Episodic release of LH during gestation in the cow

Abstract
Blood samples were collected at 10-min intervals for 10 h via a jugular vein cannula from cows early (52-56 days) and late (256-261 days) in gestation. All of the 5 early pregnant cows but only 3/5 late pregnant cows exhibited LH [luteinizing hormone] peaks. There was also a reduction (P = 0.04) in pulse frequency and the amplitude of peaks (P < 0.02) in the late pregnant cows.