WEIGHTED AVERAGES OF SIRE PROGENY TESTS FOR GROWTH TRAITS IN RECORD OF PERFORMANCE BEEF HERDS
Growth records of 281 744 calves born from 1971 to 1978 were used to calculate annual phenotypic and genetic trends for weaning weight and yearling weight. Genetic trends were computed as the weighted average of sire-transmitting abilities obtained from the Record of Performance National Beef Sire Monitoring Program. There were no significant differences between the genetic trends of all calves vs. calves which made a yearling weight for either weaning weight or yearling weight. Annual trends were positive for Angus, Hereford, and Shorthorn breeds, and were negative for Charolais, Limousin, Maine-Anjou and Simmental breeds. The interpretation of annual trends was complicated by the declining enrollment of herds on the test program which could have artificially altered the averages.