Animal husbandry is the scientific breeding and management of domesticated livestock to achieve qualities desired to meet various nutritional, labor, recreational, and other derivative needs, such as leather, fur, and pharmaceutical sources. Early humans recognized traits in certain animals which they bred to create offspring with those characteristics. Animals which did not meet expectations were culled from breeding stock and sometimes castrated or slaughtered. These primitive animal husbandry methods were based on observation and experience, not genetics. Breeders knew that certain reproductive crosses tended to produce vigorous animals, but they did not understand the scientific principles of animal husbandry until twentieth century geneticists began to comprehend the potential roles of genes for agricultural applications.
Animal husbandry became professionalized in the twentieth century as scientists theorized and determined ways to manipulate livestock's genes regarding such factors as growth and biochemical activity. Jay L. Lush (1896-1982), an Iowa State University animal husbandry professor, is considered the father of modern animal breeding and genetics. His research resulted in an international breeding study center being established at Iowa State that continues to influence animal husbandry world-wide.
Livestock breeders who accept genetic principles carefully choose breeding stock to develop lines that consistently produce animals with similar characteristics. Genetics technology enables breeders to cultivate meatier, tastier, larger, speedier, or sturdier animals. Aware of plant breeding experiments, animal husbandry researchers recognize the value of true-line breeding to reinforce certain ideal genetic traits such as strength and vigor associated with specific breeds. Genetically similar animals usually produce offspring which have the same characteristics.
Inbreeding is a genetic strategy to produce superior specimens by mating animals closely related in an attempt to concentrate desirable genetic material in offspring. Recessive inferior genes that are not detectable in the parents, however, may become visible in the offspring which might be smaller or express some other weakness and undesirable traits. Outcrossing involves breeding unrelated animals of the same breed in an attempt to develop their outstanding traits in offspring. Crossbreeding, or the mating of animals from two breeds of the same species, is another method to achieve better quality livestock who obtain higher prices at market. Hybrids such as the geep, a cross between a sheep and a goat, represent desirable traits of each species.
At livestock shows, judges rate animals according to the size, conformation, and other categories, validating certain genetic breeding programs. Winning animals become more desirable as breeding stock. Improved technology enable sperm to be frozen and distributed across a broader geographic area for artificial insemination. Eggs are often harvested from superior female specimens, and embryos are implanted in surrogates. Thus, genetically superior livestock can produce more offspring than naturally possible during a breeding season. Scientists also achieved the cryopreserving of many livestock species' embryos to enable efficient production to meet consumer demands and generate profits.
Sophisticated genetics techniques have advanced animal husbandry. Livestock breeders can custom design animals to meet their demands. They can select the gender of animals and characteristics such as leanness that may earn more money at markets. Scientists use immunogenetics to produce disease and parasite resistant animals by identifying, transferring, and recombining desirable genes. Genetically modified, or transgenic, animals are created by inserting a genetic construct, which is a DNA sequence with a desired gene, into a fertilized egg. Transgenic livestock are useful for producing proteins, organs, and genetic material appropriated for human pharmaceuticals and medical procedures such as cell-based therapy for specific diseases. The genetic engineering of livestock for human medical applications is known as pharming. Entire herds of transgenic animals can be created to meet certain nutritional and medical human needs.
The development of cloning livestock by using genetic material to make identical copies enabled the potential to create large numbers of superior specimens to meet consumer demand. Biotechnology applications to animal husbandry have been patented and commercialized, and major corporations invest in animal bioengineering. Infigen was the first international commercial livestock cloning corporation.
Animal husbandry professionals also rely on genetics to save money. Geneticists use DNA markers for mapping the genetic potential of calves so that breeders can determine whether those animals will mature into viable breeding stock. Gene-based tests were developed at the National Animal Disease Center in Ames, Iowa, to detect the presence of Johne's disease which costs dairy cattle producers approximately $1.5 billion annually. Researchers use a cloned gene of the disease-causing organism to locate the organism in animal tissue to prevent epidemics from spreading through herds.
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