Performance records of 1459 Polled Hereford
cattle were analyzed to estimate heritabilities
and genetic correlations of beef cattle traits
from birth to maturity. Estimates of heritability
(h2) for birth weight (BWT), weaning weight
(WWT), yearling weight (YWT), scrotal circumference
(SC), yearling height (YHT), mature
height (MHT), and mature weight (MWT) were
moderate to high, with the exception of WWT
(h2 = .14), and ranged from .38 to .72. The
traits associated with feed conversion, daily feed
intake (INT), average daily gain (ADG), and
feed conversion (CONV) had heritabilities of
.24, .25, and .14, respectively. Genetic correlations
(rg) between the growth traits (BWT,
WWT, YWT, YHT, MHT, MWT, and SC)
were positive and ranged from .20 to .88. The
rg=.99 between milk production (MILK) and
maternal weaning weight (MWW) indicates that
the traits are essentially the same and supports
the method in which many breed associations
calculate and report expected progeny differences
(EPDs) for milk production. The rg = .42
between ADG and INT, rg = .27 between INT
and CONV, and the rg = -.82 between ADG
and CONV suggest that faster gaining cattle
have greater feed intakes and are more efficient.
