Twenty-four Hereford × Angus × Shorthorn steers, which were 18 months old, were divided at random into four groups of six. There were four treatments, two involving the feeding of supplementary protein and two involving implantation of the steers with hexoestrol, thus:

(1) basic ration, no hexoestrol;

(2) supplementary protein, no hexoestrol;

(3) basic ration, hexoestrol implant;

(4) supplementary protein, hexoestrol implant.

While the hexoestrol implantation produced a significantly higher growth rate, the addition of protein, above the level in the basic ration, had no effect.