animal breeding Breeding

Breeding objectives can be discussed in terms of changing the genetic makeup of a population of animals, where population is defined as a recognized breed. Choice of breeding goals and design of an effective breeding program is usually not an easy task. Complicating the implementation of a breeding program is the number of generations needed to reach the initial goals. Ultimately, breeding goals are dictated by market demand; however, it is not easy to predict what consumers will want several years in advance. Sometimes the marketplace demands a different product than was defined as desirable in the original breeding objective. When this happens, breeders have to adjust their program, which results in less-efficient selection than if the new breeding goal had been used from the beginning. For example, consumers want leaner beef that is tender. Thus, ranchers have changed their cattle-breeding programs to meet this new demand. These trends have gradually changed over the last few decades; for example, Angus cattle are particularly noted for the quality of beef produced. The use of ultrasound is now widespread in determining the fat and lean content of live animals, which will hasten the changing of carcass quality to meet consumer demands.

Additional complications arise from simultaneously trying to improve multiple traits and the difficulty of determining what part of the variation for each trait is under genetic control. In addition, some traits are genetically correlated, and this correlation may be positive or negative; that is, the traits may be complementary or antagonistic. Breeding methods depend on heritability and genetic correlations for desirable traits.