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Submitted to: Beltsville Agricultural Research Center Symposium
Publication Type: Government Publication Publication Acceptance Date: 2/1/1996 Publication Date: N/A Citation: N/A Interpretive Summary: An important goal for animal breeders is to feed people whether accomplished with biotechnology or with simpler methods. Biotechnology gives animal breeders the tools to trace individual genes across generations. If affordable, use of genetic markers to identify and to select the best genes could be used by all animal breeders to speed improvement of their populations. Until now, most of the important genes affecting profitability could not be traced, and animal breeders estimated only the total value of all genes. To estimate values of individual genes, breeders compare family members that inherited different genetic markers. If families are small, genetic value may be estimated poorly regardless of how many markers are tested. Small or moderate genetic differences can still be profitable if reproductive rates are high. Genetic markers may not be profitable for most females and for embryos given current reproductive rates. Success of marker-assisted selection depends greatly on the presence of a few genes with moderate or large effect. Industry cooperation will be needed to collect, to interpret, and to report genotypic data, especially if family members are widely dispersed and if different laboratories use different markers. Genetic markers are a sensible investment when working towards feeding the world's populations, considering the large improvements in animal performance that result from current genetic selection. Technical Abstract: In theory, all animal breeders could apply genetic marker technology and marker-assisted selection to speed improvement of their populations. In reality, the income from each new biotechnology must exceed its cost before it becomes useful. Fairly small advantages from genotyping will be profitable if reproductive rates are high. Genotyping of most females and of embryos will not be profitable given current reproductive rates. Success of marker-assisted selection depends greatly on the presence of a few genes with moderate or large effect. To estimate allele differences, breeders will genotype siblings in each elite family that have phenotype or progeny-test data. If allele differences are large at a particular locus, breeders will also genotype younger family members without data to speed the selection process. Progeny designs offer faster selection than grandprogeny designs because only one generation separates the tested ancestor from the selected descendants. If families are small, quantitative gene parameters are estimated poorly regardless of how many markers are tested. Estimated effects should be regressed for expected error content before use in breeding values. Industry cooperation will be needed to collect, to interpret, and to report genotypic data, especially if family members are widely dispersed and if different laboratories use different markers. Genetic markers are a sensible investment, especially considering the large improvements in animal performance that result from current genetic selection. |
