Objective, Importance and Limitations of Animal Breeding.
Objectives of animal breeding:
- The improved growth rate.
- Increased production of milk, meat, egg, wool, etc.
- Superior quality of milk, meat, eggs, wool, etc.
- Improved resistance to various diseases.
- Increased productive life.
- Increased or, at least, acceptable reproduction rate.
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When breeding is between animals of the same breed for 4-6 generations, it is called inbreeding. Inbreeding can be explained by taking an example of cows and bulls. Superior cows and superior bulls of the same breed are identified and mated.
The progeny obtained from such mating are evaluated and superior males and females are identified for further mating. A superior female, in the case of cattle, is the cow that produces more milk per lactation.
On the other hand, a superior male is that bull, which gives rise to superior progeny as compared to those of other males. Inbreeding increases homozygosity.
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Thus inbreeding is necessary if we want to develop a pureline in any animal. Inbreeding exposes harmful recessive genes that are eliminated by selection. It also helps in accumulation of superior genes and elimination of less desirable genes.
But continued inbreeding reduces fertility and even productivity. This is called inbreeding depression. In this condition, the selected animals of the breeding population should be mated with superior animals of the same breed but unrelated to the breeding population. This often helps in restoring fertility and yield.