cambridge University Press: 27 March 2009
Reproductive performance was assessed in a semi-wild Boran cattle herd living on a grassland ranch in Kenya. Male calves copulated with cows a long time after they were weaned naturally. Up to the age of 16 months they were prevented from mating by adult bulls. Female calves conceived at the average age of 25 months and they had their first calves at about 34 months. Calving interval ranged from 304 to 801 days and averaged 430 days. Calving interval of managed Boran cattle living on the same ranch as the semi-wild herd averaged 494 days with a range of 306–798 days. It is concluded that in herds which are permanently accompanied by adult males artificial weaning and the continuous shift of animals between different cattle groups is not a prerequisite for good reproductive performance.