Differentiate between inbreeding and outbreeding in cattle. State one advantage and one disadvantage for each one of them. (3)
Mating of more closely related individuals Breeding of the unrelated animals
within the same breed for 4-6 generations. which may be between individuals of
the same breed but having no
common ancestors for 4-6
1. It is used to evolve a pure line in any animal.
2. Inbreeding exposes harmful recessive genes that are eliminated by selection.
3. It also helps in accumulation of superior genes and eliminatiom of less desirable genes.
Disadvantage: Continued inbreeding causes inbreeding depression that reduces fertility and even productivity.
1. A single outcross helps to overcome inbreeding depression, i.e., fertility and yield in animals.
2. New animal breeds can be developed by cross-breeding, e.g., Hisardale is a new breed of sheep developed in Punjab by crossing Bikaneri ewes and Marino rams.
3. Outcrossing is the best method for animals that are below average in productivity and growth rate.
1. Genes required for adaptation to particular environment are lost or suppressed.
2. In polygynous species advantage of having extra-closely related offspring is lost and parental genes will be less expressed in the next generation. (3)