Direct and correlated responses to selection
for improved feed conversion were estimated
from performance records of 1459 Polled
Hereford cattle born from the spring of 1967
through the spring of 1979. Data were analyzed
using a multiple-trait, derivative-free, restricted
maximum likelihood (MTDFREML) procedure.
A full animal model was used to calculate genetic
and phenotypic (co)variances. The withinherd
breeding values that resulted from the
solution of the mixed model equations were
regressed on year to create selection response
curves. Feed conversion was shown to respond
favorably to direct selection, with feed/gain
changing -.005 per year.
