tmpar <- par( mar = c(3.1,3.1,0,0), pty = "s" )
on.exit( par( tmpar ) )

attach( feed )
mplot( fi, bwg, group = trt, xaxt = "n", xlab = "", ylab = "" )
axis( 1, seq( 2400, 2700, by = 100 ) )
axis( 1, 2800, lab = F )
mlines( fi, predict( feed.reg ), group = trt, lty = c(3,4,1,2) )
tmp <- mean( fi )
# vertical line at fi mean
abline( v = tmp, lty = 4 )
# least squares means at same
points( rep( tmp, 4 ), predict( feed.reg, data.frame(
   la = la[!duplicated(trt)], cla = cla[!duplicated(trt)],
   fi = rep( tmp, 4 ) ) ), pch = 18 )
points( tapply( fi, trt, mean ), tapply( bwg, trt, mean ), pch = 0 )
detach( )
#mtext( "(b) marginal and LS means", 1, 3 )
mtext( "feed intake", 1, 2 )
mtext( "weight gain", 2, 2 )
#legend( 2550, 1325, c(".25 CLA",".5 CLA","Control",".5 LA"), lty = c(2,4,1,4),
#   pch = "1234" )
se.bar( 2700, 1350, std.dev( feed.ancova ), cap = "SD" )