Amen, Tonya Sue (2004-12). Birth, weaning, carcass, and meat traits in Bos indicus-Bos taurus reciprocal backcross calves produced through embryo transfer. Master's Thesis.
Angus - Bos indicus (Brahman or Nellore) reciprocal backcross embryo transfer
calves belonging to 28 full-sib families were evaluated for differences in birth weight
(BW), gestation length (GL), weaning weight (WW), carcass weight (HCW),
longissimus muscle area (REA), fat thickness (adjusted (ADJFAT) and
actual(ACTFAT)), intramuscular fat (MARB), and Warner-Bratzler shear force
Family types with a greater proportion of Bos indicus in the sire in relation to the
amount in the dam (F1 x A and B x F1) averaged longer GL and heavier BW than their
respective reciprocal crosses (A x F1 and F1 x B). Calves had longer GL when the F1
parent was BA as opposed to AB. Small differences (statistically insignificant) were
detected for BW, but no consistent difference was found between offspring of AB and
BA parental types, with the exception of male F1-sired calves.
F1 x A and B x F1 crosses also showed a large BW difference between males and
females (about 5.0 kg), while A x F1 and F1 x B crosses showed no BW difference
between males and females. Further examination within each sex showed a difference
between male reciprocals that was two times that of females.
Calves with a higher percentage of Bos indicus in the sire compared to the
proportion in the dam showed the same trend, as they were still heavier at weaning, and
produced heavier carcasses than the reciprocal crosses, though these differences were
As a whole, A backcross calves had more ACTFAT, more ADJFAT, larger REA,
more MARB, and lower WBSF than B backcross calves, though no significant
differences were detected between reciprocal crosses for any of these traits.
These results suggest that for weight related traits, especially BW, both the breed
constitution of the calf and the cross that produces the calf play an important role in its
ultimate performance for Bos indicus crossbred calves. For carcass and meat related
traits, it appears that the breed make-up of the calf itself is more significant in
influencing performance than the cross used to produce the calf.