General and Specific Combining Abilities of Inbred Lines of Hereford Cattle

Abstract

Data collected at the San Juan Basin Experiment Station, Hesperus, from 1946 through 1969 on inbred and linecross progeny representing eight lines were used. Weaning weight records on 1,069 heifer and 1,038 bull progeny and postweaning performance on 718 bulls were analyzed. Information on general combining ability, specific combining ability, inbred line differences and heterosis is presented. Traits studied include adjusted weaning weight of both sexes, initial test weight, final test weight, feed consumption, feed efficiency (unadjusted and adjusted for mid-weight) and daily gain of bulls. General combining ability as estimated by line of sire within the linecross population was important for all traits and was especially important for weaning weight of heifers and postweaning traits of bulls. General combining ability for maternal effects plus one-half the direct portion of general combining ability as measured by line of sire of dam was important only for weaning weight of bulls. Although less than a full complement of specific combining ability is included in these data, this effect as measured by the line of sire × line of sire of dam interaction was not important with the F values approximating unity except for postweaning daily gain of bulls.