Question

Explain how to overcome inbreeding depression in cattle.
(a) List three advantages of inbreeding in cattle.
(b) Name an improved breed of cattle.

Answer 1

Hint: Inbreeding depression is the reduced biological fitness in a given population as a result of inbreeding or breeding of related individuals. This is related to a complication that results in a decrease in fertility and also the productivity of an animal.

Complete Answer:
By the application of outbreeding, inbreeding in cattle can be overcome in which mating is done between individuals of different breeds or individuals of the same breed without having a common ancestor. Outbreeding includes out-crossing, cross-breeding, and interspecific hybridization. This will restore fertility and yield.

1) Advantages of Inbreeding in Cattle:
(i) Inbreeding in cattle helps in evolving a pure line in any animal.
(ii) It exposes harmful recessive genes that are eliminated by selection.
(iii) Inbreeding in cattle helps in the accumulation of superior genes.

2) An Improved variety or breed of Cattle is Hissardale – a new breed of sheep developed by crossing Bikaneri ewes and Merino rams.

Additional Information:
- The first scientists who demonstrate the effects of inbreeding depression were Charles Darwin. He demonstrated these effects through the numerous experiments he did on plants.
- Some physical and health defects shown by first-generation inbred individuals are: high genetic disorders, fluctuating facial asymmetry, decreased birth rate, high infant and child mortality rate,etc.

Note:
- In a given population Inbreeding, depression is the reduced biological fitness that was the result of inbreeding or breeding of related individuals.
- Lower degrees of inbreeding depression is exhibited by hermaphroditic species than the outcrossing species, as repeated generations of selfing purges deleterious alleles from populations.
- For example, unlike its hermaphroditic relative C. elegans, which experiences outbreeding depression, the outcrossing nematode (roundworm) Caenorhabditis remanei has been demonstrated to suffer severely from inbreeding depression.