Infertilidad asociada con la duración de la fase luteal en vacas postparto

After first postpartum ovulation most cows have a short luteal phase due to a premature secretion of PGF₂α from the uterus. Pregnancy rate in estrous cycles with short luteal phases is essentially nil. The lack of exposure of the uterus to P₄ and estrogen prior to first postpartum ovulation decreases the concentration of P₄ receptors and up regulates oxytocin receptors. The inadequate number of P₄ receptors and presence of endometrial oxytocin receptors earlier in cows with short than normal luteal phases allows premature release of PGF₂α and the resultant regression of the CL. During luteolysis, uterine and luteal PGF₂α cause death of the embryos mainly during the transition from morula to blastocyst when the embryos are more susceptible to embryotoxic effect.