ABSTRACT
The first step in an animal improvement program is to define what kind of animal is best for the purposes of the people in the country concerned. Measurement or appraisal of an animal's merit merely expresses how closely that animal conforms to the ideal. Merit may be defined either phenotypically or genetically. Improvement in animal breeding can follow two different roads. The first road, the traditional one, is to select the best and cull the worst in the hope of improving the whole stock more or less steadily. The second road leads toward a situation in which seedstocks are bred separately from each other but are out-crossed, in one way or another, to produce animals for use. An animal taken from its native country to a land with a distinctly different climate may require many months to adjust its own individual physiology in the new environment. If the animal is mature when imported, it may never complete this adaptation.
