Endometrial gene expression of lactating Holstein cows: Impact of pre-estrus progesterone and intensity of estrous expression

This study aimed to evaluate if different concentrations of progesterone (P4) before estrus and different intensities of estrous expression affected endometrial gene expression in lactating Holstein cows. Animals were randomly assigned into 2 experimental groups: control P4 and low P4. Cows underwent a presynchronization protocol involving a GnRH injection and P4 implant, followed by a PGF2α injection and implant removal after 7 d, and a second GnRH injection 48 h later. The P4 treatment began 3 d after the second GnRH injection, with low P4 cows receiving 3 PGF2α injections (12 h apart), and control P4 cows receiving no PGF2α injections.