Evaluation of Sire × Dam Breed Interactions for Preweaning Beef Cattle Traits in the Southern Region

Birth and weaning weight data collected at experiment stations in the southern region were utilized to assess importance of sire × dam breed interactions. Five data sets were partitioned taking into consideration individual sire, sire breed, dam breed, and location as follows: data set 1 (birth weight = 407 observations, weaning weight = 407) involved Brahman (33) bulls mated to Brahman and Angus cows at two locations; data set 2 (birth weight = 972, weaning weight = 972) involved Brahman (24) bulls mated to Brahman and Hereford cows at two locations; data set 3 (birth weight = 488, weaning weight = 552) involved Angus (19) bulls mated to Angus and Hereford cows at two locations; data set 4 (birth weight = 1037, weaning weight = 1088) involved Hereford (34) bulls mated to Angus and Hereford cows at three locations; data set 5 (birth weight = 1198, weaning weight = 1198) involved Hereford (44) bulls mated to Hereford and Brahman × Hereford cows at four locations. Each data set was analyzed assuming a mathematical model that included effects for location, year/location, sire/year/location, dam breed, location × dam breed, dam breed × year/location, sire/year/location × dam breed, age of dam, and sex of calf. Weaning age was included as a covariate for weaning weight. For birth weight, the sire/year/location × dam breed interaction was significant only for data sets 3 (P < .05) and 4 (P < .01). For weaning weight, the sire/year/location × dam breed interaction was significant for data sets 2 (P < .05), 3 (P < .01), and 4 (P < .01). In general, these results indicate that significance of the sire/year/location × dam breed interaction for birth weight and weaning weight was inconsistent for the various data sets.