tmpar <- par( mfcol=c(1,2), mar=c(3.1,2.1,0.1,.1) )
on.exit( { par( tmpar ); rm( tmpar, tmp ) } )

tmp <- effect.plot( forage.fit, stratum="cow", xlab="", ylab="", yaxt="n" )
axis( 2, .2 * -3:3 )
axis( 2, .1 * -7:7, F )
mtext( names( tmp )[4], 1, 1, at=4 )
mtext( "(a) cow effects", 1, 2 )

tmp <- effect.plot( forage.fit, stratum="Within", xlab="", ylab="", yaxt="n",
   xlim = c(.8,5.2) )
axis( 2, .2 * c(-1,0,1) )
axis( 2, .1 * c(-3,-1,1,3), F )
mtext( names( tmp )[c(3,5)], 1, 1, at=c(3,5) )
mtext( "(b) period effects", 1, 2 )