New Directions for Biosciences Research in Agriculture High-Reward Opportunities (1985) / Chapter Skim
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3. Animal Science
3. Animal Science
Pages 32-53
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From page 32... ...
The turkey industry has been particularly successful in using quantitative genetic principles to produce bigbreasted turkeys efficiently. Now the quality of these birds is controlled through the use of artificial insemination.
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From page 33... ...
This represents an estimated annual economic loss of $14 billion. Until recently the research approaches available to address disease losses in food animals have been limited.
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From page 34... ...
The payoff from intensified efforts in animal disease control will probably come much more quickly than results from research in either metabolic regulation or reproduction because of the solid foundations already being laid in this area for both man and animals. For example, studies at the ARS Plum Island Animal Disease Center in New York, on the molecular biology of foot and mouth disease, in addition to dissecting the physical chemistry and biochemists of the virus, have led to trials of a promising vaccine based on the cloned surface protein of the virus.
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From page 35... ...
A vaccine is simply an antigen or set of antigens unique to a disease-causing organism that stimulates a specific immune response against the disease agent. The interaction of the T cell receptor with antigen is unique in that recognition involves proteins of the MHC that also play an important role in helping to distinguish between foreign substances, which should be destroyed, and self proteins, which should not be destroyed.
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From page 36... ...
Another lymphokine, interferon, already has found clinical application in the treatment of some cancers and viral diseases in humans, and is undergoing field trials as a preventive measure for bovine respiratory disease. Opportunities now exist to characterize lymphokines fully, isolate the genes that code for them, and clone these genes to obtain sufficient quantities of various lymphocyte hormones for the study of their immune response regulation properties.
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From page 37... ...
Intensified investigation of antibodies and the T cell receptor in food animals would particularly apply to ongoing studies of a number of important livestock viral diseases such as bluetongue, malignant catarrhal fever, bovine leukemia, scrapie, pseudorabies, African swine fever, Marek's disease, and avian influenza and leukosis; bacterial diseases such as diarrhea of the newborn and mastitis; rickettsial diseases such as anaplasmosis; and parasitic diseases such as babesiosis. The greatest problem in combating these diseases is providing early diagnosis so that treatment can be given before economic loss occurs.
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From page 38... ...
The development of subunit vaccines, which contain only the critical part of the pathogen necessary to stimulate antibody production and not its genetic material, will solve many of the problems presented by conventional vaccines. Using monoclonal antibodies, scientists at the ARS Plum Island Animal Disease Center and others have identified and cloned the gene that codes for a major foot and mouth disease viral surface protein.
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From page 39... ...
Diseases can often be controlled, however, if the vector can be altered or eliminated. Cloning of specific genes of vectors -- gnats, ticks, black flies and mosquitoes -- can substantially increase understanding of the transmissibility of a disease agent and aid in its eradication or control.
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From page 40... ...
Characterization of recognition properties between vectors and the disease agents they transmit will provide clues to control surest The increasing knowledge about genes that regulate the immune response has already led to the identification of lymphokines and other immune response enhancers. In addition to these areas the further exploitation of monoclonal antibodies and recombinantDNA technology will improve current methods used to identify and control infectious agents.
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From page 41... ...
Synthetic peptides corresponding to part of one viral surface protein of foot and mouth disease have been shown to protect animals against live foot and mouth disease virus of that type. Subunit vaccines would provide greater effectiveness with less risk than conventional vaccines and have the potential to be produced economically.
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From page 42... ...
Excellent examples of this approach are the basic research program in parasitology at the Beltsville Agricultural Research Center in Maryland and the exotic animal disease research program at the Plum Island center in New York, where genetic engineering methods are being exploited to develop a safe vaccine for one type of foot and mouth disease. The ARS will benefit by focusing research on a number of specific diseases and by concentrating on the full utilization of existing Facilities and the acquisition of new equipment.
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From page 43... ...
Endogenous chemical mediators as well as their effects on the metabolism and function of different cell types must be identified and characterized. Research focused on understanding the influences of endogenous chemical mediators and on the consumption, digestion, and utilization of nutrients will lead to increased metabolic efficiency in food animals.
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From page 44... ...
Preliminary results show that injections of bovine growth hormone can cause up to a 40 percent increase in milk production in dairy cows and a marked increase in growth rate in beef animals. Research in the area of endogenous chemical mediators has tremendous potential for direct applications that will result in significant increases in the efficiency of animal production.
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From page 45... ...
Monoclonal antibodies, affinity chromatography, and nuclear magnetic resonance, which makes use of the absorption of electromagnetic waves to identify receptor structures and characterize biochemical events, provide an unprecedented opportunity to probe the biological processes in cell metabolism. Monoclonal antibodies, for example, because of their elegant specificity, can be used to block specific transport systems, enzymes, and regulatory proteins.
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From page 46... ...
There can be no doubt that these efforts will lead to tremendous increases in the efficiency of food production in food animals. Research Status The efficiency of food production by animals is closely related to the regulation of metabolism during pregnancy, growth, lactation, and egg production.
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From page 47... ...
More specifically the ARS should: · Identify, isolate, and characterize specific endogenous chemical mediators involved in organ-organ and cell-cell communication; · Develop fundamental knowledge of intracellular regulation of metabolism and functional interrelationships between organelles and other cellular components; · Delineate the response mechanisms involved in the translation of extracellular signals into intracellular biochemical events; o Identify interrelationships between feedstuffs, microbial fermentation, and nutrient availability in the digestive tract; · Characterize mechanisms and factors associated with the efficiency of nutrient absorption from the digestive tract; and · Using this new knowledge, develop means to manipulate these key control systems in specific tissues such as muscle, adipose, and bone, and thereby increase the efficiency of animal production. Currently only a very few small laboratory groups are studying endogenous chemical regulators and cellular metabolism.
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From page 48... ...
Information gained in attempts to answer these questions should be useful for turning genes on and off in both cell lines and adult tissue. Just as medical researchers have switched on the gene for fetal hemoglobin production in humans with sickle cell disease to compensate for the production of defective hemoglobin by the adult gene, so too might the gene for double muscling in cattle be transferred and switched on in market animals.
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From page 49... ...
In the dairy industry, however, production of bull calves by embryo transfer may provide an efficient means of amplifying the genes of the best cows through their sons. Additional applications of this technology include the intercontinental transport of germ plasm via embryos economically and with less risk of spreading disease than with transport of animals or semen.
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From page 50... ...
Addition of Genetic Information to Embryos The ability to obtain embryos by in vitro fertilization or to remove them from the female reproductive tract temporarily for various procedures is useful in a variety of genetic manipulations. For example, it is possible to inject genes into the pronuclei of a one-cell embryo so that the genes are duplicated automatically each time the cells divide.
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From page 51... ...
Less than 70 percent of adult female farm animals produce live young in any given breeding season. Barriers to reproductive efficiency include production of nonviable gametes, fertilization failure, embryonic mortality, and losses at birth and in the first few weeks of extrauterine life.
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From page 52... ...
It is entirely appropriate that agricultural research be expanded in this area, especially since species differences in reproductive processes necessitate the study of food animals themselves. Research Status The new biology methods can greatly enhance the understanding of reproduction and the study and modification of differentiation, important not only to the agricultural sciences but to all areas of biology.
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From page 53... ...
This service might be analogous to tissue culture cell banks established and maintained for the biomedical research community, including the registry of cell lines at the American Type Culture Collection, Rockville, Maryland; the Human Genetic Mutant Cell Repository maintained by the Institute for Medical Research, Camden, New Jersey; and the National Cancer Institute's Frozen Tumor Bank maintained at the Frederick Cancer Research Facility in Frederick, Maryland. There are several substantial laboratory groups in institutions studying animal differentiation, in vitro manipulation, addition of genetic information to gametes and embryos, and reproductive efficiency.
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