A group of animals related by descent and similar in most characters like appearance, features, size, configuration, etc., are said to belong to one breed.

The objectives of animal breeding are as follows:

(a) Animal breeding helps to develop pure lines of cattle by inbreeding. When breeding is between animals of the same breed it is called inbreeding, while crosses between different breeds are called out-breeding.

(b) Sometimes continued inbreeding, usually reduces fertility and even productivity. This is called inbreeding depression. Here, out-crossing helps to overcome the problem of inbreeding depression. Out-crossing is the practice of mating of animals within the same breed, but having no common ancestors on either side of their pedigree up to 4–6 generations. The offspring of such a mating is known as an out-cross.

(c) Outbreeding helps to combine the good qualities of two different breeds.

(d) Outbreeding also helps to combine the desirable characters of two different species by interspecific hybridization.