Beef Cattle Performance and Progeny Tests for Gain, Efficiency, Carcass Conformation and Earliness of Maturity

Abstract

THE performance and progency test reported in this study were undertaken to evaluate various peformance criteria for selecting bulls, especially the selection of bulls on the basis of postweaning growth made on a low concentrate, high roughage ration. Materials and Methods From 1953 through 1960 all bulls in the U.C. inbred Hereford line were performance tested. No bull calves were castrated. All bulls of a calf crop were tested concurrently under similar conditions. To each of 12 cooperating cattleman a pair of concurrently tested bulls was loaned for breeding. Their steers calves, usually 10 per bull were aquired by the University at weaning time for testing at Davis, California. In choosing a pair of bulls for a cooperator an effort was made to have a large difference as possible between the members of a pair in their rates of gain while on a fattening ration. The desire to have the bulls of a pair as close to the same age as possible and the reluctance of cooperators to take a bull grading two minus or less on the University of California confirmation scale (Rollins and Wagon, 1956) restricted the size of the selection differential just describe. Copyright © . .