(Traits that can be observed directly, such as size, colour, shape, and so forth, make up an organism’s phenotype.) These genes are known as alleles. Two or more genes may be associated with a specific locus and therefore with a specific trait. Each gene, which is the basic unit of heredity, occupies a specific location, or locus, on a chromosome. Genetic variation is necessary in order to make progress in breeding successive generations. Thus, environmental factors must be considered and controlled in selecting breeding stock. For example, only about 30 percent of the variation in milk production in dairy cattle can be attributed to genetic effects the remainder of the variation is due to environmental effects. For most traits measured in domestic animals, the environment has a larger impact on variation than do genetic differences. Such variations in performance because of the environment are not transmitted to the next generation. Differences in the animals’ environment, such as amount of feed, care, and even the weather, may have an impact on their growth, reproduction, and productivity. For some traits there is an interaction of genetics and the environment. Breeding progress requires understanding the two sources of variation: genetics and environment. Selective breeding utilizes the natural variations in traits that exist among members of any population. Purebred associations provide other services that are useful to their members to enhance their businesses. The essential difference between purebred and nonpurebred animals is that the genealogy of purebred animals has been carefully recorded, usually in a herd book, or studbook, kept by some sanctioning association. Typically, certain animals within a breed are designated as purebred. In animal breeding, a population is a group of interbreeding individuals-i.e., a breed or strain within a breed that is different in some aspects from other breeds or strains. For these reasons he is generally recognized as the first scientific breeder. He was also the first to systematically let his animals for stud. It is thought that he made wide outcrosses of diverse breeds, and then practiced inbreeding with the intent of fixing desirable characteristics in the crossbred animals. Although he did not write about his methods, it is recorded that he traveled extensively by horseback and collected sheep and cattle that he considered useful. His work was based on the traditional method of visual appraisal of the animals that he selected. Breeding and variationĮnglish agriculturist Robert Bakewell was a very successful breeder of commercial livestock in the 18th century. The fundamental biological principles underlying animal breeding are discussed in the articles heredity and animal reproductive system. This article discusses the basic principles of how populations of animals can be changed by application of these principles, and a brief discussion of molecular genetics, immunogenetics, and newer reproductive technologies is included. These include genetics, statistics, reproductive physiology, computer science, and molecular genetics. Selective breeding involves using knowledge from several branches of science. Humanity has been modifying domesticated animals to better suit human needs for centuries. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!Īnimal breeding, controlled propagation of domestic animals in order to improve desirable qualities.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives.
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