Abstract
Effects of factors affecting birth weight and weaning weight of 3-4 Brahman x ;,4 Angus and 3-4 Angus x 14 Brahman embryo transfer calves were analyzed. Data used in this project were collected at the Angleton Research Station. Backcross matings from combinations using Brahman and Angus inheritance was used to create 32 embryo transfer families. The mean birth weight for steer calves was 36.71 0.44 kg which was significantly (p < .0001) heavier than the heifer's birth weight of 33.55 ︢0.46 kg. No difference for birth weight existed between 1-4 Angus and 1-4 Brahman calves. A contrast compared 3-4 Angus calves out of purebred sires vs those out of purebred dams (AB or BA x A vs A x AB or BA), this comparison determined that the effect of having a purebred Angus dam vs the effect of having a purebred Angus sire resulted in a significantly (P = .005) heavier calf produced by the purebred Angus dams. Similar contrasts were conducted to detect any differences in 3-4 Brahman calves. The effect of purebred Brahman sire and a crossbred dam vs a cossbred sire and a purebred Brahman dam was significant (P = .0001) indicating that 3-4 Brahman calves out of crossbred dams were heavier at birth than those out of purebred Brahman dams. The mean weaning weight for all 241 calves was 231.67 ︢2.19 kg. Three-quarter Angus calves were 18.04 + 4.32kg heavier than @4 Brahman calves (P = .0001). The effect of a purebred Brahman sire and a crossbred dam vs a crossbred sire and a purebred dam was significant (p = .05). Paternal half-sibs had a birth weight heritability estimate of .27 ︢.16. Maternal half-sibs exhibited a birth weight heritability estimate of .44 ︢.20. The birth weight heritability estimate for full-sib families was .41 ︢.12. Paternal half-sibs had a weaning weight heritability estimate of .24 ︢.18. While maternal halfsibs had a weaning weight heritability estimate of .34 .20 the weaning weight heritability estimate for full-sib families was .27 ︢.12.
Cook, Billy Jack (1995). Preweaning growth characteristics for Brahman-Angus embryo transfer calves. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1995 -THESIS -C66.