Detection of urinary luteinizing hormone in Japanese black cows after administration of gonadotropin-releasing hormone

The blood luteinizing hormone (LH) surge in cows is well studied. However, little is known about urinary LH in cows. This study examined urinary LH concentrations after administration of gonadotropin-releasing hormone (GnRH) in six Japanese black cows to induce LH secretion from the pituitary gland into the bloodstream. Abrupt rises in plasma and urinary LH were observed after GnRH administration. Plasma and urinary LH peaked at 2 and 5 hr, respectively. A positive correlation was observed between plasma LH concentrations and urinary LH amounts. Ovulation was confirmed in the cows after 48 hr of GnRH administration. These data strongly suggest that urinary LH is derived from plasma LH, which triggers ovulation in cows.

Automated summary

This study investigated the changes in urinary LH concentrations in six Japanese black cows after administration of GnRH. The results showed abrupt rises in both plasma and urinary LH levels after GnRH administration, with peak levels reached at 2 and 5 hours respectively. Additionally, a positive correlation was observed between plasma LH concentrations and urinary LH amounts, and ovulation in the cows was confirmed 48 hours post-GnRH administration.