Answer in short:
 
Farmers aim to develop cattle that produce high milk yield and also survive well in local climatic conditions. Crossbreeding indigenous and exotic breeds helps achieve this goal.
Answer variants:
milk yield
hardy
natural breeding and artificial insemination
hybridisation
a.  
Exotic breeds are known for higher __________ and longer lactation periods.
 
b.
Indigenous breeds are __________ and resistant to many diseases.
 
c.
Name the two methods of crossbreeding used in cattle improvement.