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The incidence of dwarfism is Increasing in registered and commercial beef herds throughout the United States. The dwarfism is conditioned by an autosomal recessive gene with complete penetrance. Breeders definitely, though unconsciously, favor the heterozygote in the selection of sires. The dwarf gene in the heterozygous state has such a marked effect upon the frontal bones that heterozygous and homozygous normals can be differentiated, with a high degree of accuracy, from the relationships of the diagnostic points on the head profile. Several different means have been developed for distinguishing the dwarfcarrier and dwarf-free genotypes in mature bulls. Tests in the field under varying conditions indicate that it is feasible to use this method of diagnosis for differentiating between dwarf-carrier and dwarf-free bulls for breeders and commercial cattlemen. The organization of such a program and the problems to be overcome are herein discussed. This is a report of some of the research work on the California phase of a regional cooperative study in the Western States on Project W-1, “Improvement of Beef Cattle Through the Application of Breeding Methods,” which is partially supported by the Research and Marketing Act of 1946 funds, and is carried on in cooperation with the staff for Beef Cattle Research of the Bureau of Animal Industry, United States Department of Agriculture stotioned at Denver. The New Mexico and Arizona Experiment Station herds provided critical data. The Western Region comprises the following states and territories: Alaska Agricultural Experiment StationNevada Agricultural Experiment StationArizona Agricultural Experiment StationNew Mexico Agricultural Experiment StationCalifornia Agricultural Experiment StationOregon Agricultural Experiment StationColorado Agricultural Experiment StationUtah Agricultural Experiment StationHawaii Agricultural Experiment StationWashington Agricultural Experiment StationIdaho Agricultural Experiment StationWyoming Agricultural Experiment StationMontana Agricultural Experiment Station |
