Effect of mid-luteal administration of non-steroidal aromatase inhibitor, letrozole on serum progesterone concentrations in crossbred cows exhibiting prolonged oestrus

Abstract

Letrozole is a non-steroidal aromatase inhibitor which inactivates the aromatase enzyme, preventing oestrogen production. A luteotropic effect is also attributed to this drug. The study conducted to assess the effect of letrozole administration on serum progesterone profile in prolonged oestrous crossbred cows revealed that intravenous administration of 250 µg letrozole at mid luteal phase had no significant effect on subsequent serum progesterone concentration in the ensuing oestrus or mid luteal phase among prolonged oestrous cows.