Biotechnology has yielded new and improved medicines for animals that help lower production costs and improve animal well being by fighting diseases caused by bacteria and parasites. For example, scientists have identified a new anti-bacterial compound that may serve as a substitute for using some antibiotics in animals, a practice that has been criticized for contributing to the increased prevalence of drug-resistant bacteria in human infections.
New or enhanced animal vaccines have also been developed through modern biotechnology techniques. Vaccines are now used to prevent diseases including: foot and mouth disease, scours, brucellosis, shipping fever, feline leukemia, rabies, and infections affecting cultivated fish.
Biotechnology has led to the development of rapid test kits to diagnose the health of livestock and companion animals. Some kits are commercially available, but they will have to be low cost and easy to use if they are to be widely accepted.
New or enhanced animal vaccines have also been developed through modern biotechnology techniques. Vaccines are now used to prevent diseases including: foot and mouth disease, scours, brucellosis, shipping fever, feline leukemia, rabies, and infections affecting cultivated fish.
Biotechnology has led to the development of rapid test kits to diagnose the health of livestock and companion animals. Some kits are commercially available, but they will have to be low cost and easy to use if they are to be widely accepted.
Making aTransgenic Animal
One way to produce transgenic animals is through a technique called microinjection. Once scientists have identified and isolated the piece of DNA comprising the gene to be transferred, it is injected into a fertilized egg of the desired animal using a very small glass needle visualized under a microscope. In approximately one percent of the injected eggs, the gene becomes a new "word" in the egg's "instruction manual" by physically combining with the egg's genome. Ideally, the new gene integrates into the genome before the egg begins to divide. If this occurs, every cell in the animal can contain the new protein and the animal will pass the gene on to its offspring. After injection of the gene, the fertilized egg is implanted into a surrogate mother where it fully develops into a transgenic animal.
Traits Being Introduced Into Animals
Currently, the only routine commercial use of transgenic animals (primarily mice) is in the area of human disease research. One way to characterize the range of genetic modifications that are being considered for use in animals is in the three broad areas of input, output, and value-added traits. Examples of each are described below.
Inputs Traits
An "input" trait helps livestock and dairy producers by increasing production efficiency.
Input traits that are being investigated for use in animals:
Faster, more efficient growth rates
Increased production of milk or wool Resistance to diseases caused by viruses and bacteria
Input traits that are being investigated for use in animals:
Faster, more efficient growth rates
Increased production of milk or wool Resistance to diseases caused by viruses and bacteria
Output Traits
An output trait helps consumers or downstream processors by enhancing the quality of the animal product.
Output traits that may prove to be beneficial:
Leaner, more tender beef and pork
Milk that lacks allergenic proteins, or results in increased amounts of cheese and yogurt
Output traits that may prove to be beneficial:
Leaner, more tender beef and pork
Milk that lacks allergenic proteins, or results in increased amounts of cheese and yogurt
Value-Added Traits
By adding or modifying genes, animals can function in completely new ways.
Producing large amounts of therapeutic proteins in animal milk may be an efficient, relatively low cost method to manufacture many proteins used to treat human diseases or proteins that have industrial value.
Transplanting animal organs into humans, or xenotransplantation, can be made more successful by genetically modifying the organs so that they are not as readily rejected by the human immune system. Development of animals that serve as models for human diseases to help scientists better understand prevention and treatment strategies.
Producing large amounts of therapeutic proteins in animal milk may be an efficient, relatively low cost method to manufacture many proteins used to treat human diseases or proteins that have industrial value.
Transplanting animal organs into humans, or xenotransplantation, can be made more successful by genetically modifying the organs so that they are not as readily rejected by the human immune system. Development of animals that serve as models for human diseases to help scientists better understand prevention and treatment strategies.
Biotechnology and Cloning of Animals
Advances in biotechnology have allowed scientists to make genetically identical copies or clones of animals. Duplication of an organism's genome occurs naturally when identical twins are born or when a plant is grown from a cutting of another plant. However, the world really took notice of cloning in 1997 when a group of Scottish researchers announced the birth of Dolly the sheep, which had been cloned using a single cell from an adult sheep. Dolly had only one "parent;" her nuclear genome was exactly like her "mother's" instead of being a combination of two parents. Therefore, Dolly could generally be thought of as her mother's identical twin.
To produce Dolly, scientists took an egg from a sheep and removed its nucleus (which contains the genome or instruction manual), rendering it unable to function or develop. Next, they took a cell with an intact genome from a different adult sheep (Dolly's "mother") and fused it to the sheep egg which lacked a genome. The egg, with its new genome, was stimulated to begin developing into an embryo and was implanted into a surrogate sheep where it grew normally,
resulting in the birth of Dolly. Dolly later gave birth to normal lambs.
To produce Dolly, scientists took an egg from a sheep and removed its nucleus (which contains the genome or instruction manual), rendering it unable to function or develop. Next, they took a cell with an intact genome from a different adult sheep (Dolly's "mother") and fused it to the sheep egg which lacked a genome. The egg, with its new genome, was stimulated to begin developing into an embryo and was implanted into a surrogate sheep where it grew normally,
resulting in the birth of Dolly. Dolly later gave birth to normal lambs. Benefits and Risks of Cloning
Researchers have cloned other mammals including cows, goats, pigs, and mice. However, the overall low rate of successful cloning and frequent occurrence of developmental abnormalities in cloned animals demonstrate the need for further research before cloning will be practical.
It has also been reported that cloned animals may exhibit health problems throughout their life. Cloned animals may age prematurely as Dolly was diagnosed with arthritis at a seemingly young age and cloned mice had a shorter than normal life span. Additionally, it was demonstrated that cloned mice were both larger in size and heavier than a control group of non-cloned mice.
If advances in animal cloning technology were to overcome the current obstacles, the most obvious benefit would be the ability of a farmer to have a herd of superior performing animals in one generation. Breeding companies could sell cloned embryos in a manner similar to the way in which semen is currently marketed. A potential drawback of this practice would be the loss of genetic diversity in livestock herds, but this could be avoided by limiting the number of cloned embryos of a given animal that were sold.
It has also been proposed that cloning could be used to increase the population of animals in an endangered species. The mouflon sheep, which is a wild Mediterranean sheep with less than 1000 animals remaining, was successfully cloned. Additionally, scientists are attempting to clone an endangered wild Asian ox, called the guar (the first cloned guar died of an intestinal illness shortly after birth) and possibly the giant Panda. Although possible, a recovering population of cloned animals would be hindered by a lack of genetic diversity and would not address the larger issue of how the animal became endangered.
It has also been reported that cloned animals may exhibit health problems throughout their life. Cloned animals may age prematurely as Dolly was diagnosed with arthritis at a seemingly young age and cloned mice had a shorter than normal life span. Additionally, it was demonstrated that cloned mice were both larger in size and heavier than a control group of non-cloned mice.
If advances in animal cloning technology were to overcome the current obstacles, the most obvious benefit would be the ability of a farmer to have a herd of superior performing animals in one generation. Breeding companies could sell cloned embryos in a manner similar to the way in which semen is currently marketed. A potential drawback of this practice would be the loss of genetic diversity in livestock herds, but this could be avoided by limiting the number of cloned embryos of a given animal that were sold.
It has also been proposed that cloning could be used to increase the population of animals in an endangered species. The mouflon sheep, which is a wild Mediterranean sheep with less than 1000 animals remaining, was successfully cloned. Additionally, scientists are attempting to clone an endangered wild Asian ox, called the guar (the first cloned guar died of an intestinal illness shortly after birth) and possibly the giant Panda. Although possible, a recovering population of cloned animals would be hindered by a lack of genetic diversity and would not address the larger issue of how the animal became endangered.
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