Animal breeding methods pdf

Flowers, vegetables and fruit-trees may be bred by amateurs and commercial or non-commercial professionals: major crops are usually animal breeding methods pdf provenance of the professionals. There are two approaches or types of artificial selection, or selective breeding.

First is the traditional “breeder’s approach” in which the breeder or experimenter applies “a known amount of selection to a single phenotypic trait” by examining the chosen trait and choosing to breed only those that exhibit higher or “extreme values” of that trait. In this, the breeder does not choose which individuals being tested “survive or reproduce”, as he or she could in the traditional approach. There are also “selection experiments”, which is a third approach and these are conducted in order to determine the “strength of natural selection in the wild”. However, this is more often an observational approach as opposed to an experimental approach.

The deliberate exploitation of selective breeding to produce desired results has become very common in agriculture and experimental biology. Selective breeding can be unintentional, e. For example, in some grains, an increase in seed size may have resulted from certain ploughing practices rather than from the intentional selection of larger seeds. Most likely, there has been an interdependence between natural and artificial factors that have resulted in plant domestication.

The agriculturist selects his corn, letting grow as much as he requires, and tearing out the remainder. The forester leaves those branches which he perceives to be excellent, whilst he cuts away all others. The bees kill those of their kind who only eat, but do not work in their beehive. Arguably, his most important breeding program was with sheep.

Using native stock, he was able to quickly select for large, yet fine-boned sheep, with long, lustrous wool. Bakewell was also the first to breed cattle to be used primarily for beef. As more and more farmers followed his lead, farm animals increased dramatically in size and quality. However, after his death, the Dishley Longhorn was replaced with short-horn versions. Slow though the process of selection may be, if feeble man can do much by his powers of artificial selection, I can see no limit to the amount of change, to the beauty and infinite complexity of the co-adaptations between all organic beings, one with another and with their physical conditions of life, which may be effected in the long course of time by nature’s power of selection.