Genetic improvement of the dairy cattle in the tropical countries: A review

The principles of genetic improvement included the use of crossbreeding. An alternative method is the genetic improvement of the indigenous cattle by selection.
The low reproductive performance and high calf mortality in the indigenous cattle caused a reduction in the selection intensity. Moreover, the generation interval is long in cattle because of the late sexual maturity and the long calving intervals. The most important problem is the absence of a milk recording system in many temperate countries. In such a case, the approach to improving the cattle through selection is limited and we will need to start with a single nucleus.
Two types of selection can be adopted; without progeny testing which means the selection of bulls on pedigree information only and with progeny testing to identify the elite bulls according to the performance of their daughters.