SYSTEMS OF BREEDING- DIFFERENT METHODS
Animal breeding is performed to domestic animals in order to improve desirable qualities and to better suit human needs.
Generally, two ways of matings are prevalent:
Natural mating: It refers to mating of animals by natural means.
Artificial insemination (AI): It is the technique in which semen with living sperm is collected from the male and introduced into female reproductive organ. So, mating is done through artificial means.
System of breeding
Basically, there are two systems of breeding:
- Inbreeding
- Breeding or matting of the related animals is known as inbreeding.
- Inbreeding is often described as “narrowing the genetic base” because the mating of related animals produces offspring that have more genes in common.
- Inbreeding is used to concentrate desirable traits.
- Inbreeding is generally detrimental in domestic animals. Increased inbreeding is accompanied by reduced fertility, slower growth rates, greater susceptibility to disease, and higher mortality rates. Hence, this method of breeding is not practiced for livestock improvement.
- Inbreeding is often practiced to create genetic uniformity of laboratory stocks and to produce stocks for crossing.
- It is of two types:
Close breeding: Here animals are very closely related and can be traced back to more than one common ancestor. Examples: Sire to daughter, Son to dam, Brother to sister.
Line breeding: Mating animals that are more distantly related which can be traced back to one common ancestor. Examples: Cousins Grandparents to grand offspring, Half-brother to half-sister. Line breeding increases genetic purity amongst the animals of progeny generations.
- Out breeding
It is breeding of unrelated animals. The effect of out breeding is opposite of inbreeding because heterozygosity is increased here. It is of two types-
Cross breeding: Crossbreeding involves the mating of animals from two breeds. Normally, breeds are chosen that have complementary traits that will enhance the offsprings’ economic value. Superior traits that results in the crossbred progeny from crossbreeding are called hybrid vigor or heterosis. So, it is done to take advantages of good qualities of two or more breeds. It is mainly used by commercial producers.
Grading up: Grading up is the breeding of animals of two different breeds where the animals of an indigenous breed/genetic group is mated by an improved pure breed for several generations in order to get superior traits of the improved breed.
Grading up is continuous use of purebred sires of the same breed in a grade herd. By fifth generation, the graded animals may reach almost purebred levels.
Frequently Asked Questions (FAQ)
What is the difference between Inbreeding and Cross breeding?
Breeding or matting of the related animals is known as inbreeding while, Crossbreeding involves the mating of animals from two breeds. Inbreeding increase homozygosity whereas, Cross breeding increases heterozygosity.
What should be the level of exotic inheritance?
It should never exceed 62.5% in order to exploit the full genetic potential for a sustainable production.
What is back crossing?
The cross bred female obtained by crossing two breeds are mated to males from one of the two parental breeds.