The influence of growth hormone on growth in young cattle

Abstract

Summary Twelve pairs of identical‐twin heifer calves were divided into 3 groups. For 12 consecutive weeks daily injections were carried out as follows: Group 1 Growth hormone 5 mg/100 lb body weight Group 2 L‐thyroxine 0.5 mg/100 lb body weight Group 3 Normal saline 1 cm 3 During the injection period the growth‐hormone group gained in live weight by approximately 14 lb more than the control group, whereas the weight gain of the l‐thyroxine group was some 12 lb less than that of the control group. The extra gain in height made by the growth hormone and l‐thyroxine groups compared with that made by the control group amounted to 20 mm and 14 mm respectively. L‐thyroxine increased blood‐sugar levels by some 20–30%. The increase in blood sugar recorded in the growth‐hormone group was slightly less than this and was probably due to the contamination of the growth hormone with thyrotrophic hormone. Non‐protein nitrogen levels in the blood were unaffected by either growth hormone or l‐thyroxine.