Question

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

Answer 1

Hint: The decreased biological fitness in a given population due to inbreeding or breeding of related individuals is inbreeding depression. It is related to a complication that leads to a decrease in fertility and thus, affects the productivity of animals.

Complete answer: Charles Darwin was the first researcher to explain the symptoms of inbreeding depression. Through various experiments performed on plants, he showed these results. Some physical and health defects exhibited by inbred individuals of the first generation are high genetic abnormalities, fluctuating in facial asymmetry, reduced birth rate, the high mortality rate in infants and children.
(a) Breeding in cattle involves mating being conducted between individuals of different breeds or individuals of the same breed without having a common ancestor that can be resolved by the use of outbreeding. Outbreeding includes hybridization of outcrossing, cross-breeding and cross-breeding. It restores yield and fertility.
(b) The three advantages of inbreeding in cattle are;
i. Breeding in cattle helps to create a pure line in any species.
ii. It shows unwanted recessive genes that are killed by selection.
iii. Breeding of cattle helps to gain superior genes.
(c) Hissardale, a new breed of sheep developed by the blending of Bikaneri ewes and Merino rams, is an improved species or breed of cattle.

Note: Depression reduces biological fitness in a given population. As multiple generations of self-purging populations purge deleterious alleles, the hermaphroditic species experiences lower levels of inbreeding depression than the outcrossing species as compared to the hermaphrodite equivalent. For example; the outcrossing nematode (roundworm) Caenorhabditis remanei, which is suffering from outbreeding depression has been shown to suffer significantly from inbreeding depression as well.