Short-term variations in plasma LH and testosterone in bull calves from birth to 1 year of age.

LH and testosterone levels in bull calves were studied in the plasma samples collected sequentially at 15-min intervals every month during the first year of life. An episodic pattern of LH release occurred after birth and the frequency and magnitude of the LH peaks increased up to 4 months of age and decreased thereafter. A testicular response was not observed before this age. It is suggested that this episodic LH activity is responsible for the testicular development which then initiates puberty.