Al zaeim Al azhari University-Khartoum North, 13311-Sudan.
The reproductive and productive performance of exotic breeds in tropical countries is different from what they usually achieve in their original home-land. This is due to the harsh environmental conditions and different climatic conditions beside the rather poor managemental systems. The Holstein-Friesian (HF) cattle can be bred and maintained in tropical environments, although performing less well than Friesians maintained in temperate climates. The observed performance of Holstein-Friesian (HF) under Sudan conditions is commendable. The means for age at first calving, calving interval, service period, number of services per conception, lactation milk yield, daily milk yield, lactation length and dry period are 29.8 months, 433.1 days, 167.8 days, 2.3, 4605.5 litres, 15.1 litres, 322.1 days and 90.0 days, respectively.
