Selective breeding of animal, which would possess the desired characters, is essential to meet the ever increasing demand of food products like eggs, milk and meat. This can be done by cross-breeding animals of two different breeds each having some of the desired characters. We should, in this respect, keep in mind the following points:
1. Lactation period
2. Reproductive period
3. Nutritional requirements
4. Tolerance of climatic conditions
5. Resistance to diseases and yields.