This results in the steer twin being taller. This expanded growth rate at puberty is due to the increased production of the male sex hormone testosterone. Therefore, when the identical twin steer and bull are compared after puberty of the bull, the steer is taller but the bull is longer and heavier. This fact points out the inaccuracy of using height at the withers or hips as a measure of frame size. Further it dictates that in measuring frame size bulls must be compared with bulls and steers with steers.
Skeletons also grow proportionately.
The entire spinal column , which extends from the base of the skull through the tail, grows in concert. Therefore, the various segments are a constant percentage of the total length of the spinal column. A small framed animal has a shorter spinal column than a larger framed one but the neck or any other segment of the backbone is a constant percentage of total length. It is very common in the cattle industry to hear people refer to differences in length of neck, back or rump as a method of evaluation. The implication is that a certain animal is superior because it has a greater or lessor percentage of its length in a certain segment or area.