| dc.description.abstract | Reproductive and weight traits were analyzed for Angus (A), Brahman (B),
Hereford (H), and Nellore (N) straightbred cows; F1 NA cows; 3/8N 5/8A cows and
quarter blood composite cows (BANH) of the four straightbreds in Central Texas.
Heterosis was estimated for calf crop born (CCB), calf crop weaned (CCW), and calf
survival (CS) by linear contrasts within cow breed groups. F1 NA cows expressed
heterosis (P < 0.0001) for CCB (0.22) and CCW (0.20). Except for the 3/8N 5/8Ac
cows, which resulted from the mating of NA bulls to 3/4A 1/4N cows, all of the
crossbred cow breed types expressed significant heterosis (P < 0.05) when compared to
the weighted average of the parental purebreds for CCB. BANHc cows that were the
result of mating NA bulls to HB cows expressed heterosis for CCB (0.35) (P < 0.001)
and CCW (0.29) (P < 0.05). The 3/8N 5/8Aa females produced by mating 3/4N 1/4A
bulls to NA cows expressed heterosis (P < 0.0001) for CCW (0.20). Heterosis for calf
survival was near zero for all breed types, but only two breed types of 3/8N 5/8A cows
were significantly greater than the weighted average of the parental purebreds. Heterosis
for birth weight (BWT) and weaning weight (WWT) was also analyzed by linear contrasts within cow breed groups. The BANHb and BANHc cows produced from
mating NA bulls to BH and HB F1 cows, respectively, expressed heterosis for BWT
(2.89 + 0.79 (P < 0.001) and 3.38 + 1.51 (P < 0.05)). All cow breed types expressed
significant heterosis (P < 0.05) for WWT. The BANH2 cows resulting from the mating
of NA bulls to F2 HB or BH cows expressed heterosis (P < 0.0001) for WWT (52.01 kg
+ 9.88). | en |
