Genetic History of the Line 1 Hereford Cattle

Abstract

The United States Range Livestock Experiment Station, Miles City, Montana, in cooperation with the Montana Agricultural Experiment Station, undertook in 1936 to produce an inbred line of Hereford cattle basing selection on economic performance. The foundation sires of Line 1 were purchased from a Colorado breeder and the cows were Station cows that trace directly to five sires previously used in the herd. The original breeding program called for half- brother-sister matings as far as possible, but this plan could not be strictly adhered to. Inbreeding has increased rather slowly, and the inbreeding of the 1948 calves has reached only 15.95 percent. The inbreeding could have been higher had it not been for the losses of specific sires and selection pressure. The coefficient of relationship to Advance Domino 20th was found to be 44 percent and to Advance Domino 54th, 27 percent. Selection pressure for high weaning weights was ascribed as being responsible for the higher relationship to Advance Domino 20th. Record of performance results indicate that the line has increased in rate of gain and weight for age without much apparent loss of quality of carcass. LIB Domino 2d was one of the best bulls used in the line as measured by the performance of both his bull and steer offspring. Estimates of heritability were generally higher within Line | than they were in the entire population studied in a previous report. The relationships between the performance of the sire and the performance of the steer offspring from each sire are shown. The results obtained are discussed herein as a method for the improvement of beef cattle. The progress of Line 1 during the past 12 years should encourage other purebred breeders of beef cattle to develop lines in which selection is based on economic performance.